Programs & Examples On #Upn

The UPN (User Principal Name) is an Internet-style login name for the user based on the Internet standard RFC 822.

Angular 2 Cannot find control with unspecified name attribute on formArrays

For me, I was trying to add [formGroupName]="i" and/or formControlName and forgetting to specify the parent formArrayName. Pay attention to your form group tree.

Angular2 : Can't bind to 'formGroup' since it isn't a known property of 'form'

Don't use userForm = new FormGroup()

Use form = new FormGroup() instead.

And in the form use <form [formGroup]="form"> ...</form>. It works for me with angular 6

Disable Input fields in reactive form

If you want to disable first(formcontrol) then you can use below statement.


If strings starts with in PowerShell

$Group is an object, but you will actually need to check if $Group.samaccountname.StartsWith("string").

Change $Group.StartsWith("S_G_") to $Group.samaccountname.StartsWith("S_G_").

Powershell: A positional parameter cannot be found that accepts argument "xxx"

In my case there was a corrupted character in one of the named params ("-StorageAccountName" for cmdlet "Get-AzureStorageKey") which showed as perfectly normal in my editor (SublimeText) but Windows Powershell couldn't parse it.

To get to the bottom of it, I moved the offending lines from the error message into another .ps1 file, ran that, and the error now showed a botched character at the beginning of my "-StorageAccountName" parameter.

Deleting the character (again which looks normal in the actual editor) and re-typing it fixes this issue.

Laravel: getting a a single value from a MySQL query

On laravel 5.6 it has a very simple solution:

User::where('username', $username)->first()->groupName;

It will return groupName as a string.

Saving binary data as file using JavaScript from a browser

To do this task download.js library can be used. Here is an example from library docs:

download("data:image/gif;base64,R0lGODlhRgAVAIcAAOfn5+/v7/f39////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////yH5BAAAAP8ALAAAAABGABUAAAj/AAEIHAgggMGDCAkSRMgwgEKBDRM+LBjRoEKDAjJq1GhxIMaNGzt6DAAypMORJTmeLKhxgMuXKiGSzPgSZsaVMwXUdBmTYsudKjHuBCoAIc2hMBnqRMqz6MGjTJ0KZcrz5EyqA276xJrVKlSkWqdGLQpxKVWyW8+iJcl1LVu1XttafTs2Lla3ZqNavAo37dm9X4eGFQtWKt+6T+8aDkxUqWKjeQUvfvw0MtHJcCtTJiwZsmLMiD9uplvY82jLNW9qzsy58WrWpDu/Lp0YNmPXrVMvRm3T6GneSX3bBt5VeOjDemfLFv1XOW7kncvKdZi7t/S7e2M3LkscLcvH3LF7HwSuVeZtjuPPe2d+GefPrD1RpnS6MGdJkebn4/+oMSAAOw==", "dlDataUrlBin.gif", "image/gif");

Multiple radio button groups in MVC 4 Razor

I fixed a similar issue building a RadioButtonFor with pairs of text/value from a SelectList. I used a ViewBag to send the SelectList to the View, but you can use data from model too. My web application is a Blog and I have to build a RadioButton with some types of articles when he is writing a new post.

The code below was simplyfied.

List<SelectListItem> items = new List<SelectListItem>();

Dictionary<string, string> dictionary = new Dictionary<string, string>();

dictionary.Add("Texto", "1");
dictionary.Add("Foto", "2");
dictionary.Add("Vídeo", "3");

foreach (KeyValuePair<string, string> pair in objBLL.GetTiposPost())
    items.Add(new SelectListItem() { Text = pair.Key, Value = pair.Value, Selected = false });

ViewBag.TiposPost = new SelectList(items, "Value", "Text");

In the View, I used a foreach to build a radiobutton.

<div class="form-group">
    <div class="col-sm-10">
        @foreach (var item in (SelectList)ViewBag.TiposPost)
            @Html.RadioButtonFor(model => model.IDTipoPost, item.Value, false)
            <label class="control-label">@item.Text</label>


Notice that I used RadioButtonFor in order to catch the option value selected by user, in the Controler, after submit the form. I also had to put the item.Text outside the RadioButtonFor in order to show the text options.

Hope it's useful!

VBA macro that search for file in multiple subfolders

This sub will populate a Collection with all files matching the filename or pattern you pass in.

Sub GetFiles(StartFolder As String, Pattern As String, _
             DoSubfolders As Boolean, ByRef colFiles As Collection)

    Dim f As String, sf As String, subF As New Collection, s
    If Right(StartFolder, 1) <> "\" Then StartFolder = StartFolder & "\"
    f = Dir(StartFolder & Pattern)
    Do While Len(f) > 0
        colFiles.Add StartFolder & f
        f = Dir()
    If DoSubfolders then
        sf = Dir(StartFolder, vbDirectory)
        Do While Len(sf) > 0
            If sf <> "." And sf <> ".." Then
                If (GetAttr(StartFolder & sf) And vbDirectory) <> 0 Then
                        subF.Add StartFolder & sf
                End If
            End If
            sf = Dir()
        For Each s In subF
            GetFiles CStr(s), Pattern, True, colFiles
        Next s
    End If

End Sub


Dim colFiles As New Collection

GetFiles "C:\Users\Marek\Desktop\Makro\", FName & ".xls", True, colFiles
If colFiles.Count > 0 Then
    'work with found files
End If

SQL Server : export query as a .txt file

This is quite simple to do and the answer is available in other queries. For those of you who are viewing this:

select entries from my_entries where id='42' INTO OUTFILE 'bishwas.txt';

How to align linearlayout to vertical center?

For me, I have fixed the problem using android:layout_centerVertical="true" in a parent RelativeLayout:

<RelativeLayout ... >



How do I change Bootstrap 3 column order on mobile layout?

Starting with the mobile version first, you can achieve what you want, most of the time.

Examples here:,css,output

<div class="container">
      <h1>PUSH - PULL Bootstrap demo</h1>
    <h2>Version 1:</h2>

    <div class="row">

      <div class="col-xs-12 col-sm-5 col-sm-push-3 green">

      <div class="col-xs-12 col-sm-4 col-sm-push-3 gold">

      <div class="col-xs-12 col-sm-3 col-sm-pull-9 red">


    <h2>Version 2:</h2>

    <div class="row">

      <div class="col-xs-12 col-sm-4 col-sm-push-8 yellow">
        <hr> TOP ROW ON XS-SMALL

      <div class="col-xs-12 col-sm-4 col-sm-pull-4 blue">

      <div class="col-xs-12 col-sm-4 col-sm-pull-4 pink">


    <h2>Version 3:</h2>

    <div class="row">

      <div class="col-xs-12 col-sm-5 cyan">

      <div class="col-xs-12 col-sm-3 col-sm-push-4 orange">

      <div class="col-xs-12 col-sm-4 col-sm-pull-3 brown">


    <h2>Version 4:</h2>
    <div class="row">

      <div class="col-xs-12 col-sm-4 col-sm-push-8 darkblue">

      <div class="col-xs-12 col-sm-4 beige">

      <div class="col-xs-12 col-sm-4 col-sm-pull-8 silver">



Execution order of events when pressing PrimeFaces p:commandButton

It failed because you used ajax="false". This fires a full synchronous request which in turn causes a full page reload, causing the oncomplete to be never fired (note that all other ajax-related attributes like process, onstart, onsuccess, onerror and update are also never fired).

That it worked when you removed actionListener is also impossible. It should have failed the same way. Perhaps you also removed ajax="false" along it without actually understanding what you were doing. Removing ajax="false" should indeed achieve the desired requirement.

Also is it possible to execute actionlistener and oncomplete simultaneously?

No. The script can only be fired before or after the action listener. You can use onclick to fire the script at the moment of the click. You can use onstart to fire the script at the moment the ajax request is about to be sent. But they will never exactly simultaneously be fired. The sequence is as follows:

  • User clicks button in client
  • onclick JavaScript code is executed
  • JavaScript prepares ajax request based on process and current HTML DOM tree
  • onstart JavaScript code is executed
  • JavaScript sends ajax request from client to server
  • JSF retrieves ajax request
  • JSF processes the request lifecycle on JSF component tree based on process
  • actionListener JSF backing bean method is executed
  • action JSF backing bean method is executed
  • JSF prepares ajax response based on update and current JSF component tree
  • JSF sends ajax response from server to client
  • JavaScript retrieves ajax response
    • if HTTP response status is 200, onsuccess JavaScript code is executed
    • else if HTTP response status is 500, onerror JavaScript code is executed
  • JavaScript performs update based on ajax response and current HTML DOM tree
  • oncomplete JavaScript code is executed

Note that the update is performed after actionListener, so if you were using onclick or onstart to show the dialog, then it may still show old content instead of updated content, which is poor for user experience. You'd then better use oncomplete instead to show the dialog. Also note that you'd better use action instead of actionListener when you intend to execute a business action.

See also:

Call PHP function from Twig template

If you really know what you do and you don't mind the evil ways, this is the only additional Twig extension you'll ever need:

function evilEvalPhp($eval, $args = null)
    $result = null;
    return $result;

Where do I mark a lambda expression async?

To mark a lambda async, simply prepend async before its argument list:

// Add a command to delete the current Group
contextMenu.Commands.Add(new UICommand("Delete this Group", async (contextMenuCmd) =>
    SQLiteUtils slu = new SQLiteUtils();
    await slu.DeleteGroupAsync(groupName);

is there any PHP function for open page in new tab

This is a trick,

function OpenInNewTab(url) {

  var win =, '_blank');

In most cases, this should happen directly in the onclick handler for the link to prevent pop-up blockers, and the default "new window" behavior. You could do it this way, or by adding an event listener to your DOM object.

<div onclick="OpenInNewTab();">Something To Click On</div>

How to open maximized window with Javascript?'your_url', 'popup_name','height=' + screen.height + ',width=' + screen.width + ',resizable=yes,scrollbars=yes,toolbar=yes,menubar=yes,location=yes')

org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing

Instead of passing reference object passed the saved object, below is explanation which solve my issue:


Role savedEntity= entityManager.persist(role);

Entity framework left join

If you prefer method call notation, you can force a left join using SelectMany combined with DefaultIfEmpty. At least on Entity Framework 6 hitting SQL Server. For example:

using(var ctx = new MyDatabaseContext())
    var data = ctx
    .SelectMany(a => ctx.MyTable2
      .Where(b => b.Id2 == a.Id1)
      .Select(b => new
        Col2 = b == null ? (int?) null : b.Col2,

(Note that MyTable2.Col2 is a column of type int). The generated SQL will look like this:

    [Extent1].[Id1] AS [Id1], 
    [Extent1].[Col1] AS [Col1], 
    CASE WHEN ([Extent2].[Col2] IS NULL) THEN CAST(NULL AS int) ELSE  CAST( [Extent2].[Col2] AS int) END AS [Col2]
    FROM  [dbo].[MyTable1] AS [Extent1]
    LEFT OUTER JOIN [dbo].[MyTable2] AS [Extent2] ON [Extent2].[Id2] = [Extent1].[Id1]


Join on one-to-many relation in JPQL looks as follows:

select b.fname, b.lname from Users b JOIN b.groups c where c.groupName = :groupName 

When several properties are specified in select clause, result is returned as Object[]:

Object[] temp = (Object[]) em.createNamedQuery("...")
    .setParameter("groupName", groupName)
String fname = (String) temp[0];
String lname = (String) temp[1];

By the way, why your entities are named in plural form, it's confusing. If you want to have table names in plural, you may use @Table to specify the table name for the entity explicitly, so it doesn't interfere with reserved words:

@Entity @Table(name = "Users")     
public class User implements Serializable { ... } 

How to Load RSA Private Key From File

Two things. First, you must base64 decode the mykey.pem file yourself. Second, the openssl private key format is specified in PKCS#1 as the RSAPrivateKey ASN.1 structure. It is not compatible with java's PKCS8EncodedKeySpec, which is based on the SubjectPublicKeyInfo ASN.1 structure. If you are willing to use the bouncycastle library you can use a few classes in the bouncycastle provider and bouncycastle PKIX libraries to make quick work of this.


import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;

// ...   

String keyPath = "mykey.pem";
BufferedReader br = new BufferedReader(new FileReader(keyPath));
Security.addProvider(new BouncyCastleProvider());
PEMParser pp = new PEMParser(br);
PEMKeyPair pemKeyPair = (PEMKeyPair) pp.readObject();
KeyPair kp = new JcaPEMKeyConverter().getKeyPair(pemKeyPair);
samlResponse.sign(Signature.getInstance("SHA1withRSA").toString(), kp.getPrivate(), certs);

Dynamic WHERE clause in LINQ

alt text

You need something like this? Use the Linq Dynamic Query Library (download includes examples).

Check out ScottGu's blog for more examples.

The located assembly's manifest definition does not match the assembly reference

Is possible you have a wrong nugget versions in assemblyBinding try:

  1. Remove all assembly binding content in web.config / app.config:
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <assemblyIdentity name="Microsoft.Extensions.Logging.Abstractions" publicKeyToken="adb9793829ddae60" culture="neutral" />
    <bindingRedirect oldVersion="" newVersion="" />
    <assemblyIdentity name="Microsoft.Extensions.DependencyInjection" publicKeyToken="adb9793829ddae60" culture="neutral" />
    <bindingRedirect oldVersion="" newVersion="" />
    <assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="" newVersion="" />
  1. Type in Package Manager Console: Add-BindingRedirect
  2. All necessary binding redirects are generated
  3. Run your application and see if it works properly. If not, add any missing binding redirects that the package console missed.

Pandas convert dataframe to array of tuples

A generic way:

[tuple(x) for x in data_set.to_records(index=False)]

Java: JSON -> Protobuf & back conversion

Here is my utility class, you may use:

package <removed>;
 * Author @espresso stackoverflow.
 * Sample use:
 *      Model.Person reqObj = ProtoUtil.toProto(reqJson, Model.Person.getDefaultInstance());
        Model.Person res = personSvc.update(reqObj);
        final String resJson = ProtoUtil.toJson(res);
public class ProtoUtil {
    public static <T extends Message> String toJson(T obj){
            return JsonFormat.printer().print(obj);
        }catch(Exception e){
            throw new RuntimeException("Error converting Proto to json", e);
   public static <T extends MessageOrBuilder> T toProto(String protoJsonStr, T message){
            Message.Builder builder = message.getDefaultInstanceForType().toBuilder();
            T out = (T);
            return out;
        }catch(Exception e){
            throw new RuntimeException(("Error converting Json to proto", e);

How to add hyperlink in JLabel?

I'd like to offer yet another solution. It's similar to the already proposed ones as it uses HTML-code in a JLabel, and registers a MouseListener on it, but it also displays a HandCursor when you move the mouse over the link, so the look&feel is just like what most users would expect. If browsing is not supported by the platform, no blue, underlined HTML-link is created that could mislead the user. Instead, the link is just presented as plain text. This could be combined with the SwingLink class proposed by @dimo414.

public class JLabelLink extends JFrame {

private static final String LABEL_TEXT = "For further information visit:";
private static final String A_VALID_LINK = "";
private static final String A_HREF = "<a href=\"";
private static final String HREF_CLOSED = "\">";
private static final String HREF_END = "</a>";
private static final String HTML = "<html>";
private static final String HTML_END = "</html>";

public JLabelLink() {
    setTitle("HTML link via a JLabel");

    Container contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout(FlowLayout.LEFT));

    JLabel label = new JLabel(LABEL_TEXT);

    label = new JLabel(A_VALID_LINK);
    if (isBrowsingSupported()) {
        makeLinkable(label, new LinkMouseListener());


private static void makeLinkable(JLabel c, MouseListener ml) {
    assert ml != null;
    c.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));

private static boolean isBrowsingSupported() {
    if (!Desktop.isDesktopSupported()) {
        return false;
    boolean result = false;
    Desktop desktop = java.awt.Desktop.getDesktop();
    if (desktop.isSupported(Desktop.Action.BROWSE)) {
        result = true;
    return result;


private static class LinkMouseListener extends MouseAdapter {

    public void mouseClicked(java.awt.event.MouseEvent evt) {
        JLabel l = (JLabel) evt.getSource();
        try {
            URI uri = new;
            (new LinkRunner(uri)).execute();
        } catch (URISyntaxException use) {
            throw new AssertionError(use + ": " + l.getText()); //NOI18N

private static class LinkRunner extends SwingWorker<Void, Void> {

    private final URI uri;

    private LinkRunner(URI u) {
        if (u == null) {
            throw new NullPointerException();
        uri = u;

    protected Void doInBackground() throws Exception {
        Desktop desktop = java.awt.Desktop.getDesktop();
        return null;

    protected void done() {
        try {
        } catch (ExecutionException ee) {
            handleException(uri, ee);
        } catch (InterruptedException ie) {
            handleException(uri, ie);

    private static void handleException(URI u, Exception e) {
        JOptionPane.showMessageDialog(null, "Sorry, a problem occurred while trying to open this link in your system's standard browser.", "A problem occured", JOptionPane.ERROR_MESSAGE);

private static String getPlainLink(String s) {
    return s.substring(s.indexOf(A_HREF) + A_HREF.length(), s.indexOf(HREF_CLOSED));

//This method requires that s is a plain string that requires
//no further escaping
private static String linkIfy(String s) {
    return A_HREF.concat(s).concat(HREF_CLOSED).concat(s).concat(HREF_END);

//This method requires that s is a plain string that requires
//no further escaping
private static String htmlIfy(String s) {
    return HTML.concat(s).concat(HTML_END);

 * @param args the command line arguments
public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {

        public void run() {
            new JLabelLink().setVisible(true);

How to call Base Class's __init__ method from the child class?

If you are using Python 3, it is recommended to simply call super() without any argument:

class Car(object):
    condition = "new"

    def __init__(self, model, color, mpg):
        self.model = model
        self.color = color
        self.mpg   = mpg

class ElectricCar(Car):
    def __init__(self, battery_type, model, color, mpg):
        super().__init__(model, color, mpg)

car = ElectricCar('battery', 'ford', 'golden', 10)
print car.__dict__

Do not call super with class as it may lead to infinite recursion exceptions as per this answer.

npm install errors with Error: ENOENT, chmod

I have a similar problem specifucally : ERR! enoent ENOENT: no such file or directory, chmod 'node_modules/npm/node_modules/request/node_modules/http-signature/node_modules/sshpk/bin/sshpk-conv I tried all above solutions but no luck. I was using vagrant box, and the project was in a shared folder. The problems seems to be only there, when I move the project to another not shared folder (woth host), voila! problem solved. Just in case another person was using also vagrant

Shortcut key for commenting out lines of Python code in Spyder

On macOS:

Cmd + 1

On Windows, probably

Ctrl + (/) near right shift key

How to hide/show div tags using JavaScript?

Use the following code:

function hide {
document.getElementById('div').style.display = "none";
function show {
document.getElementById('div').style.display = "block";

combining two data frames of different lengths

I think I have come up with a quite shorter solution.. Hope it helps someone.<-function(df1, df2){

  #Collect all unique rownames
  total.rownames<-union(x = rownames(x = df1),y = rownames(x=df2))

  #Create a new dataframe with rownames
  df<-data.frame(row.names = total.rownames)

  #Get absent rownames for both of the dataframe
  absent.names.1<-setdiff(x = rownames(df1),y = rownames(df))
  absent.names.2<-setdiff(x = rownames(df2),y = rownames(df))

  #Fill absents with NAs
  df1.fixed<-data.frame(row.names = absent.names.1,matrix(data = NA,nrow = length(absent.names.1),ncol=ncol(df1)))

  df2.fixed<-data.frame(row.names = absent.names.2,matrix(data = NA,nrow = length(absent.names.2),ncol=ncol(df2)))

  #Finally cbind into new dataframe


In Python, how to display current time in readable format

All you need is in the documentation.

import time
time.strftime('%X %x %Z')
'16:08:12 05/08/03 AEST'

In Bash, how to add "Are you sure [Y/n]" to any command or alias?

Here is my solution that using localised regex. So in german also "j" for "Ja" would be interpreted as yes.

First argument is the question, if the second argument is "y" than yes would be the default answer otherwise no would be the default answer. The return value is 0 if the answer was "yes" and 1 if the answer was "no".

function shure(){
    if [ $# -gt 1 ] && [[ "$2" =~ ^[yY]*$ ]] ; then
        reg=$(locale noexpr)
        default=(0 1)
        reg=$(locale yesexpr)
        default=(1 0)
    read -p "$1 ${arg}? : " answer
    [[ "$answer" =~ $reg ]] && return ${default[1]} || return ${default[0]}

Here is a basic usage

# basic example default is no
shure "question message" && echo "answer yes" || echo "answer no"
# print "question message [y/N]? : "

# basic example default set to yes
shure "question message" y && echo "answer yes" || echo "answer no"
# print "question message [Y/n]? : "

AngularJS - Any way for $ to send request parameters instead of JSON?

I think the params config parameter won't work here since it adds the string to the url instead of the body but to add to what Infeligo suggested here is an example of the global override of a default transform (using jQuery param as an example to convert the data to param string).

Set up global transformRequest function:

var app = angular.module('myApp');

app.config(function ($httpProvider) {
    $httpProvider.defaults.transformRequest = function(data){
        if (data === undefined) {
            return data;
        return $.param(data);

That way all calls to $ will automatically transform the body to the same param format used by the jQuery $.post call.

Note you may also want to set the Content-Type header per call or globally like this:

$['Content-Type'] = 'application/x-www-form-urlencoded; charset=UTF-8';

Sample non-global transformRequest per call:

    var transform = function(data){
        return $.param(data);

    $"/foo/bar", requestData, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},
        transformRequest: transform
    }).success(function(responseData) {
        //do stuff with response

Serialize an object to string


Public Function XmlSerializeObject(ByVal obj As Object) As String

    Dim xmlStr As String = String.Empty

    Dim settings As New XmlWriterSettings()
    settings.Indent = False
    settings.OmitXmlDeclaration = True
    settings.NewLineChars = String.Empty
    settings.NewLineHandling = NewLineHandling.None

    Using stringWriter As New StringWriter()
        Using xmlWriter__1 As XmlWriter = XmlWriter.Create(stringWriter, settings)

            Dim serializer As New XmlSerializer(obj.[GetType]())
            serializer.Serialize(xmlWriter__1, obj)

            xmlStr = stringWriter.ToString()
        End Using

    End Using

    Return xmlStr.ToString
End Function

Public Function XmlDeserializeObject(ByVal data As [String], ByVal objType As Type) As Object

    Dim xmlSer As New System.Xml.Serialization.XmlSerializer(objType)
    Dim reader As TextReader = New StringReader(data)

    Dim obj As New Object
    obj = DirectCast(xmlSer.Deserialize(reader), Object)
    Return obj
End Function


public string XmlSerializeObject(object obj)
    string xmlStr = String.Empty;
    XmlWriterSettings settings = new XmlWriterSettings();
    settings.Indent = false;
    settings.OmitXmlDeclaration = true;
    settings.NewLineChars = String.Empty;
    settings.NewLineHandling = NewLineHandling.None;

    using (StringWriter stringWriter = new StringWriter())
        using (XmlWriter xmlWriter = XmlWriter.Create(stringWriter, settings))
            XmlSerializer serializer = new XmlSerializer( obj.GetType());
            serializer.Serialize(xmlWriter, obj);
            xmlStr = stringWriter.ToString();
    return xmlStr.ToString(); 

public object XmlDeserializeObject(string data, Type objType)
    XmlSerializer xmlSer = new XmlSerializer(objType);
    StringReader reader = new StringReader(data);

    object obj = new object();
    obj = (object)(xmlSer.Deserialize(reader));
    return obj;

add new element in laravel collection object

If you want to add a product into the array you can use:

$item['product'] = $product;

BeanFactory vs ApplicationContext

To add onto what Miguel Ping answered, here is another section from the documentation that answers this as well:

Short version: use an ApplicationContext unless you have a really good reason for not doing so. For those of you that are looking for slightly more depth as to the 'but why' of the above recommendation, keep reading.

(posting this for any future Spring novices who might read this question)

What's the proper value for a checked attribute of an HTML checkbox?

I think this may help:

First read all the specs from Microsoft and
You'd see that the setting the actual element of a checkbox needs to be done on the ELEMENT PROPERTY, not the UI or attribute.

Secondly, you need to be aware that the checked attribute RETURNS a string "true", "false"
Why is this important? Because you need to use the correct Type. A string, not a boolean. This also important when parsing your checkbox.
$('mycheckbox')[0].checked = "true"

if($('mycheckbox')[0].checked === "true"){ //do something }

You also need to realize that the "checked" ATTRIBUTE is for setting the value of the checkbox initially. This doesn't do much once the element is rendered to the DOM. Picture this working when the webpage loads and is initially parsed.
I'll go with IE's preference on this one: <input type="checkbox" checked="checked"/>

Lastly, the main aspect of confusion for a checkbox is that the checkbox UI element is not the same as the element's property value. They do not correlate directly. If you work in .net, you'll discover that the user "checking" a checkbox never reflects the actual bool value passed to the controller. To set the UI, I use both $('mycheckbox').val(true); and $('mycheckbox').attr('checked', 'checked');

In short, for a checked checkbox you need:
Initial DOM: <input type="checkbox" checked="checked">
Element Property: $('mycheckbox')[0].checked = "true";
UI: $('mycheckbox').val(true); and $('mycheckbox').attr('checked', 'checked');

Rotating x axis labels in R for barplot

Andre Silva's answer works great for me, with one caveat in the "barplot" line:

barplot(mtcars$qsec, col="grey50", 
    ylab="mtcars - qsec", ylim=c(0,5+max(mtcars$qsec)),
    xlab = "",
    xaxt = "n", 

Notice the "xaxt" argument. Without it, the labels are drawn twice, the first time without the 60 degree rotation.

ViewPager and fragments — what's the right way to store fragment's state?

I found another relatively easy solution for your question.

As you can see from the FragmentPagerAdapter source code, the fragments managed by FragmentPagerAdapter store in the FragmentManager under the tag generated using:

String tag="android:switcher:" + viewId + ":" + index;

The viewId is the container.getId(), the container is your ViewPager instance. The index is the position of the fragment. Hence you can save the object id to the outState:

protected void onSaveInstanceState(Bundle outState) {
    outState.putInt("viewpagerid" , mViewPager.getId() );

    protected void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState != null)
        viewpagerid=savedInstanceState.getInt("viewpagerid", -1 );  

    MyFragmentPagerAdapter titleAdapter = new MyFragmentPagerAdapter (getSupportFragmentManager() , this);        
    mViewPager = (ViewPager) findViewById(;
    if (viewpagerid != -1 ){

If you want to communicate with this fragment, you can get if from FragmentManager, such as:

getSupportFragmentManager().findFragmentByTag("android:switcher:" + viewpagerid + ":0")

What is the difference between a "function" and a "procedure"?

This is a well-known old question, but I'd like to share some more insights about modern programming language research and design.

Basic answer

Traditionally (in the sense of structured programming) and informally, a procedure is a reusable structural construct to have "input" and to do something programmable. When something is needed to be done within a procedure, you can provide (actual) arguments to the procedure in a procedure call coded in the source code (usually in a kind of an expression), and the actions coded in the procedures body (provided in the definition of the procedure) will be executed with the substitution of the arguments into the (formal) parameters used in the body.

A function is more than a procedure because return values can also be specified as the "output" in the body. Function calls are more or less same to procedure calls, except that you can also use the result of the function call, syntactically (usually as a subexpression of some other expression).

Traditionally, procedure calls (rather than function calls) are used to indicate that no output must be interested, and there must be side effects to avoid the call being no-ops, hence emphasizing the imperative programming paradigm. Many traditional programming languages like Pascal provide both "procedures" and "functions" to distinguish this intentional difference of styles.

(To be clear, the "input" and "output" mentioned above are simplified notions based on the syntactic properties of functions. Many languages additionally support passing arguments to parameters by reference/sharing, to allow users transporting information encoded in arguments during the calls. Such parameter may even be just called as "in/out parameter". This feature is based on the nature of the objects being passed in the calls, which is orthogonal to the properties of the feature of procedure/function.)

However, if the result of a function call is not needed, it can be just (at least logically) ignored, and function definitions/function calls should be consistent to procedure definitions/procedure calls in this way. ALGOL-like languages like C, C++ and Java, all provide the feature of "function" in this fashion: by encoding the result type void as a special case of functions looking like traditional procedures, there is no need to provide the feature of "procedures" separately. This prevents some bloat in the language design.

Since SICP is mentioned, it is also worth noting that in the Scheme language specified by RnRS, a procedure may or may not have to return the result of the computation. This is the union of the traditional "function" (returning the result) and "procedure" (returning nothing), essentially same to the "function" concept of many ALGOL-like languages (and actually sharing even more guarantees like applicative evaluations of the operands before the call). However, old-fashion differences still occur even in normative documents like SRFI-96.

I don't know much about the exact reasons behind the divergence, but as I have experienced, it seems that language designers will be happier without specification bloat nowadays. That is, "procedure" as a standalone feature is unnecessary. Techniques like void type is already sufficient to mark the use where side effects should be emphasized. This is also more natural to users having experiences on C-like languages, which are popular more than a few decades. Moreover, it avoids the embarrassment in cases like RnRS where "procedures" are actually "functions" in the broader sense.

In theory, a function can be specified with a specified unit type as the type of the function call result to indicate that result is special. This distinguishes the traditional procedures (where the result of a call is uninterested) from others. There are different styles in the design of a language:

  • As in RnRS, just marking the uninterested results as "unspecified" value (of unspecified type, if the language has to mention it) and it is sufficient to be ignored.
  • Specifying the uninterested result as the value of a dedicated unit type (e.g. Kernel's #inert) also works.
  • When that type is a further a bottom type, it can be (hopefully) statically verified and prevented used as a type of expression. The void type in ALGOL-like languages is exactly an example of this technique. ISO C11's _Noreturn is a similar but more subtle one in this kind.

Further reading

As the traditional concept derived from math, there are tons of black magic most people do not bother to know. Strictly speaking, you won't be likely get the whole things clear as per your math books. CS books might not provide much help, either.

With concerning of programming languages, there are several caveats:

  • Functions in different branches of math are not always defined having same meanings. Functions in different programming paradigms may also be quite different (even sometimes the syntaxes of function call look similar). Sometimes the reasons to cause the differences are same, but sometimes they are not.
    • It is idiomatic to model computation by mathematical functions and then implement the underlying computation in programming languages. Be careful to avoid mapping them one to one unless you know what are being talked about.
  • Do not confuse the model with the entity be modeled.
    • The latter is only one of the implementation to the former. There can be more than one choices, depending on the contexts (the branches of math interested, for example).
    • In particular, it is more or less similarly absurd to treat "functions" as "mappings" or subsets of Cartesian products like to treat natural numbers as Von-Neumann encoding of ordinals (looking like a bunch of {{{}}, {}}...) besides some limited contexts.
  • Mathematically, functions can be partial or total. Different programming languages have different treatment here.
    • Some functional languages may honor totality of functions to guarantee the computation within the function calls always terminate in finite steps. However, this is essentially not Turing-complete, hence weaker computational expressiveness, and not much seen in general-purpose languages besides semantics of typechecking (which is expected to be total).
    • If the difference between the procedures and functions is significant, should there be "total procedures"? Hmm...
  • Constructs similar to functions in calculi used to model the general computation and the semantics of the programming languages (e.g. lambda abstractions in lambda calculi) can have different evaluation strategies on operands.
    • In traditional the reductions in pure calculi as well in as evaluations of expressions in pure functional languages, there are no side effects altering the results of the computations. As a result, operands are not required to be evaluated before the body of the functions-like constructs (because the invariant to define "same results" is kept by properties like ß-equivalence guaranteed by Church-Rosser property).
    • However, many programming languages may have side effects during the evaluations of expressions. That means, strict evaluation strategies like applicative evaluation are not the same to non-strict evaluation ones like call-by-need. This is significant, because without the distinction, there is no need to distinguish function-like (i.e. used with arguments) macros from (traditional) functions. But depending on the flavor of theories, this still can be an artifact. That said, in a broader sense, functional-like macros (esp. hygienic ones) are mathematical functions with some unnecessary limitations (syntactic phases). Without the limitations, it might be sane to treat (first-class) function-like macros as procedures...
    • For readers interested in this topic, consider some modern abstractions.
  • Procedures are usually considered out of the scope of traditional math. However, in calculi modeling the computation and programming language semantics, as well as contemporary programming language designs, there can be quite a big family of related concepts sharing the "callable" nature. Some of them are used to implement/extend/replace procedures/functions. There are even more subtle distinctions.

How can I tell where mongoDB is storing data? (its not in the default /data/db!)

I found mine here on a OSX system /usr/local/var/mongodb

Split pandas dataframe in two if it has more than 10 rows

def split_and_save_df(df, name, size, output_dir):
    Split a df and save each chunk in a different csv file.

        df : pandas df to be splitted
        name : name to give to the output file
        size : chunk size
        output_dir : directory where to write the divided df
    import os
    for i in range(0, df.shape[0],size):
        start  = i
        end    = min(i+size-1, df.shape[0]) 
        subset = df.loc[start:end] 
        output_path = os.path.join(output_dir,f"{name}_{start}_{end}.csv")
        print(f"Going to write into {output_path}")
        output_size = os.stat(output_path).st_size
        print(f"Wrote {output_size} bytes")

SQL Server - boolean literal?

You should consider that a "true value" is everything except 0 and not only 1. So instead of 1=1 you should write 1<>0.

Because when you will use parameter (@param <> 0) you could have some conversion issue.

The most know is Access which translate True value on control as -1 instead of 1.

How to swap String characters in Java?

public static String shuffle(String s) {
    List<String> letters = Arrays.asList(s.split(""));
    StringBuilder t = new StringBuilder(s.length());
    for (String k : letters) {
    return t.toString();

How to set .net Framework 4.5 version in IIS 7 application pool

There is no v4.5 shown in the gui, and typically you don't need to manually specify v4.5 since it's an in-place update. However, you can set it explicitly with appcmd like this:

appcmd set apppool / [App Pool Name] /managedRuntimeVersion:v4.5

Appcmd is located in %windir%\System32\inetsrv. This helped me to fix an issue with Web Deploy, where it was throwing an ERROR_APPPOOL_VERSION_MISMATCH error after upgrading from v4.0 to v4.5.

MS article on setting .Net version for App Pool

What is the "double tilde" (~~) operator in JavaScript?

It hides the intention of the code.

It's two single tilde operators, so it does a bitwise complement (bitwise not) twice. The operations take out each other, so the only remaining effect is the conversion that is done before the first operator is applied, i.e. converting the value to an integer number.

Some use it as a faster alternative to Math.floor, but the speed difference is not that dramatic, and in most cases it's just micro optimisation. Unless you have a piece of code that really needs to be optimised, you should use code that descibes what it does instead of code that uses a side effect of a non-operation.

Update 2011-08:

With optimisation of the JavaScript engine in browsers, the performance for operators and functions change. With current browsers, using ~~ instead of Math.floor is somewhat faster in some browsers, and not faster at all in some browsers. If you really need that extra bit of performance, you would need to write different optimised code for each browser.

See: tilde vs floor

Entity Framework VS LINQ to SQL VS ADO.NET with stored procedures?

Stored procedures:


  • Great flexibility
  • Full control over SQL
  • The highest performance available


  • Requires knowledge of SQL
  • Stored procedures are out of source control
  • Substantial amount of "repeating yourself" while specifying the same table and field names. The high chance of breaking the application after renaming a DB entity and missing some references to it somewhere.
  • Slow development



  • Rapid development
  • Data access code now under source control
  • You're isolated from changes in DB. If that happens you only need to update your model/mappings in one place.


  • Performance may be worse
  • No or little control over SQL the ORM produces (could be inefficient or worse buggy). Might need to intervene and replace it with custom stored procedures. That will render your code messy (some LINQ in code, some SQL in code and/or in the DB out of source control).
  • As any abstraction can produce "high-level" developers having no idea how it works under the hood

The general tradeoff is between having a great flexibility and losing lots of time vs. being restricted in what you can do but having it done very quickly.

There is no general answer to this question. It's a matter of holy wars. Also depends on a project at hand and your needs. Pick up what works best for you.

MySQL: Get column name or alias from query

This is the same as thefreeman but more in pythonic way using list and dictionary comprehension

columns = cursor.description 
result = [{columns[index][0]:column for index, column in enumerate(value)} for value in cursor.fetchall()]


HikariCP - connection is not available

I managed to fix it finally. The problem is not related to HikariCP. The problem persisted because of some complex methods in REST controllers executing multiple changes in DB through JPA repositories. For some reasons calls to these interfaces resulted in a growing number of "freezed" active connections, exhausting the pool. Either annotating these methods as @Transactional or enveloping all the logic in a single call to transactional service method seem to solve the problem.

How does `scp` differ from `rsync`?

it's better to think in a practical context. In our team, we use rsync -aP to replace a bad cassandra host in our cluster. We can't do this with scp (slow and no progress preservation).

"for line in..." results in UnicodeDecodeError: 'utf-8' codec can't decode byte

Your file doesn't actually contain UTF-8 encoded data; it contains some other encoding. Figure out what that encoding is and use it in the open call.

In Windows-1252 encoding, for example, the 0xe9 would be the character é.

'Microsoft.ACE.OLEDB.16.0' provider is not registered on the local machine. (System.Data)

For anyone that is still stuck on this issue after trying the above. If you are right-clicking on the database and going to tasks->import, then here is the issue. Go to your start menu and under sql server, find the x64 bit import export wizard and try that. Worked like a charm for me, but it took me FAR too long to find it Microsoft!

Angular2 material dialog has issues - Did you add it to @NgModule.entryComponents?

This is happening because this is a dynamic component and you didn't add it to entryComponents under @NgModule.

Simply add it there:

  /* ----------------- */
  entryComponents: [ DialogResultExampleDialog ] // <---- Add it here

Look at how the Angular team talks about entryComponents:

entryComponents?: Array<Type<any>|any[]>

Specifies a list of components that should be compiled when this module is defined. For each component listed here, Angular will create a ComponentFactory and store it in the ComponentFactoryResolver.

Also, this is the list of the methods on @NgModule including entryComponents...

As you can see, all of them are optional (look at the question marks), including entryComponents which accept an array of components:

  providers?: Provider[]
  declarations?: Array<Type<any>|any[]>
  imports?: Array<Type<any>|ModuleWithProviders|any[]>
  exports?: Array<Type<any>|any[]>
  entryComponents?: Array<Type<any>|any[]>
  bootstrap?: Array<Type<any>|any[]>
  schemas?: Array<SchemaMetadata|any[]>
  id?: string

how to add values to an array of objects dynamically in javascript?

You have to instantiate the object first. The simplest way is:

var lab =["1","2","3"];
var val = [42,55,51,22];
var data = [];
for(var i=0; i<4; i++)  {
    data.push({label: lab[i], value: val[i]});

Or an other, less concise way, but closer to your original code:

for(var i=0; i<4; i++)  {
   data[i] = {};              // creates a new object
   data[i].label = lab[i];
   data[i].value = val[i];    

array() will not create a new array (unless you defined that function). Either Array() or new Array() or just [].

I recommend to read the MDN JavaScript Guide.

Does my application "contain encryption"?

UPDATE: Using HTTPS is now exempt from the ERN as of late September, 2016

Unfortunately, I believe that your app "contains encryption" in terms of US BIS even if you just use HTTPS (if your app is not an exception included in question 2).

Quote from FAQ on iTunes Connect:

"How do I know if I can follow the Exporter Registration and Reporting (ERN) process?

If your app uses, accesses, implements or incorporates industry standard encryption algorithms for purposes other than those listed as exemptions under question 2, you need to submit for an ERN authorization. Examples of standard encryption are: AES, SSL, https. This authorization requires that you submit an annual report to two U.S. Government agencies with information about your app every January. "

"2nd Question: Does your product qualify for any exemptions provided under category 5 part 2?

There are several exemptions available in US export regulations under Category 5 Part 2 (Information Security & Encryption regulations) for applications and software that use, access, implement or incorporate encryption.

All liabilities associated with misinterpretation of the export regulations or claiming exemption inaccurately are borne by owners and developers of the apps.

You can answer “YES” to the question if you meet any of the following criteria:

(i) if you determine that your app is not classified under Category 5, Part 2 of the EAR based on the guidance provided by BIS at encryption question. The Statement of Understanding for medical equipment in Supplement No. 3 to Part 774 of the EAR can be accessed at Electronic Code of Federal Regulations site. Please visit the Question #15 in the FAQ section of the encryption page for sample items BIS has listed that can claim Note 4 exemptions.

(ii) your app uses, accesses, implements or incorporates encryption for authentication only

(iii) your app uses, accesses, implements or incorporates encryption with key lengths not exceeding 56 bits symmetric, 512 bits asymmetric and/or 112 bit elliptic curve

(iv) your app is a mass market product with key lengths not exceeding 64 bits symmetric, or if no symmetric algorithms, not exceeding 768 bits asymmetric and/or 128 bits elliptic curve.

Please review Note 3 in Category 5 Part 2 to understand the criteria for mass market definition.

(v) your app is specially designed and limited for banking use or ‘money transactions.’ The term ‘money transactions’ includes the collection and settlement of fares or credit functions.

(vi) the source code of your app is “publicly available”, your app distributed at free of cost to general public, and you have met the notification requirements provided under 740.13.(e).

Please visit encryption web page in case you need further help in determining if your app qualifies for any exemptions.

If you believe that your app qualifies for an exemption, please answer “YES” to the question."

What is the keyguard in Android?

Keyguard basically refers to the code that handles the unlocking of the phone. it's like the keypad lock on your nokia phone a few years back just with the utility on a touchscreen.

you can find more info it you look in android/app or com\android\internal\policy\impl

Good Luck !

applying css to specific li class

I believe it's because #ID styles trump .class styles when computing the final style of an element. Try changing your li from class to id, or you can try adding !important to your class, like this:

    color: #C1C1C1; !important

Is there a "between" function in C#?

Or if you want to bound the value to the interval:

public static T EnsureRange<T>(this T value, T min, T max) where T : IComparable<T>
        if (value.CompareTo(min) < 0)
            return min;
        else if (value.CompareTo(max) > 0)
            return max;
            return value;

It is like two-sided Math.Min/Max

Casting interfaces for deserialization in JSON.NET

For what it's worth, I ended up having to handle this myself for the most part. Each object has a Deserialize(string jsonStream) method. A few snippets of it:

JObject parsedJson = this.ParseJson(jsonStream);
object thingyObjectJson = (object)parsedJson["thing"];
this.Thing = new Thingy(Convert.ToString(thingyObjectJson));

In this case, new Thingy(string) is a constructor that will call the Deserialize(string jsonStream) method of the appropriate concrete type. This scheme will continue to go downward and downward until you get to the base points that json.NET can just handle.

this.Name = (string)parsedJson["name"];
this.CreatedTime = DateTime.Parse((string)parsedJson["created_time"]);

So on and so forth. This setup allowed me to give json.NET setups it can handle without having to refactor a large part of the library itself or using unwieldy try/parse models that would have bogged down our entire library due to the number of objects involved. It also means that I can effectively handle any json changes on a specific object, and I do not need to worry about everything that object touches. It's by no means the ideal solution, but it works quite well from our unit and integration testing.

Python vs Cpython

So what is CPython?

CPython is the original Python implementation. It is the implementation you download from People call it CPython to distinguish it from other, later, Python implementations, and to distinguish the implementation of the language engine from the Python programming language itself.

The latter part is where your confusion comes from; you need to keep Python-the-language separate from whatever runs the Python code.

CPython happens to be implemented in C. That is just an implementation detail, really. CPython compiles your Python code into bytecode (transparently) and interprets that bytecode in a evaluation loop.

CPython is also the first to implement new features; Python-the-language development uses CPython as the base; other implementations follow.

What about Jython, etc.?

Jython, IronPython and PyPy are the current "other" implementations of the Python programming language; these are implemented in Java, C# and RPython (a subset of Python), respectively. Jython compiles your Python code to Java bytecode, so your Python code can run on the JVM. IronPython lets you run Python on the Microsoft CLR. And PyPy, being implemented in (a subset of) Python, lets you run Python code faster than CPython, which rightly should blow your mind. :-)

Actually compiling to C

So CPython does not translate your Python code to C by itself. Instead, it runs an interpreter loop. There is a project that does translate Python-ish code to C, and that is called Cython. Cython adds a few extensions to the Python language, and lets you compile your code to C extensions, code that plugs into the CPython interpreter.

Git Diff with Beyond Compare

Windows 10, Git v2.13.2

My .gitconfig. Remember to add escape character for '\' and '"'.

    tool = bc4
    prompt = false
[difftool "bc4"]
    cmd = \"C:\\Program Files\\Beyond Compare 4\\BCompare.exe\" \"$LOCAL\" \"$REMOTE\"
    tool = bc4
[mergetool "bc4"]
    path = C:\\Program Files\\Beyond Compare 4\\BCompare.exe

You may reference setting up beyond compare as difftool for using git commands to config it.


<table border="1"></table>

should do the trick.

500 internal server error at GetResponse()

For me this error occurred because I had 2 web API actions that had the exact same signatures and both had the same verbs, HttpPost, what I did was change one of the verbs (the one used for updating) to PUT and the error was removed. The following in my catch statement helped in getting to the root of the problem:

catch (WebException webex)
                WebResponse errResp = webex.Response;
                using (Stream respStream = errResp.GetResponseStream())
                    StreamReader reader = new StreamReader(respStream);
                    string text = reader.ReadToEnd();

Easy way to concatenate two byte arrays

If you prefer ByteBuffer like @kalefranz, there is always the posibility to concatenate two byte[] (or even more) in one line, like this:

byte[] c = ByteBuffer.allocate(a.length+b.length).put(a).put(b).array();

Regular Expression with wildcards to match any character

The following should work:

ABC: *\([a-zA-Z]+\) *(.+)


ABC:            # match literal characters 'ABC:'
 *              # zero or more spaces
\([a-zA-Z]+\)   # one or more letters inside of parentheses
 *              # zero or more spaces
(.+)            # capture one or more of any character (except newlines)

To get your desired grouping based on the comments below, you can use the following:

(ABC:) *(\([a-zA-Z]+\).+)

Gradle, Android and the ANDROID_HOME SDK location

For Windows:

  1. Add ANDROID_HOME to the Environment Variables: ANDROID_HOME = C:/Users/YOUR_USERNAME/AppData/Local/Android/sdk
  2. Add %ANDROID_HOME%\platform-tools to the PATH.

How to add a response header on nginx when using proxy_pass?

There is a module called HttpHeadersMoreModule that gives you more control over headers. It does not come with Nginx and requires additional installation. With it, you can do something like this:

location ... {
  more_set_headers "Server: my_server";

That will "set the Server output header to the custom value for any status code and any content type". It will replace headers that are already set or add them if unset.

How to validate an email address in PHP

If you're just looking for an actual regex that allows for various dots, underscores and dashes, it as follows: [a-zA-z0-9.-]+\@[a-zA-z0-9.-]+.[a-zA-Z]+. That will allow a fairly stupid looking email like to be validated.

Getting an error "fopen': This function or variable may be unsafe." when compling

This is a warning for usual. You can either disable it by

#pragma warning(disable:4996)

or simply use fopen_s like Microsoft has intended.

But be sure to use the pragma before other headers.

Set Content-Type to application/json in jsp file

You can do via Page directive.

For example:

<%@ page language="java" contentType="application/json; charset=UTF-8"
  • contentType="mimeType [ ;charset=characterSet ]" | "text/html;charset=ISO-8859-1"

The MIME type and character encoding the JSP file uses for the response it sends to the client. You can use any MIME type or character set that are valid for the JSP container. The default MIME type is text/html, and the default character set is ISO-8859-1.

What is the difference between an annotated and unannotated tag?


The difference between the commands is that one provides you with a tag message while the other doesn't. An annotated tag has a message that can be displayed with git-show(1), while a tag without annotations is just a named pointer to a commit.

More About Lightweight Tags

According to the documentation: "To create a lightweight tag, don’t supply any of the -a, -s, or -m options, just provide a tag name". There are also some different options to write a message on annotated tags:

  • When you use git tag <tagname>, Git will create a tag at the current revision but will not prompt you for an annotation. It will be tagged without a message (this is a lightweight tag).
  • When you use git tag -a <tagname>, Git will prompt you for an annotation unless you have also used the -m flag to provide a message.
  • When you use git tag -a -m <msg> <tagname>, Git will tag the commit and annotate it with the provided message.
  • When you use git tag -m <msg> <tagname>, Git will behave as if you passed the -a flag for annotation and use the provided message.

Basically, it just amounts to whether you want the tag to have an annotation and some other information associated with it or not.

How to round the double value to 2 decimal points?

you can also use this code

public static double roundToDecimals(double d, int c)  
   int temp = (int)(d * Math.pow(10 , c));  
   return ((double)temp)/Math.pow(10 , c);  

It gives you control of how many numbers after the point are needed.

d = number to round;   
c = number of decimal places  

think it will be helpful

@AspectJ pointcut for all methods of a class with specific annotation

You could use Spring's PerformanceMonitoringInterceptor and programmatically register the advice using a beanpostprocessor.

@Target({ ElementType.TYPE, ElementType.METHOD })
public @interface Monitorable


public class PerformanceMonitorBeanPostProcessor extends ProxyConfig implements BeanPostProcessor, BeanClassLoaderAware, Ordered,

  private Class<? extends Annotation> annotationType = Monitorable.class;

  private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

  private Advisor advisor;

  public void setBeanClassLoader(ClassLoader classLoader)
    this.beanClassLoader = classLoader;

  public int getOrder()

  public void afterPropertiesSet()
    Pointcut pointcut = new AnnotationMatchingPointcut(this.annotationType, true);
    Advice advice = getInterceptor();
    this.advisor = new DefaultPointcutAdvisor(pointcut, advice);

  private Advice getInterceptor()
    return new PerformanceMonitoringInterceptor();

  public Object postProcessBeforeInitialization(Object bean, String beanName)
    return bean;

  public Object postProcessAfterInitialization(Object bean, String beanName)
    if(bean instanceof AopInfrastructureBean)
      return bean;
    Class<?> targetClass = AopUtils.getTargetClass(bean);
    if(AopUtils.canApply(this.advisor, targetClass))
      if(bean instanceof Advised)
        return bean;
        ProxyFactory proxyFactory = new ProxyFactory(bean);
        return proxyFactory.getProxy(this.beanClassLoader);
      return bean;

How to set column header text for specific column in Datagridview C#

Dg_View.Columns.Add("userid","User Id");
Dg_View.Columns[0].Width = 100;

Dg_View.Columns.Add("username", "User name");
Dg_View.Columns[0].Width = 100;

Error: No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlClient'

I had the same problem and the only thing that works for my was to uninstall entity framework package from each project using Uninstall-Package. And then intall it again in the whole solution. It will ask you to choose in which project you want to install it, you shall select all.

How to make a browser display a "save as dialog" so the user can save the content of a string to a file on his system?

In case anyone is still wondering...

I did it like this:

<a href="data:application/xml;charset=utf-8,your code here" download="filename.html">Save</a>

cant remember my source but it uses the following techniques\features:

  1. html5 download attribute
  2. data uri's

Found the reference:

EDIT: As you can gather from the comments this does NOT work in

  1. Internet Explorer (works in Edge v13 though)
  2. iOS Safari
  3. Opera Mini

How to truncate milliseconds off of a .NET DateTime

A way for easy reading is...

//Remove milliseconds
DateTime date = DateTime.Now;
date = DateTime.ParseExact(date.ToString("yyyy-MM-dd HH:mm:ss"), "yyyy-MM-dd HH:mm:ss", null);

And more...

//Remove seconds
DateTime date = DateTime.Now;
date = DateTime.ParseExact(date.ToString("yyyy-MM-dd HH:mm"), "yyyy-MM-dd HH:mm", null);

//Remove minutes
DateTime date = DateTime.Now;
date = DateTime.ParseExact(date.ToString("yyyy-MM-dd HH"), "yyyy-MM-dd HH", null);

//and go on...

What's the difference between a proxy server and a reverse proxy server?

A forward proxy serves users: it helps users access the server.

A reverse proxy serves the server: it protects the server from users.

T-SQL CASE Clause: How to specify WHEN NULL

The issue is that NULL is not considered to be equal to anything even not to itself, but the strange part is that is also not not equal to itself.

Consider the following statements (which is BTW illegal in SQL Server T-SQL but is valid in My-SQL, however this is what ANSI defines for null, and can be verified even in SQL Server by using case statements etc.)


SELECT NULL <> NULL -- Results in NULL

So there is no true/false answer to the question, instead the answer is also null.

This has many implications, for example in

  1. CASE statements, in which any null value will always use the ELSE clause unless you use explicitly the WHEN IS NULL condition (NOT the WHEN NULL condition )
  2. String concatenation, as
    SELECT a + NULL -- Results in NULL
  3. In a WHERE IN or WHERE NOT IN clause, as if you want correct results make sure in the correlated sub-query to filter out any null values.

One can override this behavior in SQL Server by specifying SET ANSI_NULLS OFF, however this is NOT recommended and should not be done as it can cause many issues, simply because deviation of the standard.

(As a side note, in My-SQL there is an option to use a special operator <=> for null comparison.)

In comparison, in general programming languages null is treated is a regular value and is equal to itself, however the is the NAN value which is also not equal to itself, but at least it returns 'false' when comparing it to itself, (and when checking for not equals different programming languages have different implementations).

Note however that in the Basic languages (i.e. VB etc.) there is no 'null' keyword and instead one uses the 'Nothing' keyword, which cannot be used in direct comparison and instead one needs to use 'IS' as in SQL, however it is in fact equal to itself (when using indirect comparisons).

HTML - Display image after selecting filename

This can be done using HTML5, but will only work in browsers that support it. Here's an example.

Bear in mind you'll need an alternative method for browsers that don't support this. I've had a lot of success with this plugin, which takes a lot of the work out of your hands.

Difference between jar and war in Java

War -

distribute Java-based web applications. A WAR has the same file structure as a JAR file, which is a single compressed file that contains multiple files bundled inside it.

Jar -

The .jar files contain libraries, resources and accessories files like property files.

WAR files are used to combine JSPs, servlets, Java class files, XML files, javascript libraries, JAR libraries, static web pages, and any other resources needed to run the application.

jquery .on() method with load event

As the other have mentioned, the load event does not bubble. Instead you can manually trigger a load-like event with a custom event:

$('#item').on('namespace/onload', handleOnload).trigger('namespace/onload')

If your element is already listening to a change event:

$('#item').on('change', handleChange).trigger('change')

I find this works well. Though, I stick to custom events to be more explicit and avoid side effects.

ImportError: No module named pip

Try to install pip through Python:

Please go to:

and download, and then run:

(sudo) python

Chrome Extension - Get DOM content

The terms "background page", "popup", "content script" are still confusing you; I strongly suggest a more in-depth look at the Google Chrome Extensions Documentation.

Regarding your question if content scripts or background pages are the way to go:

Content scripts: Definitely
Content scripts are the only component of an extension that has access to the web-page's DOM.

Background page / Popup: Maybe (probably max. 1 of the two)
You may need to have the content script pass the DOM content to either a background page or the popup for further processing.

Let me repeat that I strongly recommend a more careful study of the available documentation!
That said, here is a sample extension that retrieves the DOM content on StackOverflow pages and sends it to the background page, which in turn prints it in the console:


// Regex-pattern to check URLs against. 
// It matches URLs like: http[s]://[...][...]
var urlRegex = /^https?:\/\/(?:[^./?#]+\.)?stackoverflow\.com/;

// A function to use as callback
function doStuffWithDom(domContent) {
    console.log('I received the following DOM content:\n' + domContent);

// When the browser-action button is clicked...
chrome.browserAction.onClicked.addListener(function (tab) {
    // ...check the URL of the active tab against our pattern and...
    if (urlRegex.test(tab.url)) {
        // ...if it matches, send a message specifying a callback too
        chrome.tabs.sendMessage(, {text: 'report_back'}, doStuffWithDom);


// Listen for messages
chrome.runtime.onMessage.addListener(function (msg, sender, sendResponse) {
    // If the received message has the expected format...
    if (msg.text === 'report_back') {
        // Call the specified callback, passing
        // the web-page's DOM content as argument


  "manifest_version": 2,
  "name": "Test Extension",
  "version": "0.0",

  "background": {
    "persistent": false,
    "scripts": ["background.js"]
  "content_scripts": [{
    "matches": ["*://**"],
    "js": ["content.js"]
  "browser_action": {
    "default_title": "Test Extension"

  "permissions": ["activeTab"]

"ORA-01438: value larger than specified precision allowed for this column" when inserting 3

NUMBER (precision, scale) means precision number of total digits, of which scale digits are right of the decimal point.

NUMBER(2,2) in other words means a number with 2 digits, both of which are decimals. You may mean to use NUMBER(4,2) to get 4 digits, of which 2 are decimals. Currently you can just insert values with a zero integer part.

More info at the Oracle docs.

How to convert std::string to lower case?

If the string contains UTF-8 characters outside of the ASCII range, then boost::algorithm::to_lower will not convert those. Better use boost::locale::to_lower when UTF-8 is involved. See

Sending mass email using PHP

I would insert all the emails into a database (sort of like a queue), then process them one at a time as you have done in your code (if you want to use swiftmailer or phpmailer etc, you can do that too.)

After each mail is sent, update the database to record the date/time it was sent.

By putting them in the database first you have

  1. a record of who you sent it to
  2. if your script times out or fails and you have to run it again, then you won't end up sending the same email out to people twice
  3. you can run the send process from a cron job and do a batch at a time, so that your mail server is not overwhelmed, and keep track of what has been sent

Keep in mind, how to automate bounced emails or invalid emails so they can automatically removed from your list.

If you are sending that many emails you are bound to get a few bounces.

How do I check if file exists in jQuery or pure JavaScript?

This works for me:

function ImageExist(url) 
   var img = new Image();
   img.src = url;
   return img.height != 0;

Commenting out code blocks in Atom

Atom does not have block comment by default, so I would recommend searching for atom packages by "block comment" and install the one suits to you.

I prefer because is has the closest keyboard shortcut to line comment and it works as i need it to, meaning it would not comment the whole line but only the selected text.

line comment: CTRL+/ block comment: CTRL+SHIFT+/ (with the plugin installed)

What is the use of the JavaScript 'bind' method?

Another usage is that you can pass binded function as an argument to another function which is operating under another execution context.

var name = "sample";
function sample(){
var cb = sample.bind(this);

function somefunction(cb){
  //other code
}{}, cb);

Replace first occurrence of pattern in a string

There are a number of ways that you could do this, but the fastest might be to use IndexOf to find the index position of the letter you want to replace and then substring out the text before and after what you want to replace.

How to create Drawable from resource

If you are trying to get the drawable from the view where the image is set as,


then the drawable will return only null value with the following code...

   Drawable drawable = (Drawable) ivshowing.getDrawable();

So, it's better to set the image with the following code, if you wanna retrieve the drawable from a particular view.


only then the drawable will we converted exactly.

How to insert a file in MySQL database?

The other answers will give you a good idea how to accomplish what you have asked for....


There are not many cases where this is a good idea. It is usually better to store only the filename in the database and the file on the file system.

That way your database is much smaller, can be transported around easier and more importantly is quicker to backup / restore.

return query based on date

if you want to get items anywhere on that date you need to compare two dates

You can create two dates off of the first one like this, to get the start of the day, and the end of the day.

var startDate = new Date(); // this is the starting date that looks like ISODate("2014-10-03T04:00:00.188Z")


var dateMidnight = new Date(startDate);


var query = {
        inserted_at: {

//MORNING: Sun Oct 12 2014 00:00:00 GMT-0400 (EDT)
//MIDNIGHT: Sun Oct 12 2014 23:59:59 GMT-0400 (EDT)

How can I detect if this dictionary key exists in C#?

What is the type of c.PhysicalAddresses? If it's Dictionary<TKey,TValue>, then you can use the ContainsKey method.

Unable to get spring boot to automatically create database schema

to connect to mysql with springboot as well as creating table automatically into database: spring.datasource.url=jdbc:mysql://localhost:3306/solace spring.datasource.username=root spring.datasource.password=root spring.jpa.generate-ddl=true spring.jpa.hibernate.ddl-auto=update

Best PHP IDE for Mac? (Preferably free!)

PDT eclipse from ZEND has a mac version (PDT all-in-one).

I've been using it for about 3 months and it's pretty solid and has debugging capabilities with xdebug (debug howto) and zend debugger.

Remote origin already exists on 'git push' to a new repository

I had the same problem when I first set up using Bitbucket.

My problem was that I needed to change the word origin for something self-defined. I used the name of the application. So:

git remote add AppName https://[email protected]/somewhere/something.git

Deleting array elements in JavaScript - delete vs splice

Array.remove() Method

John Resig, creator of jQuery created a very handy Array.remove method that I always use it in my projects.

// Array Remove - By John Resig (MIT Licensed)
Array.prototype.remove = function(from, to) {
  var rest = this.slice((to || from) + 1 || this.length);
  this.length = from < 0 ? this.length + from : from;
  return this.push.apply(this, rest);

and here's some examples of how it could be used:

// Remove the second item from the array
// Remove the second-to-last item from the array
// Remove the second and third items from the array
// Remove the last and second-to-last items from the array

John's website

Run a Java Application as a Service on Linux

I wrote another simple wrapper here:

case $1 in
        echo "Starting $SERVICE_NAME ..."
        if [ ! -f $PID_PATH_NAME ]; then
            nohup java -jar $PATH_TO_JAR /tmp 2>> /dev/null >> /dev/null &
            echo $! > $PID_PATH_NAME
            echo "$SERVICE_NAME started ..."
            echo "$SERVICE_NAME is already running ..."
        if [ -f $PID_PATH_NAME ]; then
            PID=$(cat $PID_PATH_NAME);
            echo "$SERVICE_NAME stoping ..."
            kill $PID;
            echo "$SERVICE_NAME stopped ..."
            rm $PID_PATH_NAME
            echo "$SERVICE_NAME is not running ..."
        if [ -f $PID_PATH_NAME ]; then
            PID=$(cat $PID_PATH_NAME);
            echo "$SERVICE_NAME stopping ...";
            kill $PID;
            echo "$SERVICE_NAME stopped ...";
            rm $PID_PATH_NAME
            echo "$SERVICE_NAME starting ..."
            nohup java -jar $PATH_TO_JAR /tmp 2>> /dev/null >> /dev/null &
            echo $! > $PID_PATH_NAME
            echo "$SERVICE_NAME started ..."
            echo "$SERVICE_NAME is not running ..."

You can follow a full tutorial for init.d here and for systemd (ubuntu 16+) here

If you need the output log replace the 2

nohup java -jar $PATH_TO_JAR /tmp 2>> /dev/null >> /dev/null &

lines for

nohup java -jar $PATH_TO_JAR >> myService.out 2>&1&

jQuery scroll() detect when user stops scrolling

This detects the scroll stop after 1 milisecond (or change it) using a global timer:

var scrollTimer;

    //Do  what you want whilst scrolling

function afterScroll(){
    //I catched scroll stop.

Mod in Java produces negative numbers

if b > 0:
    int mod = (mod = a % b) < 0 ? a + b : a;

Doesn't use the % operator twice.

C++ equivalent of Java's toString?

As an extension to what John said, if you want to extract the string representation and store it in a std::string do this:

#include <sstream>    
// ...
// Suppose a class A
A a;
std::stringstream sstream;
sstream << a;
std::string s = sstream.str(); // or you could use sstream >> s but that would skip out whitespace

std::stringstream is located in the <sstream> header.

How to create an integer array in Python?

import numpy as np


An alternative for casting the type when the array is made.

Phone number validation Android

Here is how you can do it succinctly in Kotlin:

fun String.isPhoneNumber() =
            length in 4..10 && all { it.isDigit() }

Binding ng-model inside ng-repeat loop in AngularJS

For each iteration of the ng-repeat loop, line is a reference to an object in your array. Therefore, to preview the value, use {{line.text}}.

Similarly, to databind to the text, databind to the same: ng-model="line.text". You don't need to use value when using ng-model (actually you shouldn't).


For a more in-depth look at scopes and ng-repeat, see What are the nuances of scope prototypal / prototypical inheritance in AngularJS?, section ng-repeat.

Bootstrap: How do I identify the Bootstrap version?

That comment looks like it is a custom version of Bootstrap v2.3.3, here is the default header in the .css, notice the last comment line:

 * Bootstrap v2.3.2
 * Copyright 2013 Twitter, Inc
 * Licensed under the Apache License v2.0
 * Designed and built with all the love in the world by @mdo and @fat.

What are you trying to accomplish? If it's customization then you have a set of files to work with though that seems like a bad idea. Otherwise, I would suggest going with the full build of v4.1.x since that is the current release.

How to set host_key_checking=false in ansible inventory file?

Due to the fact that I answered this in 2014, I have updated my answer to account for more recent versions of ansible.

Yes, you can do it at the host/inventory level (Which became possible on newer ansible versions) or global level:


Add the following.

ansible_ssh_common_args='-o StrictHostKeyChecking=no'


Add the following.

ansible_ssh_extra_args='-o StrictHostKeyChecking=no'

hosts/inventory options will work with connection type ssh and not paramiko. Some people may strongly argue that inventory and hosts is more secure because the scope is more limited.


Ansible User Guide - Host Key Checking

  • You can do it either in the /etc/ansible/ansible.cfg or ~/.ansible.cfg file:

    host_key_checking = False
  • Or you can setup and env variable (this might not work on newer ansible versions):


"VT-x is not available" when I start my Virtual machine

Are you sure your processor supports Intel Virtualization (VT-x) or AMD Virtualization (AMD-V)?

Here you can find Hardware-Assisted Virtualization Detection Tool ( which will tell you if your hardware supports VT-x.

Alternatively you can find your processor here: All AMD processors since 2006 supports Virtualization.

How to add a “readonly” attribute to an <input>?

For enabling readonly:


For disabling readonly


Returning JSON from a PHP Script

A complete piece of nice and clear PHP code returning JSON is:

$option = $_GET['option'];

if ( $option == 1 ) {
    $data = [ 'a', 'b', 'c' ];
    // will encode to JSON array: ["a","b","c"]
    // accessed as example in JavaScript like: result[1] (returns "b")
} else {
    $data = [ 'name' => 'God', 'age' => -1 ];
    // will encode to JSON object: {"name":"God","age":-1}  
    // accessed as example in JavaScript like: or result['name'] (returns "God")

header('Content-type: application/json');
echo json_encode( $data );

Laravel - htmlspecialchars() expects parameter 1 to be string, object given

Laravel - htmlspecialchars() expects parameter 1 to be string, object given.

thank me latter.........................

when you send or get array from contrller or function but try to print as single value or single variable in laravel blade file so it throws an error

->use any think who convert array into string it work.

solution: 1)run the foreach loop and get single single value and print. 2)The implode() function returns a string from the elements of an array. {{ implode($your_variable,',') }}

implode is best way to do it and its 100% work.

Why is access to the path denied?

An UnauthorizedAccessException exception is thrown when the operating system denies access because of an I/O error or a security error.

If you are attempting to access a file or registry key, make sure it is not read-only.

How does HttpContext.Current.User.Identity.Name know which usernames exist?

The HttpContext.Current.User.Identity.Name returns null

This depends on whether the authentication mode is set to Forms or Windows in your web.config file.

For example, if I write the authentication like this:

<authentication mode="Forms"/>

Then because the authentication mode="Forms", I will get null for the username. But if I change the authentication mode to Windows like this:

<authentication mode="Windows"/>

I can run the application again and check for the username, and I will get the username successfully.

For more information, see System.Web.HttpContext.Current.User.Identity.Name Vs System.Environment.UserName in ASP.NET.

Error when checking Java version: could not find java.dll

Reinstall JDK and set system variable JAVA_HOME on your JDK. (e.g. C:\tools\jdk7)
And add JAVA_HOME variable to your PATH system variable

Type in command line

echo %JAVA_HOME%


java -version

To verify whether your installation was done successfully.

This problem generally occurs in Windows when your "Java Runtime Environment" registry entry is missing or mismatched with the installed JDK. The mismatch can be due to multiple JDKs.

Steps to resolve:

  1. Open the Run window:

    Press windows+R

  2. Open registry window:

    Type regedit and enter.


  4. If Java Runtime Environment is not present inside JavaSoft, then create a new Key and give the name Java Runtime Environment.

  5. For Java Runtime Environment create "CurrentVersion" String Key and give appropriate version as value:

JRE regedit entry

  1. Create a new subkey of 1.8.

  2. For 1.8 create a String Key with name JavaHome with the value of JRE home:

    JRE regedit entry 2


How to get Android application id?

Package name is your android app id .

String appId = BuildConfig.APPLICATION_ID


App Id = com.whatsapp

How can I check if a key exists in a dictionary?

If you want to retrieve the key's value if it exists, you can also use

    value = a[key]
except KeyError:
    # Key is not present

If you want to retrieve a default value when the key does not exist, use value = a.get(key, default_value). If you want to set the default value at the same time in case the key does not exist, use value = a.setdefault(key, default_value).

Excel error HRESULT: 0x800A03EC while trying to get range with cell's name

Using Dominic's answer I found the answer to my problem specifically was an invalid DateTiime in the source data before it was applied to the range. Somewhere between the database, .NET and Excel the conversion of the date defaulted down to "1/1/1899 12:00:00 AM". I had to check it and convert it to an empty string and it fixed it for me.

if (objectArray[row, col].ToString() == "1/1/1899 12:00:00 AM")
    objectArray[row, col] = string.Empty;

This is probably a pretty specific example but hopefully it will save somebody else some time if they are trying to track down a piece of invalid data.

Using Math.round to round to one decimal place?

If you need this and similar operations more often, it may be more convenient to find the right library instead of implementing it yourself.

Here are one-liners solving your question from Apache Commons Math using Precision, Colt using Functions, and Weka using Utils:

double value = 540.512 / 1978.8 * 100;
// Apache commons math
double rounded1 = Precision.round(value, 1);
double rounded2 = Precision.round(value, 1, BigDecimal.ROUND_HALF_UP);
// Colt
double rounded3 = Functions.round(0.1).apply(value)
// Weka
double rounded4 = Utils.roundDouble(value, 1)

Maven dependencies:




Google reCAPTCHA: How to get user response and validate in the server side?

Here is complete demo code to understand client side and server side process. you can copy paste it and just replace google site key and google secret key.

      //  echo '<pre>'; print_r($_REQUEST); die('END');
        $post = [
            'secret' => 'Your Secret key',
            'response' => $_REQUEST['g-recaptcha-response'],
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL,"");
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

        $server_output = curl_exec($ch);

        curl_close ($ch);
        echo '<pre>'; print_r($server_output); die('ss');
    <title>reCAPTCHA demo: Explicit render for multiple widgets</title>
    <script type="text/javascript">
      var site_key = 'Your Site key';
      var verifyCallback = function(response) {
      var widgetId1;
      var widgetId2;
      var onloadCallback = function() {
        // Renders the HTML element with id 'example1' as a reCAPTCHA widget.
        // The id of the reCAPTCHA widget is assigned to 'widgetId1'.
        widgetId1 = grecaptcha.render('example1', {
          'sitekey' : site_key,
          'theme' : 'light'
        widgetId2 = grecaptcha.render(document.getElementById('example2'), {
          'sitekey' : site_key
        grecaptcha.render('example3', {
          'sitekey' : site_key,
          'callback' : verifyCallback,
          'theme' : 'dark'
    <!-- The g-recaptcha-response string displays in an alert message upon submit. -->
    <form action="javascript:alert(grecaptcha.getResponse(widgetId1));">
      <div id="example1"></div>
      <input type="submit" value="getResponse">
    <!-- Resets reCAPTCHA widgetId2 upon submit. -->
    <form action="javascript:grecaptcha.reset(widgetId2);">
      <div id="example2"></div>
      <input type="submit" value="reset">
    <!-- POSTs back to the page's URL upon submit with a g-recaptcha-response POST parameter. -->
    <form action="?" method="POST">
      <div id="example3"></div>
      <input type="submit" value="Submit">
    <script src=""
        async defer>

The system cannot find the file specified in java

How are you running the program?

It's not the java file that is being ran but rather the .class file that is created by compiling the java code. You will either need to specify the absolute path like user1420750 says or a relative path to your System.getProperty("user.dir") directory. This should be the working directory or the directory you ran the java command from.

Redirect to external URL with return in laravel

You can use Redirect::away($url)

How to display a JSON representation and not [Object Object] on the screen

There are 2 ways in which you can get the values:-

  1. Access the property of the object using dot notation ( .
  2. Access the property of the object by passing in key value for example obj["property"]

How can I disable the Maven Javadoc plugin from the command line?

You can use the maven.javadoc.skip property to skip execution of the plugin, going by the Mojo's javadoc. You can specify the value as a Maven property:


or as a command-line argument: -Dmaven.javadoc.skip=true, to skip generation of the Javadocs.

Auto generate function documentation in Visual Studio

Make that "three single comment-markers"

In C# it's ///

which as default spits out:

/// <summary>
/// </summary>
/// <returns></returns>

Here's some tips on editing VS templates.

How to create a function in a cshtml template?

You can use the @helper Razor directive:

@helper WelcomeMessage(string username)
    <p>Welcome, @username.</p>

Then you invoke it like this:

@WelcomeMessage("John Smith")

connecting to phpMyAdmin database with PHP/MySQL

$db = new mysqli('Server_Name', 'Name', 'password', 'database_name');

How to set the text color of TextView in code?

getColor() is depreceted

So try this way:

 tv_title.setTextColor(ContextCompat.getColor(getApplicationContext(), R.color.sf_white));

How to have multiple conditions for one if statement in python

I would use

def example(arg1, arg2, arg3):
     if arg1 == 1 and arg2 == 2 and arg3 == 3:
          print("Example Text")

The and operator is identical to the logic gate with the same name; it will return 1 if and only if all of the inputs are 1. You can also use or operator if you want that logic gate.

EDIT: Actually, the code provided in your post works fine with me. I don't see any problems with that. I think that this might be a problem with your Python, not the actual language.

Changing default startup directory for command prompt in Windows 7

Edit: It actually seems that editing the file shortcut breaks the Win+x, c key shortcut. (Moral of the story: only change system files you know how to fix! Eventually after a Windows update it repaired itself.)

What I ended up doing is creating a new customized Command Prompt shortcut in the start folder and pinned to the taskbar that I launch instead of cmd.exe

As other answers point out, changing the registry Autorun cmd start location is a bad idea because it silently will break other programs that shell out for tasks, like Visual Studio Code.

You should just change whatever shortcut you use to open cmd to have a Start In entry.

If you use Win+x, c to launch cmd, you can edit the Start In for

"%LOCALAPPDATA%\Microsoft\Windows\WinX\Group3\02 - Command Prompt.lnk"

Trying to get property of non-object in

Check the manual for mysql_fetch_object(). It returns an object, not an array of objects.

I'm guessing you want something like this

$results = mysql_query("SELECT * FROM sidemenu WHERE `menu_id`='".$menu."' ORDER BY `id` ASC LIMIT 1", $con);

$sidemenus = array();
while ($sidemenu = mysql_fetch_object($results)) {
    $sidemenus[] = $sidemenu;

Might I suggest you have a look at PDO. PDOStatement::fetchAll(PDO::FETCH_OBJ) does what you assumed mysql_fetch_object() to do

Cleaning up old remote git branches

# First use prune --dry-run to filter+delete the local branches
git remote prune origin --dry-run \
  | grep origin/ \
  | sed 's,.*origin/,,g' \
  | xargs git branch -D

# Second delete the remote refs without --dry-run
git remote prune origin

Prune the same branches from local- and remote-refs(in my example from origin).

How to use paginator from material angular?

based on Wesley Coetzee's answer i wrote this. Hope it can help anyone googling this issue. I had bugs with swapping the paginator size in the middle of the list that's why i submit my answer:

Paginator html and list

<mat-paginator [length]="localNewspapers.length" pageSize=20
               (page)="getPaginatorData($event)" [pageSizeOptions]="[10, 20, 30]"
   <app-newspaper-pagi-item *ngFor="let paper of (localNewspapers | 
                         slice: lowValue : highValue)"

Component logic

import {Component, Input, OnInit} from "@angular/core";
import {PageEvent} from "@angular/material";

  selector: 'app-uniques-newspaper-list',
  templateUrl: './newspaper-uniques-list.component.html',
export class NewspaperUniquesListComponent implements OnInit {
  lowValue: number = 0;
  highValue: number = 20;

  // used to build an array of papers relevant at any given time
  public getPaginatorData(event: PageEvent): PageEvent {
    this.lowValue = event.pageIndex * event.pageSize;
    this.highValue = this.lowValue + event.pageSize;
    return event;


Why and how to fix? IIS Express "The specified port is in use"

The error message should tell you which application is already using the port - in my case it was explorer.exe, so it was just a case of restarting explorer from task manager.

Login failed for user 'DOMAIN\MACHINENAME$'

Basically to resolve this we need to have some set up like

  • Web App Running under ApplicationPoolIdentity
  • Web Application connecting to databases through ADO.Net using Windows Authentication in the connection string

The connection string used with Windows authentication include either Trusted_Connection=Yesattribute or the equivalent attribute Integrated Security=SSPI in Web.config file

My database connection is in Windows Authentication mode. So I resolved it by simply changing the Application Pools Identity from ApplicationPoolIdentity to my domain log in credentials DomainName\MyloginId


  1. Click on Application Pools
  2. Select Name of your application

  3. Go to Advanced Setting

  4. Expand Process Model and click Identity. Click three dot on right end.
  5. Click Set... button and Provide your domain log in credentials

For me it was resolved.

Note: In Production or IT environment, you might have service account under same domain for app pool identity. If so, use service account instead of your login.

Best way to Bulk Insert from a C# DataTable

If using SQL Server, SqlBulkCopy.WriteToServer(DataTable)

Or also with SQL Server, you can write it to a .csv and use BULK INSERT

If using MySQL, you could write it to a .csv and use LOAD DATA INFILE

If using Oracle, you can use the array binding feature of ODP.NET

If SQLite:

Ansible: copy a directory content to another directory

I got involved whole a day, too! and finally found the solution in shell command instead of copy: or command: as below:

- hosts: remote-server-name
  gather_facts: no
    src_path: "/path/to/source/"
    des_path: "/path/to/dest/"
  - name: Ansible copy files remote to remote
    shell: 'cp -r {{ src_path }}/. {{ des_path }}'

strictly notice to: 1. src_path and des_path end by / symbol 2. in shell command src_path ends by . which shows all content of directory 3. I used my remote-server-name both in hosts: and execute shell section of jenkins, instead of remote_src: specifier in playbook.

I guess it is a good advice to run below command in Execute Shell section in jenkins:

ansible-playbook  copy-payment.yml -i remote-server-name

Return 0 if field is null in MySQL

None of the above answers were complete for me. If your field is named field, so the selector should be the following one:

IFNULL(`field`,0) AS field

For example in a SELECT query:

SELECT IFNULL(`field`,0) AS field, `otherfield` FROM `mytable`

Hope this can help someone to not waste time.

Reverse a string in Python

You can use the reversed function with a list comprehesive. But I don't understand why this method was eliminated in python 3, was unnecessarily.

string = [ char for char in reversed(string)]

Check whether a table contains rows or not sql server 2005

Also, you can use exists

select case when exists (select 1 from table) 
          then 'contains rows' 
          else 'doesnt contain rows' 

or to check if there are child rows for a particular record :

select * from Table t1
where exists(
select 1 from ChildTable t2
where = t2.parentid)

or in a procedure

if exists(select 1 from table)
 -- do stuff

In PANDAS, how to get the index of a known value?

To get the index by value, simply add .index[0] to the end of a query. This will return the index of the first row of the result...

So, applied to your dataframe:

In [1]: a[a['c2'] == 1].index[0]     In [2]: a[a['c1'] > 7].index[0]   
Out[1]: 0                            Out[2]: 4                         

Where the query returns more than one row, the additional index results can be accessed by specifying the desired index, e.g. .index[n]

In [3]: a[a['c2'] >= 7].index[1]     In [4]: a[(a['c2'] > 1) & (a['c1'] < 8)].index[2]  
Out[3]: 4                            Out[4]: 3 

Add JsonArray to JsonObject

Your list:

List<MyCustomObject> myCustomObjectList;

Your JSONArray:

// Don't need to loop through it. JSONArray constructor do it for you.
new JSONArray(myCustomObjectList)

Your response:

return new JSONObject().put("yourCustomKey", new JSONArray(myCustomObjectList));

Your post/put http body request would be like this:

        "yourCustomKey: [
               "myCustomObjectProperty": 1
               "myCustomObjectProperty": 2

python pandas convert index to datetime

I just give other option for this question - you need to use '.dt' in your code:

import pandas as pd_x000D_
df.index = pd.to_datetime(df.index)_x000D_
#for get year_x000D_
#for get month_x000D_
#for get day_x000D_
#for get hour_x000D_
#for get minute_x000D_

How do I dynamically set the selected option of a drop-down list using jQuery, JavaScript and HTML?

Here it goes.

// Select by value_x000D_
// Select by text_x000D_
<script src=""></script>_x000D_
<select name="options">_x000D_
      <option value="1">First</option>_x000D_
      <option value="2">Second</option>_x000D_
      <option value="3">Third</option>_x000D_

Create a batch file to copy and rename file

Make a bat file with the following in it:

copy /y C:\temp\log1k.txt C:\temp\log1k_copied.txt

However, I think there are issues if there are spaces in your directory names. Notice this was copied to the same directory, but that doesn't matter. If you want to see how it runs, make another bat file that calls the first and outputs to a log:

C:\temp\test.bat > C:\temp\test.log

(assuming the first bat file was called test.bat and was located in that directory)

How do I print the elements of a C++ vector in GDB?

With GCC 4.1.2, to print the whole of a std::vector<int> called myVector, do the following:

print *(myVector._M_impl._M_start)@myVector.size()

To print only the first N elements, do:

print *(myVector._M_impl._M_start)@N


This is probably heavily dependent on your compiler version, but for GCC 4.1.2, the pointer to the internal array is:


And the GDB command to print N elements of an array starting at pointer P is:

print P@N

Or, in a short form (for a standard .gdbinit):

p P@N

How to do an Integer.parseInt() for a decimal number?

use this one

int number = (int) Double.parseDouble(s);

Looping through list items with jquery

   <script src=""></script>
      $(document).ready(function() {
       var name = $("#name").val();
       var amount =$("#number").val();
       var gst=(amount)*(0.18);

       var total=parseInt(amount)+parseInt(gst);
       $(".myTable tbody").append("<tr><td></td><td>"+name+"</td><td>"+amount+"</td><td>"+gst+"</td><td>"+total+"</td></tr>");



       $("#formdata").on('submit', '.myTable', function () {

                   var sum = 0;

          $(".myTable tbody tr").each(function () {
                    var getvalue = $(this).val();
                    if ($.isNumeric(getvalue))
                        sum += parseFloat(getvalue);







       <form id="formdata">  

                           <span>Product Name</span>
                           <input type="text" id="name">

                           <span>Product Amount</span>
                           <input type="text" id="number">
                           <center><button type="submit" class="adddata">Add</button></center>

      <table class="myTable" border="1px" width="300px">


                 <td class="total"></td>
                 <td class="total"></td>



React-Router External link

I was able to achieve a redirect in react-router-dom using the following

<Route exact path="/" component={() => <Redirect to={{ pathname: '/YourRoute' }} />} />

For my case, I was looking for a way to redirect users whenever they visit the root URL to somewhere else within the app so the above helped.

Get all messages from Whatsapp

I'm not sure if WhatsApp really stores it's stuff in a sqlite database stored in the private app space but it may be worth a try to do the same I suggested here. You will need root access for this.

Git Push ERROR: Repository not found

If anybody faced the issue at check if you have accepted an invitation after repo owner allowed commits to you. Until you accept invitation repo will be invisible for you. So you'll get ERROR: Repository not found.

How to connect to MongoDB in Windows?

For this error, if you are using windows 7 or windows server 2008 R2, the problem could be that you have to install a microsoft hotfix.

Refer to this link:

How to comment and uncomment blocks of code in the Office VBA Editor

Steps to comment / uncommented

Press alt + f11/ Developer tab visual basic editor view tab - toolbar - edit - comments.

CSS hover vs. JavaScript mouseover

A very big difference is that ":hover" state is automatically deactivated when the mouse moves out of the element. As a result any styles that are applied on hover are automatically reversed. On the other hand, with the javascript approach, you would have to define both "onmouseover" and "onmouseout" events. If you only define "onmouseover" the styles that are applied "onmouseover" will persist even after you mouse out unless you have explicitly defined "onmouseout".

How do I use $scope.$watch and $scope.$apply in AngularJS?

In AngularJS, we update our models, and our views/templates update the DOM "automatically" (via built-in or custom directives).

$apply and $watch, both being Scope methods, are not related to the DOM.

The Concepts page (section "Runtime") has a pretty good explanation of the $digest loop, $apply, the $evalAsync queue and the $watch list. Here's the picture that accompanies the text:

$digest loop

Whatever code has access to a scope – normally controllers and directives (their link functions and/or their controllers) – can set up a "watchExpression" that AngularJS will evaluate against that scope. This evaluation happens whenever AngularJS enters its $digest loop (in particular, the "$watch list" loop). You can watch individual scope properties, you can define a function to watch two properties together, you can watch the length of an array, etc.

When things happen "inside AngularJS" – e.g., you type into a textbox that has AngularJS two-way databinding enabled (i.e., uses ng-model), an $http callback fires, etc. – $apply has already been called, so we're inside the "AngularJS" rectangle in the figure above. All watchExpressions will be evaluated (possibly more than once – until no further changes are detected).

When things happen "outside AngularJS" – e.g., you used bind() in a directive and then that event fires, resulting in your callback being called, or some jQuery registered callback fires – we're still in the "Native" rectangle. If the callback code modifies anything that any $watch is watching, call $apply to get into the AngularJS rectangle, causing the $digest loop to run, and hence AngularJS will notice the change and do its magic.

Jquery UI tooltip does not support html content

Replacing the \n or the escaped <br/> does the trick while keeping the rest of the HTML escaped:

    content: function() {
        var title = $(this).attr("title") || "";
        return $("<a>").text(title).html().replace(/&lt;br *\/?&gt;/, "<br/>");

How do I give ASP.NET permission to write to a folder in Windows 7?

My immediate solution (since I couldn't find the ASP.NET worker process) was to give write (that is, Modify) permission to IIS_IUSRS. This worked. I seem to recall that in WinXP I had to specifically given the ASP.NET worker process write permission to accomplish this. Maybe my memory is faulty, but anyway...

@DraganRadivojevic wrote that he thought this was dangerous from a security viewpoint. I do not disagree, but since this was my workstation and not a network server, it seemed relatively safe. In any case, his answer is better and is what I finally settled on after chasing down a fail-path due to not specifying the correct domain for the AppPool user.

What is the use of the @ symbol in PHP?

The @ symbol is the error control operator (aka the "silence" or "shut-up" operator). It makes PHP suppress any error messages (notice, warning, fatal, etc) generated by the associated expression. It works just like a unary operator, for example, it has a precedence and associativity. Below are some examples:

@echo 1 / 0;
// generates "Parse error: syntax error, unexpected T_ECHO" since 
// echo is not an expression

echo @(1 / 0);
// suppressed "Warning: Division by zero"

@$i / 0;
// suppressed "Notice: Undefined variable: i"
// displayed "Warning: Division by zero"

@($i / 0);
// suppressed "Notice: Undefined variable: i"
// suppressed "Warning: Division by zero"

$c = @$_POST["a"] + @$_POST["b"];
// suppressed "Notice: Undefined index: a"
// suppressed "Notice: Undefined index: b"

$c = @foobar();
echo "Script was not terminated";
// suppressed "Fatal error: Call to undefined function foobar()"
// however, PHP did not "ignore" the error and terminated the
// script because the error was "fatal"

What exactly happens if you use a custom error handler instead of the standard PHP error handler:

If you have set a custom error handler function with set_error_handler() then it will still get called, but this custom error handler can (and should) call error_reporting() which will return 0 when the call that triggered the error was preceded by an @.

This is illustrated in the following code example:

function bad_error_handler($errno, $errstr, $errfile, $errline, $errcontext) {
    echo "[bad_error_handler]: $errstr";
    return true;
echo @(1 / 0);
// prints "[bad_error_handler]: Division by zero"

The error handler did not check if @ symbol was in effect. The manual suggests the following:

function better_error_handler($errno, $errstr, $errfile, $errline, $errcontext) {
    if(error_reporting() !== 0) {
        echo "[better_error_handler]: $errstr";
    // take appropriate action
    return true;

Rails where condition using NOT NIL

For Rails4:

So, what you're wanting is an inner join, so you really should just use the joins predicate:


  Select * from Foo Inner Join Bars ...

But, for the record, if you want a "NOT NULL" condition simply use the not predicate:

Foo.includes(:bar).where.not(bars: {id: nil})

Select * from Foo Left Outer Join Bars on .. WHERE IS NOT NULL

Note that this syntax reports a deprecation (it talks about a string SQL snippet, but I guess the hash condition is changed to string in the parser?), so be sure to add the references to the end:

Foo.includes(:bar).where.not(bars: {id: nil}).references(:bar)

DEPRECATION WARNING: It looks like you are eager loading table(s) (one of: ....) that are referenced in a string SQL snippet. For example:

Post.includes(:comments).where("comments.title = 'foo'")

Currently, Active Record recognizes the table in the string, and knows to JOIN the comments table to the query, rather than loading comments in a separate query. However, doing this without writing a full-blown SQL parser is inherently flawed. Since we don't want to write an SQL parser, we are removing this functionality. From now on, you must explicitly tell Active Record when you are referencing a table from a string:

Post.includes(:comments).where("comments.title = 'foo'").references(:comments)

Using variables inside a bash heredoc

As a late corolloary to the earlier answers here, you probably end up in situations where you want some but not all variables to be interpolated. You can solve that by using backslashes to escape dollar signs and backticks; or you can put the static text in a variable.

Name='Rich Ba$tard'
cat <<____HERE
$Name, you can win a lot of $dough this week!
Notice that \`backticks' need escaping if you want
literal text, not `pwd`, just like in variables like
\$HOME (current value: $HOME)


Note that any of the quoting mechanisms -- \____HERE or "____HERE" or '____HERE' -- will disable all variable interpolation, and turn the here-document into a piece of literal text.

A common task is to combine local variables with script which should be evaluated by a different shell, programming language, or remote host.

ssh -t remote <<:
    echo "$local is the value from the host which ran the ssh command"
    # Prevent here doc from expanding locally; remote won't see backslash
    # Same here
    echo "\$remote is the value from the host we ssh:ed to"

What is the preferred Bash shebang?

/bin/sh is usually a link to the system's default shell, which is often bash but on, e.g., Debian systems is the lighter weight dash. Either way, the original Bourne shell is sh, so if your script uses some bash (2nd generation, "Bourne Again sh") specific features ([[ ]] tests, arrays, various sugary things, etc.), then you should be more specific and use the later. This way, on systems where bash is not installed, your script won't run. I understand there may be an exciting trilogy of films about this evolution...but that could be hearsay.

Also note that when evoked as sh, bash to some extent behaves as POSIX standard sh (see also the GNU docs about this).

How to make Google Fonts work in IE?

While Yi Jiang's solution may work, I don't believe abandoning the Google Web Font API is the right answer here. We serve a local jQuery file when it's not properly loaded from the CDN, right?

<script src="//"></script>
<script>window.jQuery || document.write('<script src="/js/jquery-1.9.0.min.js"><\/script>')</script>

So why wouldn't we do the same for fonts, specifically for < IE9?

<link href=',400italic,700' rel='stylesheet' type='text/css'>
<!--[if lt IE 9]><link href='/css/fonts.css' rel='stylesheet' type='text/css'><![endif]-->

Here's my process when using custom fonts:

  1. Download the font's ZIP folder from Google, and use Font Squirrel's @font-face Generator to create the local web font.
  2. Create a fonts.css file that calls the newly created, locally hosted font files (only linking to the file if < IE9, as shown above). NOTE: The @font-face Generator creates this file for you.

    @font-face {
      font-family: 'cardoitalic';
      src: url('cardo-italic-webfont.eot');
      src: url('cardo-italic-webfont.eot?#iefix') format('embedded-opentype'),
        url('cardo-italic-webfont.woff') format('woff'),
        url('cardo-italic-webfont.ttf') format('truetype'),
        url('cardo-italic-webfont.svg#cardoitalic') format('svg');
      font-weight: normal;
      font-style: normal;
    @font-face {
      font-family: 'cardobold';
      src: url('cardo-bold-webfont.eot');
      src: url('cardo-bold-webfont.eot?#iefix') format('embedded-opentype'),
        url('cardo-bold-webfont.woff') format('woff'),
        url('cardo-bold-webfont.ttf') format('truetype'),
        url('cardo-bold-webfont.svg#cardobold') format('svg');
      font-weight: normal;
      font-style: normal;
    @font-face {
      font-family: 'cardoregular';
      src: url('cardo-regular-webfont.eot');
      src: url('cardo-regular-webfont.eot?#iefix') format('embedded-opentype'),
         url('cardo-regular-webfont.woff') format('woff'),
         url('cardo-regular-webfont.ttf') format('truetype'),
         url('cardo-regular-webfont.svg#cardoregular') format('svg');
      font-weight: normal;
      font-style: normal;
  3. Using IE conditional classes in your main stylesheet to avoide faux weights and styles, your font styles might look like this:

    .lt-ie9 h1{
    .lt-ie9 h2{
    .lt-ie9 strong,
    .lt-ie9 b{

Sure, it's a little extra work, but haven't we come to expect this from IE? Besides, it becomes second-nature after awhile.

How to get the new value of an HTML input after a keypress has modified it?

        function callme(field) {
            alert("field:" + field.value);
        <form name="f1">
            <input type="text" onkeyup="callme(this);" name="text1">

It looks like you can use the onkeyup to get the new value of the HTML input control. Hope it helps.

How does tuple comparison work in Python?

Tuples are compared position by position: the first item of the first tuple is compared to the first item of the second tuple; if they are not equal (i.e. the first is greater or smaller than the second) then that's the result of the comparison, else the second item is considered, then the third and so on.

See Common Sequence Operations:

Sequences of the same type also support comparisons. In particular, tuples and lists are compared lexicographically by comparing corresponding elements. This means that to compare equal, every element must compare equal and the two sequences must be of the same type and have the same length.

Also Value Comparisons for further details:

Lexicographical comparison between built-in collections works as follows:

  • For two collections to compare equal, they must be of the same type, have the same length, and each pair of corresponding elements must compare equal (for example, [1,2] == (1,2) is false because the type is not the same).
  • Collections that support order comparison are ordered the same as their first unequal elements (for example, [1,2,x] <= [1,2,y] has the same value as x <= y). If a corresponding element does not exist, the shorter collection is ordered first (for example, [1,2] < [1,2,3] is true).

If not equal, the sequences are ordered the same as their first differing elements. For example, cmp([1,2,x], [1,2,y]) returns the same as cmp(x,y). If the corresponding element does not exist, the shorter sequence is considered smaller (for example, [1,2] < [1,2,3] returns True).

Note 1: < and > do not mean "smaller than" and "greater than" but "is before" and "is after": so (0, 1) "is before" (1, 0).

Note 2: tuples must not be considered as vectors in a n-dimensional space, compared according to their length.

Note 3: referring to question do not think that a tuple is "greater" than another only if any element of the first is greater than the corresponding one in the second.

How to display HTML tags as plain text

The native JavaScript approach -

('<strong>Look just ...</strong>').replace(/</g, '&lt;').replace(/>/g, '&gt;');


Reading file from Workspace in Jenkins with Groovy script

Based on your comments, you would be better off with Text-finder plugin.

It allows to search file(s), as well as console, for a regular expression and then set the build either unstable or failed if found.

As for the Groovy, you can use the following to access ${WORKSPACE} environment variable:
def workspace =["WORKSPACE"]

Function stoi not declared

I came across this error while working on a programming project in c++,

  1. atoi(),stoi() is not part of the old c++ library in g++ so use the below options while compiling g++ -std=c++11 -o my_app_code my_app_code.cpp
  2. Include the following file in your code #include < cstdlib >

This should take care of the errors

ASP.NET Core 1.0 on IIS error 502.5

I had the same issue when publishing the web app. If anybody still has this problem fixed it by changing {AppName}.runtimeconfig.json

  "runtimeOptions": {
    "framework": {
      "name": "Microsoft.NETCore.App",
      "version": "1.1.2"
    "configProperties": {
      "System.GC.Server": true

Change the version from "version": "1.1.2" to "version": "1.1.1" and everythign worked ok

adding multiple event listeners to one element

Maybe you can use a helper function like this:

// events and args should be of type Array
function addMultipleListeners(element,events,handler,useCapture,args){
  if (!(events instanceof Array)){
    throw 'addMultipleListeners: '+
          'please supply an array of eventstrings '+
          '(like ["click","mouseover"])';
  //create a wrapper to be able to use additional arguments
  var handlerFn = function(e){
    handler.apply(this, args && args instanceof Array ? args : []);
  for (var i=0;i<events.length;i+=1){

function handler(e) {
  // do things

// usage

[Edit nov. 2020] This answer is pretty old. The way I solve this nowadays is by using an actions object where handlers are specified per event type, a data-attribute for an element to indicate which action should be executed on it and one generic document wide handler method (so event delegation).

const firstElemHandler = (elem, evt) =>
  elem.textContent = `You ${evt.type === "click" ? "clicked" : "touched"}!`;
const actions = {
  click: {
  touchstart: {
  mouseover: {
    firstElemHandler: elem => elem.textContent = "Now ... click me!",
    outerHandling: elem => {
      console.log(`Hi from outerHandling, handle time ${
        new Date().toLocaleTimeString()}`);

Object.keys(actions).forEach(key => document.addEventListener(key, handle));

function handle(evt) {
  const origin ="[data-action]");
  return origin &&
    actions[evt.type] &&
    actions[evt.type][origin.dataset.action] &&
    actions[evt.type][origin.dataset.action](origin, evt) ||
[data-action]:hover {
  cursor: pointer;
<div data-action="outerHandling">
  <div id="first" data-action="firstElemHandler">
    <b>Hover, click or tap</b>
  this is handled too (on mouse over)

Using custom fonts using CSS?

there's also an interesting tool called CUFON. There's a demonstration of how to use it in this blog It's really simple and interesting. Also, it doesn't allow people to ctrl+c/ctrl+v the generated content.

iptables v1.4.14: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)

"IP conntrack functionality has some negative impact on venet performance (uo to about 10%), so they better be disabled by default." It's need for nat

React-Router open Link in new tab

We can use the following options:-

 // first option is:-
    <Link to="myRoute" params={myParams} target="_blank">

 // second option is:-
    var href = this.props.history.createHref('myRoute', myParams);
    <a href={href} target="_blank">

 //third option is:-
    var href = '/myRoute/' + + '/' +;
    <a href={href} target="_blank">

We can use either of three option to open in new tab by react routing.

Why is json_encode adding backslashes?

Just use the "JSON_UNESCAPED_SLASHES" Option (added after version 5.4).


Execute bash script from URL

Just combining amra and user77115's answers:

wget -qO- | bash -s -- -v -v

It executes the distant script passing it the -v -v options.

javascript regular expression to check for IP addresses

Try this one.. Source from here.


File Upload with Angular Material

Adding to all the answers above (which is why I made it a community wiki), it is probably best to mark any input<type="text"> with tabindex="-1", especially if using readonly instead of disabled (and perhaps the <input type="file">, although it should be hidden, it is still in the document, apparently). Labels did not act correctly when using the tab / enter key combinations, but the button did. So if you are copying one of the other solutions on this page, you may want to make those changes.

Inserting into Oracle and retrieving the generated sequence ID

You can do this with a single statement - assuming you are calling it from a JDBC-like connector with in/out parameters functionality:

insert into batch(batchid, batchname) 
values (batch_seq.nextval, 'new batch')
returning batchid into :l_batchid;

or, as a pl-sql script:

variable l_batchid number;

insert into batch(batchid, batchname) 
values (batch_seq.nextval, 'new batch')
returning batchid into :l_batchid;

select :l_batchid from dual;

Primary key or Unique index?

If something is a primary key, depending on your DB engine, the entire table gets sorted by the primary key. This means that lookups are much faster on the primary key because it doesn't have to do any dereferencing as it has to do with any other kind of index. Besides that, it's just theory.

Convert double to string C++?

In C++11, use std::to_string if you can accept the default format (%f).

storedCorrect[count]= "(" + std::to_string(c1) + ", " + std::to_string(c2) + ")";

Get Selected value from Multi-Value Select Boxes by jquery-select2?

Please, ckeck this simple example. You can get values in select2 multi.

var values = $('#id-select2-multi').val();

How to remove responsive features in Twitter Bootstrap 3?

To inactivate the non-desktop styles you just have to change 4 lines of code in the variables.less file. Set the screen width breakpoints in the variables.less file like this:

// Media queries breakpoints
// --------------------------------------------------

// Extra small screen / phone
// Note: Deprecated @screen-xs and @screen-phone as of v3.0.1
@screen-xs:                  1px;
@screen-xs-min:              @screen-xs;
@screen-phone:               @screen-xs-min;

// Small screen / tablet
// Note: Deprecated @screen-sm and @screen-tablet as of v3.0.1
@screen-sm:                  2px;
@screen-sm-min:              @screen-sm;
@screen-tablet:              @screen-sm-min;

// Medium screen / desktop
// Note: Deprecated @screen-md and @screen-desktop as of v3.0.1
@screen-md:                  3px;
@screen-md-min:              @screen-md;
@screen-desktop:             @screen-md-min;

// Large screen / wide desktop
// Note: Deprecated @screen-lg and @screen-lg-desktop as of v3.0.1
@screen-lg:                  9999px;
@screen-lg-min:              @screen-lg;
@screen-lg-desktop:          @screen-lg-min;

This sets the min-width on the desktop style media query lower so that it applies to all screen widths. Thanks to 2calledchaos for the improvement! Some base styles are defined in the mobile styles, so we need to be sure to include them.

Edit: chris notes that you can set these variables in the online less compiler on the bootstrap site

private final static attribute vs private final attribute

Static variable belongs to the class (which means all the objects share that variable). Non static variable belongs to each objects.

public class ExperimentFinal {

private final int a;
private static final int b = 999; 

public ExperimentFinal(int a) {
    this.a = a;
public int getA() {
    return a;
public int getB() {
    return b;
public void print(int a, int b) {
    System.out.println("final int: " + a + " \nstatic final int: " + b);
public static void main(String[] args) {
    ExperimentFinal test = new ExperimentFinal(9);
    test.print(test.getA(), test.getB());
} }

As you can see above example, for "final int" we can assign our variable for each instance (object) of the class, however for "static final int", we should assign a variable in the class (static variable belongs to the class).

Trigger 404 in Spring-MVC controller?

Simply you can use web.xml to add error code and 404 error page. But make sure 404 error page must not locate under WEB-INF.


This is the simplest way to do it but this have some limitation. Suppose if you want to add the same style for this page that you added other pages. In this way you can't to that. You have to use the @ResponseStatus(value = HttpStatus.NOT_FOUND)

How to capitalize the first letter of word in a string using Java?

Even for "simple" code, I would use libraries. The thing is not the code per se, but the already existing test cases covering exceptional cases. This could be null, empty strings, strings in other languages.

The word manipulation part has been moved out ouf Apache Commons Lang. It is now placed in Apache Commons Text. Get it via

You can use WordUtils.capitalize(String str) from Apache Commons Text. It is more powerful than you asked for. It can also capitalize fulle (e.g., fixing "oNe tousand only").

Since it works on complete text, one has to tell it to capitalize only the first word.

WordUtils.capitalize("one thousand only", new char[0]);

Full JUnit class to enable playing with the functionality:

package io.github.koppor;

import org.apache.commons.text.WordUtils;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.*;

class AppTest {

  void test() {
    assertEquals("One thousand only", WordUtils.capitalize("one thousand only", new char[0]));


Using Razor within JavaScript

None of the previous solutions work correctly... I have tried all the ways, but it did not give me the expected result... At last I found that there are some errors in the code... And the full code is given below.

<script type="text/javascript">

    var map = new google.maps.Map(document.getElementById('map'), {
        zoom: 10,
        center: new google.maps.LatLng(23.00, 90.00),
        mapTypeId: google.maps.MapTypeId.ROADMAP

    @foreach (var item in Model)
            var markerlatLng = new google.maps.LatLng(@(item.LATITUDE), @(item.LONGITUDE));
            var title = '@(item.EMP_ID)';
            var description = '@(item.TIME)';
            var contentString = '<h3>' + "Employee " +title+ " was here at "+description+ '</h3>' + '<p>'+" "+ '</p>'

            var infowindow = new google.maps.InfoWindow({
                // content: contentString

            var marker = new google.maps.Marker({
                position: markerlatLng,
                title: title,
                map: map,
                draggable: false,
                content: contentString

            google.maps.event.addListener(marker, 'click', (function (marker) {
                return function () {
          , marker);

Delete a database in phpMyAdmin

There are two ways for delete Database

  1. Run this SQL query -> DROP DATABASE database_name
  2. Click database_name -> Operations ->Remove Database

What is the best way to do a substring in a batch file?

As an additional info to Joey's answer, which isn't described in the help of set /? nor for /?.

%~0 expands to the name of the own batch, exactly as it was typed.
So if you start your batch it will be expanded as

%~0   - mYbAtCh
%~n0  - mybatch
%~nx0 - mybatch.bat

But there is one exception, expanding in a subroutine could fail

echo main- %~0
call :myFunction
exit /b

echo func - %~0
echo func - %~n0
exit /b

This results to

main - myBatch
Func - :myFunction
func - mybatch

In a function %~0 expands always to the name of the function, not of the batch file.
But if you use at least one modifier it will show the filename again!

How to call VS Code Editor from terminal / command line

I use the following command to load a project quickly (in linux)

  1. cd into the project cd /project
  2. run command code pwd

similar steps can be used in other Os too.

How can I remove the search bar and footer added by the jQuery DataTables plugin?

var table = $("#datatable").DataTable({
   "paging": false,
   "ordering": false,
   "searching": false

SQL conditional SELECT

Sounds like they want the ability to return only allowed fields, which means the number of fields returned also has to be dynamic. This will work with 2 variables. Anything more than that will be getting confusing.

IF (selectField1 = true AND selectField2 = true)
   SELECT Field1, Field2
   FROM Table
ELSE IF (selectField1 = true)
   SELECT Field1
   FROM Table
ELSE IF (selectField2 = true)
   SELECT Field2
   FROM Table

Dynamic SQL will help with multiples. This examples is assuming atleast 1 column is true.

DECLARE @sql varchar(MAX)
SET @sql = 'SELECT '
IF (selectField1 = true)
   SET @sql = @sql + 'Field1, '
IF (selectField2 = true)
   SET @sql = @sql + 'Field2, '
-- DROP ', '
@sql = SUBSTRING(@sql, 1, LEN(@sql)-2)

SET @sql = @sql + ' FROM Table'


Best way to retrieve variable values from a text file?

You can treat your text file as a python module and load it dynamically using imp.load_source:

import imp
imp.load_source( name, pathname[, file]) 


// mydata.txt
var1 = 'hi'
var2 = 'how are you?'
var3 = { 1:'elem1', 2:'elem2' }

// In your script file
def getVarFromFile(filename):
    import imp
    f = open(filename)
    global data
    data = imp.load_source('data', '', f)

# path to "config" file
print data.var1
print data.var2
print data.var3

How do I partially update an object in MongoDB so the new object will overlay / merge with the existing one

You should think about updating the object interchangeably and then simply store the object with the updated fields. Something like done below

function update(_id) {
    return new Promise((resolve, reject) => {

        ObjModel.findOne({_id}).exec((err, obj) => {

            if(err) return reject(err)

            obj = updateObject(obj, { 
                some_key: {
                    param2 : "val2_new",
                    param3 : "val3_new"

  , obj) => {
                if(err) return reject(err)

function updateObject(obj, data) {

    let keys = Object.keys(data)

    keys.forEach(key => {

        if(!obj[key]) obj[key] = data[key]

        if(typeof data[key] == 'object') 
            obj[key] = updateObject(obj[key], data[key])
            obj[key] = data[key]

    return obj

RabbitMQ / AMQP: single queue, multiple consumers for same message?

Fan out was clearly what you wanted. fanout

read rabbitMQ tutorial:

here's my example:


amqp.connect('amqp://<user>:<pass>@<host>:<port>', async (error0, connection) => {
    if (error0) {
      throw error0;
    console.log('RabbitMQ connected')
    try {
      // Create exchange for queues
      channel = await connection.createChannel()
      await channel.assertExchange(process.env.EXCHANGE_NAME, 'fanout', { durable: false });
      await channel.publish(process.env.EXCHANGE_NAME, '', Buffer.from('msg'))
    } catch(error) {


amqp.connect('amqp://<user>:<pass>@<host>:<port>', async (error0, connection) => {
    if (error0) {
      throw error0;
    console.log('RabbitMQ connected')
    try {
      // Create/Bind a consumer queue for an exchange broker
      channel = await connection.createChannel()
      await channel.assertExchange(process.env.EXCHANGE_NAME, 'fanout', { durable: false });
      const queue = await channel.assertQueue('', {exclusive: true})
      channel.bindQueue(queue.queue, process.env.EXCHANGE_NAME, '')

      console.log(" [*] Waiting for messages in %s. To exit press CTRL+C");
      channel.consume('', consumeMessage, {noAck: true});
    } catch(error) {

here is an example i found in the internet. maybe can also help.

Where's my invalid character (ORA-00911)

Of the top of my head, can you try to use the 'q' operator for the string literal

something like

insert all
  into domo_queries values (q'[select 
substr(to_char(max_data),1,4) as year,
substr(to_char(max_data),5,6) as month,
from dss_fin_user.acq_dashboard_src_load_success
where source = 'CHQ PeopleSoft FS']')
select * from dual;

Note that the single quotes of your predicate are not escaped, and the string sits between q'[...]'.

GridView - Show headers on empty data source

Use an EmptyDataTemplate like below. When your DataSource has no records, you will see your grid with headers, and the literal text or HTML that is inside the EmptyDataTemplate tags.

<asp:GridView ID="gvResults" AutoGenerateColumns="False" HeaderStyle-CssClass="tableheader" runat="server">
        <asp:Label ID="lblEmptySearch" runat="server">No Results Found</asp:Label>
        <asp:BoundField DataField="ItemId" HeaderText="ID" />
        <asp:BoundField DataField="Description" HeaderText="Description" />

Initializing array of structures

This is quite simple: my_data is a before defined structure type. So you want to declare an my_data-array of some elements, as you would do with

char a[] = { 'a', 'b', 'c', 'd' };

So the array would have 4 elements and you initialise them as

a[0] = 'a', a[1] = 'b', a[1] = 'c', a[1] ='d';

This is called a designated initializer (as i remember right).

and it just indicates that data has to be of type my_dat and has to be an array that needs to store so many my_data structures that there is a structure with each type member name Peter, James, John and Mike.

Sorting Values of Set

Use a SortedSet (TreeSet is the default one):

SortedSet<String> set=new TreeSet<String>();
List<String> list=new ArrayList<String>(set);

No extra sorting code needed.

Oh, I see you want a different sort order. Supply a Comparator to the TreeSet:

new TreeSet<String>(Comparator.comparing(Integer::valueOf));

Now your TreeSet will sort Strings in numeric order (which implies that it will throw exceptions if you supply non-numeric strings)


PHP string "contains"

You can use these string functions,

strstr — Find the first occurrence of a string

stristr — Case-insensitive strstr()

strrchr — Find the last occurrence of a character in a string

strpos — Find the position of the first occurrence of a substring in a string

strpbrk — Search a string for any of a set of characters

If that doesn't help then you should use preg regular expression

preg_match — Perform a regular expression match

How to append binary data to a buffer in node.js

Buffers are always of fixed size, there is no built in way to resize them dynamically, so your approach of copying it to a larger Buffer is the only way.

However, to be more efficient, you could make the Buffer larger than the original contents, so it contains some "free" space where you can add data without reallocating the Buffer. That way you don't need to create a new Buffer and copy the contents on each append operation.

Check for database connection, otherwise display message

Try this:

$servername   = "localhost";
$database = "database";
$username = "user";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password, $database);
// Check connection
if ($conn->connect_error) {
   die("Connection failed: " . $conn->connect_error);
  echo "Connected successfully";

how to permit an array with strong parameters

This seems like the relevant section of the docs:

The permitted scalar types are String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile and Rack::Test::UploadedFile.

To declare that the value in params must be an array of permitted scalar values map the key to an empty array:

params.permit(:id => [])

In my app, the category_ids are passed to the create action in an array

"category_ids"=>["", "2"],

Therefore, when declaring strong parameters, I explicitly set category_ids to be an array

params.require(:question).permit(:question_details, :question_content, :user_id, :accepted_answer_id, :province_id, :city, :category_ids => [])

Works perfectly now!

(IMPORTANT: As @Lenart notes in the comments, the array declarations must be at the end of the attributes list, otherwise you'll get a syntax error.)

Switch case with fallthrough?

Recent bash versions allow fall-through by using ;& in stead of ;;: they also allow resuming the case checks by using ;;& there.

for n in 4 14 24 34
  echo -n "$n = "
  case "$n" in
   3? )
     echo -n thirty-
     ;;&   #resume (to find ?4 later )
   "24" )
     echo -n twenty-
     ;&   #fallthru
   "4" | [13]4)
     echo -n four 
     ;;&  # resume ( to find teen where needed )
   "14" )
     echo -n teen

sample output

4 = four
14 = fourteen
24 = twenty-four
34 = thirty-four

WCF Service Client: The content type text/html; charset=utf-8 of the response message does not match the content type of the binding

Even if you don't use network proxy, turning 'Automatically detect settings' in proxy dialog makes this exception go off.

enter image description here

How can I do an asc and desc sort using underscore.js?

Underscore Mixins

Extending on @emil_lundberg's answer, you can also write a "mixin" if you're using Underscore to make a custom function for sorting if it's a kind of sorting you might repeat in an application somewhere.

For example, maybe you have a controller or view sorting results with sort order of "ASC" or "DESC", and you want to toggle between that sort, you could do something like this:


    sortByOrder: function(stooges, prop, order) {
      if (String(order) === "desc") {
          return _.sortBy(stooges, prop).reverse();
      } else if (String(order) === "asc") {
          return _.sortBy(stooges, prop);
      } else {
          return stooges;

Usage Example

var sort_order = "asc";
var stooges = [
  {name: 'moe', age: 40}, 
  {name: 'larry', age: 50}, 
  {name: 'curly', age: 60},
  {name: 'July', age: 35},
  {name: 'mel', age: 38}

    sortByOrder: function(stooges, prop, order) {
    if (String(order) === "desc") {
        return _.sortBy(stooges, prop).reverse();
    } else if (String(order) === "asc") {
        return _.sortBy(stooges, prop);
    } else {
        return stooges;

// find elements
var banner = $("#banner-message");
var sort_name_btn = $("button.sort-name");
var sort_age_btn = $("button.sort-age");

function showSortedResults(results, sort_order, prop) {
    banner.append("<p>Sorting: " + prop + ', ' + sort_order + "</p><hr>")
  _.each(results, function(r) {
    banner.append('<li>' + + ' is '+ r.age + ' years old.</li>');

// handle click and add class
sort_name_btn.on("click", function() {
  sort_order = (sort_order === "asc") ? "desc" : "asc"; 
    var sortedResults = _.sortByOrder(stooges, 'name', sort_order);
  showSortedResults(sortedResults, sort_order, 'name');

sort_age_btn.on('click', function() {
    sort_order = (sort_order === "asc") ? "desc" : "asc"; 
    var sortedResults = _.sortByOrder(stooges, 'age', sort_order);
  showSortedResults(sortedResults, sort_order, 'age');

Here's a JSFiddle demonstrating this: JSFiddle for SortBy Mixin

Change the "No file chosen":


  <div class="fileUpload btn btn-primary">
    <label class="upload">
      <input name='Image' type="file"/>
    Upload Image


  display: none;
.fileUpload input.upload 
    display: inline-block;

Note: Btn btn-primary is a class of bootstrap button. However the button may look weired in position. Hope you can fix it by inline css.

Understanding typedefs for function pointers in C

int add(int a, int b)
  return (a+b);
int minus(int a, int b)
  return (a-b);

typedef int (*math_func)(int, int); //declaration of function pointer

int main()
  math_func addition = add;  //typedef assigns a new variable i.e. "addition" to original function "add"
  math_func substract = minus; //typedef assigns a new variable i.e. "substract" to original function "minus"

  int c = addition(11, 11);   //calling function via new variable
  c = substract(11, 5);   //calling function via new variable
  return 0;

Output of this is :



Note that, same math_func definer has been used for the declaring both the function.

Same approach of typedef may be used for extern struct.(using sturuct in other file.)

How to remove files from git staging area?

It is very simple:

  1. To check the current status of any file in the current dir, whether it is staged or not:

    git status

  2. Staging any files:

    git add . for all files in the current directory

    git add <filename> for specific file

  3. Unstaging the file:

    git restore --staged <filename>

Format SQL in SQL Server Management Studio

Azure Data Studio - free and from Microsoft - offers automatic formatting (ctrl + shift + p while editing -> format document). More information about Azure Data Studio here.

While this is not SSMS, it's great for writing queries, free and an official product from Microsoft. It's even cross-platform. Short story: Just switch to Azure Data Studio to write your queries!

Update: Actually Azure Data Studio is in some way the recommended tool for writing queries (source)

Use Azure Data Studio if you: [..] Are mostly editing or executing queries.

How do I enable NuGet Package Restore in Visual Studio?

Package Manager console (Visual Studio, Tools > NuGet Package Manager > Package Manager Console): Run the Update-Package -reinstall -ProjectName command where is the name of the affected project as it appears in Solution Explorer. Use Update-Package -reinstall by itself to restore all packages in the solution. See Update-Package. You can also reinstall a single package, if desired.


How to Disable landscape mode in Android?

Add android:screenOrientation="portrait" to the activity you want to disable landscape mode.

CSS Box Shadow Bottom Only

Do this:

box-shadow: 0 4px 2px -2px gray;

It's actually much simpler, whatever you set the blur to (3rd value), set the spread (4th value) to the negative of it.

JTable - Selected Row click event

You can use the MouseClicked event:

private void tableMouseClicked(java.awt.event.MouseEvent evt) {
 // Do something.

Calling JMX MBean method from a shell script

The following command line JMX utilities are available:

  1. jmxterm - seems to be the most fully featured utility.
  2. cmdline-jmxclient - used in the WebArchive project seems very bare bones (and no development since 2006 it looks like)
  3. Groovy script and JMX - provides some really powerful JMX functionality but requires groovy and other library setup.
  4. JManage command line functionality - (downside is that it requires a running JManage server to proxy commands through)

Groovy JMX Example:

import as JmxFactory
import as JmxUrl

def serverUrl = 'service:jmx:rmi:///jndi/rmi://localhost:9003/jmxrmi'
String beanName = ",id=0"
def server = JmxFactory.connect(new JmxUrl(serverUrl)).MBeanServerConnection
def dataSystem = new GroovyMBean(server, beanName)

println "Connected to:\n$dataSystem\n"

println "Executing jmxForceRefresh()"

cmdline-jmxclient example:

If you have an

  • MBean:,id=0

With an Operation called:

  • jmxForceRefresh()

Then you can write a simple bash script (assuming you download cmdline-jmxclient-0.10.3.jar and put in the same directory as your script):



#No User and password so pass '-'
echo "Available Operations for,id=0"
java -jar ${cmdLineJMXJar} ${user}:${password} ${jmxHost}:${port},id=0

echo "Executing XML update..."
java -jar ${cmdLineJMXJar} - ${jmxHost}:${port},id=0 jmxForceRefresh

How to copy a file to a remote server in Python using SCP or SSH?

Kind of hacky, but the following should work :)

import os
filePath = "/foo/bar/"
serverPath = "/blah/boo/"
os.system("scp "+filePath+" [email protected]:"+serverPath)

Making LaTeX tables smaller? talks about two ways to do this.

I used:


How does functools partial do what it does?

Roughly, partial does something like this (apart from keyword args support etc):

def partial(func, *part_args):
    def wrapper(*extra_args):
        args = list(part_args)
        return func(*args)

    return wrapper

So, by calling partial(sum2, 4) you create a new function (a callable, to be precise) that behaves like sum2, but has one positional argument less. That missing argument is always substituted by 4, so that partial(sum2, 4)(2) == sum2(4, 2)

As for why it's needed, there's a variety of cases. Just for one, suppose you have to pass a function somewhere where it's expected to have 2 arguments:

class EventNotifier(object):
    def __init__(self):
        self._listeners = []

    def add_listener(self, callback):
        ''' callback should accept two positional arguments, event and params '''
        # ...

    def notify(self, event, *params):
        for f in self._listeners:
            f(event, params)

But a function you already have needs access to some third context object to do its job:

def log_event(context, event, params):
    context.log_event("Something happened %s, %s", event, params)

So, there are several solutions:

A custom object:

class Listener(object):
   def __init__(self, context):
       self._context = context

   def __call__(self, event, params):
       self._context.log_event("Something happened %s, %s", event, params)



log_listener = lambda event, params: log_event(context, event, params)

With partials:

context = get_context()  # whatever
notifier.add_listener(partial(log_event, context))

Of those three, partial is the shortest and the fastest. (For a more complex case you might want a custom object though).

shell script. how to extract string using regular expressions

Using bash regular expressions:

if [[ $name =~ $re ]]; then echo ${BASH_REMATCH[1]}; fi

Edit - OP asked for explanation of syntax. Regular expression syntax is a large topic which I can't explain in full here, but I will attempt to explain enough to understand the example.


This is the regular expression stored in a bash variable, re - i.e. what you want your input string to match, and hopefully extract a substring. Breaking it down:

  • http:// is just a string - the input string must contain this substring for the regular expression to match
  • [] Normally square brackets are used say "match any character within the brackets". So c[ao]t would match both "cat" and "cot". The ^ character within the [] modifies this to say "match any character except those within the square brackets. So in this case [^/] will match any character apart from "/".
  • The square bracket expression will only match one character. Adding a + to the end of it says "match 1 or more of the preceding sub-expression". So [^/]+ matches 1 or more of the set of all characters, excluding "/".
  • Putting () parentheses around a subexpression says that you want to save whatever matched that subexpression for later processing. If the language you are using supports this, it will provide some mechanism to retrieve these submatches. For bash, it is the BASH_REMATCH array.
  • Finally we do an exact match on "/" to make sure we match all the way to end of the fully qualified domain name and the following "/"

Next, we have to test the input string against the regular expression to see if it matches. We can use a bash conditional to do that:

if [[ $name =~ $re ]]; then
    echo ${BASH_REMATCH[1]}

In bash, the [[ ]] specify an extended conditional test, and may contain the =~ bash regular expression operator. In this case we test whether the input string $name matches the regular expression $re. If it does match, then due to the construction of the regular expression, we are guaranteed that we will have a submatch (from the parentheses ()), and we can access it using the BASH_REMATCH array:

  • Element 0 of this array ${BASH_REMATCH[0]} will be the entire string matched by the regular expression, i.e. "".
  • Subsequent elements of this array will be subsequent results of submatches. Note you can have multiple submatch () within a regular expression - The BASH_REMATCH elements will correspond to these in order. So in this case ${BASH_REMATCH[1]} will contain "", which I think is the string you want.

Note that the contents of the BASH_REMATCH array only apply to the last time the regular expression =~ operator was used. So if you go on to do more regular expression matches, you must save the contents you need from this array each time.

This may seem like a lengthy description, but I have really glossed over several of the intricacies of regular expressions. They can be quite powerful, and I believe with decent performance, but the regular expression syntax is complex. Also regular expression implementations vary, so different languages will support different features and may have subtle differences in syntax. In particular escaping of characters within a regular expression can be a thorny issue, especially when those characters would have an otherwise different meaning in the given language.

Note that instead of setting the $re variable on a separate line and referring to this variable in the condition, you can put the regular expression directly into the condition. However in bash 3.2, the rules were changed regarding whether quotes around such literal regular expressions are required or not. Putting the regular expression in a separate variable is a straightforward way around this, so that the condition works as expected in all bash versions that support the =~ match operator.

How can I change the font size using seaborn FacetGrid?

You can scale up the fonts in your call to sns.set().

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
x = np.random.normal(size=37)
y = np.random.lognormal(size=37)

# defaults
fig, ax = plt.subplots()
ax.plot(x, y, marker='s', linestyle='none', label='small')
ax.legend(loc='upper left', bbox_to_anchor=(0, 1.1))

enter image description here

sns.set(font_scale=5)  # crazy big
fig, ax = plt.subplots()
ax.plot(x, y, marker='s', linestyle='none', label='big')
ax.legend(loc='upper left', bbox_to_anchor=(0, 1.3))

enter image description here

Colorplot of 2D array matplotlib

I'm afraid your posted example is not working, since X and Y aren't defined. So instead of pcolormesh let's use imshow:

import numpy as np
import matplotlib.pyplot as plt

H = np.array([[1, 2, 3, 4],
              [5, 6, 7, 8],
              [9, 10, 11, 12],
              [13, 14, 15, 16]])  # added some commas and array creation code

fig = plt.figure(figsize=(6, 3.2))

ax = fig.add_subplot(111)

cax = fig.add_axes([0.12, 0.1, 0.78, 0.8])

Android - implementing startForeground for a service?

In addition to RAWA answer, this peace of code:

} else {

You can change to:

ContextCompat.startForegroundService(context, yourIntent);

If you will look inside this method then you can see that this method do all checking work for you.