Programs & Examples On #Isnullorempty

Difference between IsNullOrEmpty and IsNullOrWhiteSpace in C#

[Performance Test] just in case anyone is wondering, in a stopwatch test comparing

if(nopass.Trim().Length > 0)

if (!string.IsNullOrWhiteSpace(nopass))



these were the results:

Trim-Length with empty value = 15

Trim-Length with not empty value = 52


IsNullOrWhiteSpace with empty value = 11

IsNullOrWhiteSpace with not empty value = 12

Check if list is empty in C#

What about using the Count property.

 if(listOfObjects.Count != 0)
 {
     ShowGrid();
     HideError();
 }
 else
 {
     HideGrid();
     ShowError();
 }

One liner for If string is not null or empty else

You could use the ternary operator:

return string.IsNullOrEmpty(strTestString) ? "0" : strTestString

FooTextBox.Text = string.IsNullOrEmpty(strFoo) ? "0" : strFoo;

SQLite select where empty?

You can do this with the following:

int counter = 0;
String sql = "SELECT projectName,Owner " + "FROM Project WHERE Owner= ?";
PreparedStatement prep = conn.prepareStatement(sql);
prep.setString(1, "");
ResultSet rs = prep.executeQuery();
while (rs.next()) {
    counter++;
}
System.out.println(counter);

This will give you the no of rows where the column value is null or blank.

How to print spaces in Python?

this is how to print whitespaces in python.

import string  
string.whitespace  
'\t\n\x0b\x0c\r '   
i.e .   
print "hello world"   
print "Hello%sworld"%' '   
print "hello", "world"   
print "Hello "+"world   

How to create a .gitignore file

========== In Windows ==========

  1. Open Notepad.
  2. Add the contents of your gitignore file.
  3. Click "Save as" and select "all files".
  4. Save as .gitignore.

======== Easy peasy! No command line required! ========

Android SeekBar setOnSeekBarChangeListener

All answers are correct, but you need to convert a long big fat number into a timer first:

    public String toTimer(long milliseconds){
    String finalTimerString = "";
    String secondsString;
    // Convert total duration into time
    int hours = (int)( milliseconds / (1000*60*60));
    int minutes = (int)(milliseconds % (1000*60*60)) / (1000*60);
    int seconds = (int) ((milliseconds % (1000*60*60)) % (1000*60) / 1000);
    // Add hours if there
    if(hours > 0){
        finalTimerString = hours + ":";
    }
    // Prepending 0 to seconds if it is one digit
    if(seconds < 10){
        secondsString = "0" + seconds;
    }else{
        secondsString = "" + seconds;}
    finalTimerString = finalTimerString + minutes + ":" + secondsString;
    // return timer string
    return finalTimerString;
}

And this is how you use it:

@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
textView.setText(String.format("%s", toTimer(progress)));        
}

How to get date representing the first day of a month?

SELECT DATEADD(day,1-DATEpart(day, GETDATE()),GETDATE())

How can I search Git branches for a file or directory?

You could use gitk --all and search for commits "touching paths" and the pathname you are interested in.

Convert audio files to mp3 using ffmpeg

If you have a folder and sub-folder full of wav's you want to convert, put below command in a file, save it in a .bat file in the root of the folder where you wan to convert, and then run the bat file

for /R %%g in (*.wav) do start /b /wait "" "C:\ffmpeg-4.0.1-win64-static\bin\ffmpeg" -threads 16 -i "%%g" -acodec libmp3lame "%%~dpng.mp3" && del "%%g"

jQuery Event : Detect changes to the html/text of a div

Adding some content to a div, whether through jQuery or via de DOM-API directly, defaults to the .appendChild() function. What you can do is to override the .appendChild() function of the current object and implement an observer in it. Now having overridden our .appendChild() function, we need to borrow that function from an other object to be able to append the content. Therefor we call the .appendChild() of an other div to finally append the content. Ofcourse, this counts also for the .removeChild().

var obj = document.getElementById("mydiv");
    obj.appendChild = function(node) {
        alert("changed!");

        // call the .appendChild() function of some other div
        // and pass the current (this) to let the function affect it.
        document.createElement("div").appendChild.call(this, node);
        }
    };

Here you can find a naïf example. You can extend it by yourself I guess. http://jsfiddle.net/RKLmA/31/

By the way: this shows JavaScript complies the OpenClosed priciple. :)

How to list containers in Docker

List running containers:-

$ docker ps

List all containers:-

$ docker ps -a

List only stopped containers:-

$ docker ps --filter "status=exited"

or

$ docker ps -f "status=exited"

phpmyadmin.pma_table_uiprefs doesn't exist

Try sudo dpkg-reconfigure phpmyadmin

To Replace config file /etc/phpmyadmin/config-db.php with new version

What are some examples of commonly used practices for naming git branches?

I've mixed and matched from different schemes I've seen and based on the tooling I'm using.
So my completed branch name would be:

name/feature/issue-tracker-number/short-description

which would translate to:

mike/blogs/RSSI-12/logo-fix

The parts are separated by forward slashes because those get interpreted as folders in SourceTree for easy organization. We use Jira for our issue tracking so including the number makes it easier to look up in the system. Including that number also makes it searchable when trying to find that issue inside Github when trying to submit a pull request.

What is the difference between a field and a property?

Properties have the primary advantage of allowing you to change the way data on an object is accessed without breaking it's public interface. For example, if you need to add extra validation, or to change a stored field into a calculated you can do so easily if you initially exposed the field as a property. If you just exposed a field directly, then you would have to change the public interface of your class to add the new functionality. That change would break existing clients, requiring them to be recompiled before they could use the new version of your code.

If you write a class library designed for wide consumption (like the .NET Framework, which is used by millions of people), that can be a problem. However, if you are writing a class used internally inside a small code base (say <= 50 K lines), it's really not a big deal, because no one would be adversely affected by your changes. In that case it really just comes down to personal preference.

Display Image On Text Link Hover CSS Only

I did something like that:

HTML:

<p class='parent'>text text text</p>
<img class='child' src='idk.png'>

CSS:

.child {
    visibility: hidden;
}

.parent:hover .child {
    visibility: visible;
}

Drag and drop a DLL to the GAC ("assembly") in windows server 2008 .net 4.0

Other alternatives to an installer and gacutil are GUI tools like Gac Manager or GACAdmin. Or if you like PowerShell you could use PowerShell GAC from which I am the author.

How to list all files in a directory and its subdirectories in hadoop hdfs

Code snippet for both recursive and non-recursive approaches:

//helper method to get the list of files from the HDFS path
public static List<String>
    listFilesFromHDFSPath(Configuration hadoopConfiguration,
                          String hdfsPath,
                          boolean recursive) throws IOException,
                                        IllegalArgumentException
{
    //resulting list of files
    List<String> filePaths = new ArrayList<String>();

    //get path from string and then the filesystem
    Path path = new Path(hdfsPath);  //throws IllegalArgumentException
    FileSystem fs = path.getFileSystem(hadoopConfiguration);

    //if recursive approach is requested
    if(recursive)
    {
        //(heap issues with recursive approach) => using a queue
        Queue<Path> fileQueue = new LinkedList<Path>();

        //add the obtained path to the queue
        fileQueue.add(path);

        //while the fileQueue is not empty
        while (!fileQueue.isEmpty())
        {
            //get the file path from queue
            Path filePath = fileQueue.remove();

            //filePath refers to a file
            if (fs.isFile(filePath))
            {
                filePaths.add(filePath.toString());
            }
            else   //else filePath refers to a directory
            {
                //list paths in the directory and add to the queue
                FileStatus[] fileStatuses = fs.listStatus(filePath);
                for (FileStatus fileStatus : fileStatuses)
                {
                    fileQueue.add(fileStatus.getPath());
                } // for
            } // else

        } // while

    } // if
    else        //non-recursive approach => no heap overhead
    {
        //if the given hdfsPath is actually directory
        if(fs.isDirectory(path))
        {
            FileStatus[] fileStatuses = fs.listStatus(path);

            //loop all file statuses
            for(FileStatus fileStatus : fileStatuses)
            {
                //if the given status is a file, then update the resulting list
                if(fileStatus.isFile())
                    filePaths.add(fileStatus.getPath().toString());
            } // for
        } // if
        else        //it is a file then
        {
            //return the one and only file path to the resulting list
            filePaths.add(path.toString());
        } // else

    } // else

    //close filesystem; no more operations
    fs.close();

    //return the resulting list
    return filePaths;
} // listFilesFromHDFSPath

Getting key with maximum value in dictionary?

For scientific python users, here is a simple solution using Pandas:

import pandas as pd
stats = {'a': 1000, 'b': 3000, 'c': 100}
series = pd.Series(stats)
series.idxmax()

>>> b

Assert that a method was called in a Python unit test

Yes, I can give you the outline but my Python is a bit rusty and I'm too busy to explain in detail.

Basically, you need to put a proxy in the method that will call the original, eg:

 class fred(object):
   def blog(self):
     print "We Blog"


 class methCallLogger(object):
   def __init__(self, meth):
     self.meth = meth

   def __call__(self, code=None):
     self.meth()
     # would also log the fact that it invoked the method

 #example
 f = fred()
 f.blog = methCallLogger(f.blog)

This StackOverflow answer about callable may help you understand the above.

In more detail:

Although the answer was accepted, due to the interesting discussion with Glenn and having a few minutes free, I wanted to enlarge on my answer:

# helper class defined elsewhere
class methCallLogger(object):
   def __init__(self, meth):
     self.meth = meth
     self.was_called = False

   def __call__(self, code=None):
     self.meth()
     self.was_called = True

#example
class fred(object):
   def blog(self):
     print "We Blog"

f = fred()
g = fred()
f.blog = methCallLogger(f.blog)
g.blog = methCallLogger(g.blog)
f.blog()
assert(f.blog.was_called)
assert(not g.blog.was_called)

How to alert using jQuery

For each works with JQuery as in

$(<selector>).each(function() {
   //this points to item
   alert('<msg>');
});

JQuery also, for a popup, has in the UI library a dialog widget: http://jqueryui.com/demos/dialog/

Check it out, works really well.

HTH.

Can I use break to exit multiple nested 'for' loops?

The break statement terminates the execution of the nearest enclosing do, for, switch, or while statement in which it appears. Control passes to the statement that follows the terminated statement.

from msdn.

How to use matplotlib tight layout with Figure?

Just call fig.tight_layout() as you normally would. (pyplot is just a convenience wrapper. In most cases, you only use it to quickly generate figure and axes objects and then call their methods directly.)

There shouldn't be a difference between the QtAgg backend and the default backend (or if there is, it's a bug).

E.g.

import matplotlib.pyplot as plt

#-- In your case, you'd do something more like:
# from matplotlib.figure import Figure
# fig = Figure()
#-- ...but we want to use it interactive for a quick example, so 
#--    we'll do it this way
fig, axes = plt.subplots(nrows=4, ncols=4)

for i, ax in enumerate(axes.flat, start=1):
    ax.set_title('Test Axes {}'.format(i))
    ax.set_xlabel('X axis')
    ax.set_ylabel('Y axis')

plt.show()

Before Tight Layout

enter image description here

After Tight Layout

import matplotlib.pyplot as plt

fig, axes = plt.subplots(nrows=4, ncols=4)

for i, ax in enumerate(axes.flat, start=1):
    ax.set_title('Test Axes {}'.format(i))
    ax.set_xlabel('X axis')
    ax.set_ylabel('Y axis')

fig.tight_layout()

plt.show()

enter image description here

Is Secure.ANDROID_ID unique for each device?

I've read a few things about this and unfortunately the ANDROID_ID should not be relied on for uniquely identifying an individual device.

It doesn't seem to be enforced in Android compliance requirements and so manufacturers seem to implement it the way they choose including some using it more as a 'model' ID etc.

Also, be aware that even if a manufacturer has written a generator to make it a UUID (for example), it's not guaranteed to survive a factory reset.

CardView background color always white

You can use

app:cardBackgroundColor="@color/red"

or

android:backgroundTint="@color/red"

Android Image View Pinch Zooming

Add bellow line in build.gradle:

compile 'com.commit451:PhotoView:1.2.4'

or

compile 'com.github.chrisbanes:PhotoView:1.3.0'

In Java file:

PhotoViewAttacher photoAttacher;
photoAttacher= new PhotoViewAttacher(Your_Image_View);
photoAttacher.update();

Getting 404 Not Found error while trying to use ErrorDocument

When we apply local url, ErrorDocument directive expect the full path from DocumentRoot. There fore,

 ErrorDocument 404 /yourfoldernames/errors/404.html

How to insert a data table into SQL Server database table?

Create a User-Defined TableType in your database:

CREATE TYPE [dbo].[MyTableType] AS TABLE(
    [Id] int NOT NULL,
    [Name] [nvarchar](128) NULL
)

and define a parameter in your Stored Procedure:

CREATE PROCEDURE [dbo].[InsertTable]
    @myTableType MyTableType readonly
AS
BEGIN
    insert into [dbo].Records select * from @myTableType 
END

and send your DataTable directly to sql server:

using (var command = new SqlCommand("InsertTable") {CommandType = CommandType.StoredProcedure})
{
    var dt = new DataTable(); //create your own data table
    command.Parameters.Add(new SqlParameter("@myTableType", dt));
    SqlHelper.Exec(command);
}

To edit the values inside stored-procedure, you can declare a local variable with the same type and insert input table into it:

DECLARE @modifiableTableType MyTableType 
INSERT INTO @modifiableTableType SELECT * FROM @myTableType

Then, you can edit @modifiableTableType:

UPDATE @modifiableTableType SET [Name] = 'new value'

How to read json file into java with simple JSON library

Reading from JsonFile

public static ArrayList<Employee> readFromJsonFile(String fileName){
        ArrayList<Employee> result = new ArrayList<Employee>();

        try{
            String text = new String(Files.readAllBytes(Paths.get(fileName)), StandardCharsets.UTF_8);

            JSONObject obj = new JSONObject(text);
            JSONArray arr = obj.getJSONArray("employees");

            for(int i = 0; i < arr.length(); i++){
                String name = arr.getJSONObject(i).getString("name");
                short salary = Short.parseShort(arr.getJSONObject(i).getString("salary"));
                String position = arr.getJSONObject(i).getString("position");
                byte years_in_company = Byte.parseByte(arr.getJSONObject(i).getString("years_in_company")); 
                if (position.compareToIgnoreCase("manager") == 0){
                    result.add(new Manager(name, salary, position, years_in_company));
                }
                else{
                    result.add(new OrdinaryEmployee(name, salary, position, years_in_company));
                }
            }           
        }
        catch(Exception ex){
            System.out.println(ex.toString());
        }
        return result;
    }

How to catch and print the full exception traceback without halting/exiting the program?

To get the precise stack trace, as a string, that would have been raised if no try/except were there to step over it, simply place this in the except block that catches the offending exception.

desired_trace = traceback.format_exc(sys.exc_info())

Here's how to use it (assuming flaky_func is defined, and log calls your favorite logging system):

import traceback
import sys

try:
    flaky_func()
except KeyboardInterrupt:
    raise
except Exception:
    desired_trace = traceback.format_exc(sys.exc_info())
    log(desired_trace)

It's a good idea to catch and re-raise KeyboardInterrupts, so that you can still kill the program using Ctrl-C. Logging is outside the scope of the question, but a good option is logging. Documentation for the sys and traceback modules.

How does String substring work in Swift

Swift 4 & 5:

extension String {
  subscript(_ i: Int) -> String {
    let idx1 = index(startIndex, offsetBy: i)
    let idx2 = index(idx1, offsetBy: 1)
    return String(self[idx1..<idx2])
  }

  subscript (r: Range<Int>) -> String {
    let start = index(startIndex, offsetBy: r.lowerBound)
    let end = index(startIndex, offsetBy: r.upperBound)
    return String(self[start ..< end])
  }

  subscript (r: CountableClosedRange<Int>) -> String {
    let startIndex =  self.index(self.startIndex, offsetBy: r.lowerBound)
    let endIndex = self.index(startIndex, offsetBy: r.upperBound - r.lowerBound)
    return String(self[startIndex...endIndex])
  }
}

How to use it:

"abcde"[0] --> "a"

"abcde"[0...2] --> "abc"

"abcde"[2..<4] --> "cd"

Can't find file executable in your configured search path for gnc gcc compiler

* How to Download and install CodeBlocks.* ( I have already downloaded )


***How to solve the CodeBlocks environment error.

  1. Go to "Settings"----"Compiler"----"Selected compiler"( GNU GCC Compiler ).

  2. Then, Selected "Toolchain executables".

  3. Now, "( C:\Program Files (x86)\CodeBlocks\MinGW )"

See Video : https://youtu.be/Tb1VnXs60Lg

What is log4j's default log file dumping path

By default, Log4j logs to standard output and that means you should be able to see log messages on your Eclipse's console view. To log to a file you need to use a FileAppender explicitly by defining it in a log4j.properties file in your classpath.

Create the following log4j.properties file in your classpath. This allows you to log your message to both a file as well as your console.

log4j.rootLogger=debug, stdout, file

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=example.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%p %t %c - %m%n

Note: The above creates an example.log in your current working directory (i.e. Eclipse's project directory) so that the same log4j.properties could work with different projects without overwriting each other's logs.

References:
Apache log4j 1.2 - Short introduction to log4j

The type or namespace name 'DbContext' could not be found

Just a quick note. It is DbContext, not DBContext. i.e. with a lowercase 'B'. I discovered this because I had the same problem while intelesense was not working until I tried typing the full name space System.Data.Entity... and name and finally it suggested the lowercase 'b' option:-

System.Data.Entity.DbContext

sudo: docker-compose: command not found

On Ubuntu 16.04

Here's how I fixed this issue: Refer Docker Compose documentation

  1. sudo curl -L https://github.com/docker/compose/releases/download/1.21.0/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose

  2. sudo chmod +x /usr/local/bin/docker-compose

After you do the curl command , it'll put docker-compose into the

/usr/local/bin

which is not on the PATH. To fix it, create a symbolic link:

  1. sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose

And now if you do: docker-compose --version

You'll see that docker-compose is now on the PATH

Remove characters from a String in Java

Strings are immutable. Therefore String.replace() does not modify id, it returns a new String with the appropriate value. Therefore you want to use id = id.replace(".xml", "");.

How to set up a Web API controller for multipart/form-data

You can use something like this

[HttpPost]
public async Task<HttpResponseMessage> AddFile()
{
    if (!Request.Content.IsMimeMultipartContent())
    {
        this.Request.CreateResponse(HttpStatusCode.UnsupportedMediaType);
    }

    string root = HttpContext.Current.Server.MapPath("~/temp/uploads");
    var provider = new MultipartFormDataStreamProvider(root);
    var result = await Request.Content.ReadAsMultipartAsync(provider);

    foreach (var key in provider.FormData.AllKeys)
    {
        foreach (var val in provider.FormData.GetValues(key))
        {
            if (key == "companyName")
            {
                var companyName = val;
            }
        }
    }

    // On upload, files are given a generic name like "BodyPart_26d6abe1-3ae1-416a-9429-b35f15e6e5d5"
    // so this is how you can get the original file name
    var originalFileName = GetDeserializedFileName(result.FileData.First());

    var uploadedFileInfo = new FileInfo(result.FileData.First().LocalFileName);
    string path = result.FileData.First().LocalFileName;

    //Do whatever you want to do with your file here

    return this.Request.CreateResponse(HttpStatusCode.OK, originalFileName );
}

private string GetDeserializedFileName(MultipartFileData fileData)
{
    var fileName = GetFileName(fileData);
    return JsonConvert.DeserializeObject(fileName).ToString();
}

public string GetFileName(MultipartFileData fileData)
{
    return fileData.Headers.ContentDisposition.FileName;
}

Scroll / Jump to id without jQuery

Oxi's answer is just wrong.¹

What you want is:

var container = document.body,
element = document.getElementById('ElementID');
container.scrollTop = element.offsetTop;

Working example:

(function (){
  var i = 20, l = 20, html = '';
  while (i--){
    html += '<div id="DIV' +(l-i)+ '">DIV ' +(l-i)+ '</div>';
    html += '<a onclick="document.body.scrollTop=document.getElementById(\'DIV' +i+ '\').offsetTop">';
    html += '[ Scroll to #DIV' +i+ ' ]</a>';
    html += '<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br />';
  }
  document.write( html );
})();

¹ I haven't got enough reputation to comment on his answer

How to AUTO_INCREMENT in db2?

You will have to create an auto-increment field with the sequence object (this object generates a number sequence).

Use the following CREATE SEQUENCE syntax:

  CREATE SEQUENCE seq_person
  MINVALUE 1
  START WITH 1
  INCREMENT BY 1
  CACHE 10

The code above creates a sequence object called seq_person, that starts with 1 and will increment by 1. It will also cache up to 10 values for performance. The cache option specifies how many sequence values will be stored in memory for faster access.

To insert a new record into the "Persons" table, we will have to use the nextval function (this function retrieves the next value from seq_person sequence):

  INSERT INTO Persons (P_Id,FirstName,LastName)
  VALUES (seq_person.nextval,'Lars','Monsen')

The SQL statement above would insert a new record into the "Persons" table. The "P_Id" column would be assigned the next number from the seq_person sequence. The "FirstName" column would be set to "Lars" and the "LastName" column would be set to "Monsen".

Uninstall / remove a Homebrew package including all its dependencies

EDIT:

It looks like the issue is now solved using an external command called brew rmdeps or brew rmtree.

To install and use, issue the following commands:

$ brew tap beeftornado/rmtree
$ brew rmtree <package>

See the above link for more information and discussion.


Original answer:

It appears that currently, there's no easy way to accomplish this.

However, I filed an issue on Homebrew's GitHub page, and somebody suggested a temporary solution until they add an exclusive command to solve this.

There's an external command called brew leaves which prints all packages that are not dependencies of other packages.

If you do a logical and on the output of brew leaves and brew deps <package>, you might just get a list of the orphaned dependency packages, which you can uninstall manually afterwards. Combine this with xargs and you'll get what you need, I guess (untested, don't count on this).


EDIT: Somebody just suggested a very similar solution, using join instead of xargs:

brew rm FORMULA
brew rm $(join <(brew leaves) <(brew deps FORMULA))

See the comment on the issue mentioned above for more info.

How to get the current logged in user Id in ASP.NET Core

Make sure that you have enable windows authentication. If you have anonymous authentication enabled you may be getting a null string.

https://docs.microsoft.com/en-us/aspnet/core/security/authentication/windowsauth?view=aspnetcore-3.1&tabs=visual-studio

Elegant way to create empty pandas DataFrame with NaN of type float

You could specify the dtype directly when constructing the DataFrame:

>>> df = pd.DataFrame(index=range(0,4),columns=['A'], dtype='float')
>>> df.dtypes
A    float64
dtype: object

Specifying the dtype forces Pandas to try creating the DataFrame with that type, rather than trying to infer it.

How to find the kafka version in linux

Simple way on macOS e.g. installed via homebrew

$ ls -l $(which kafka-topics)
/usr/local/bin/kafka-topics -> ../Cellar/kafka/0.11.0.1/bin/kafka-topics

How to use custom font in a project written in Android Studio

https://i.stack.imgur.com/i6XNU.png

  1. Select File>New>Folder>Assets Folder

  2. Click finish

  3. Right click on assets and create a folder called fonts

  4. Put your font file in assets > fonts

  5. Use code below to change your textView's font

    TextView textView = (TextView) findViewById(R.id.textView);
    Typeface typeface = Typeface.createFromAsset(getAssets(), "fonts/yourfont.ttf");
    textView.setTypeface(typeface);
    

Convert Month Number to Month Name Function in SQL

in addition to original

SELECT DATENAME(m, str(2) + '/1/2011')

you can do this

SELECT DATENAME(m, str([column_name]) + '/1/2011')

this way you get names for all rows in a table. where [column_name] represents a integer column containing numeric value 1 through 12

2 represents any integer, by contact string i created a date where i can extract the month. '/1/2011' can be any date

if you want to do this with variable

DECLARE @integer int;

SET @integer = 6;

SELECT DATENAME(m, str(@integer) + '/1/2011')

Property 'catch' does not exist on type 'Observable<any>'

Warning: This solution is deprecated since Angular 5.5, please refer to Trent's answer below

=====================

Yes, you need to import the operator:

import 'rxjs/add/operator/catch';

Or import Observable this way:

import {Observable} from 'rxjs/Rx';

But in this case, you import all operators.

See this question for more details:

Xcode Product -> Archive disabled

You've changed your scheme destination to a simulator instead of Generic iOS Device.

That's why it is greyed out.

Change from a simulator to Generic iOS Device

Update value of a nested dictionary of varying depth

Just use python-benedict (I did it), it has a merge (deepupdate) utility method and many others. It works with python 2 / python 3 and it is well tested.

from benedict import benedict

dictionary1=benedict({'level1':{'level2':{'levelA':0,'levelB':1}}})
update={'level1':{'level2':{'levelB':10}}}
dictionary1.merge(update)
print(dictionary1)
# >> {'level1':{'level2':{'levelA':0,'levelB':10}}}

Installation: pip install python-benedict

Documentation: https://github.com/fabiocaccamo/python-benedict

Note: I am the author of this project

How to match "any character" in regular expression?

Yes that will work, though note that . will not match newlines unless you pass the DOTALL flag when compiling the expression:

Pattern pattern = Pattern.compile(".*123", Pattern.DOTALL);
Matcher matcher = pattern.matcher(inputStr);
boolean matchFound = matcher.matches();

Append lines to a file using a StreamWriter

Replace this:

StreamWriter file2 = new StreamWriter("c:/file.txt");

with this:

StreamWriter file2 = new StreamWriter("c:/file.txt", true);

true indicates that it appends text.

How to assign from a function which returns more than one value?

To obtain multiple outputs from a function and keep them in the desired format you can save the outputs to your hard disk (in the working directory) from within the function and then load them from outside the function:

myfun <- function(x) {
                      df1 <- ...
                      df2 <- ...
                      save(df1, file = "myfile1")
                      save(df2, file = "myfile2")
}
load("myfile1")
load("myfile2")

Setting up PostgreSQL ODBC on Windows

Please note that you must install the driver for the version of your software client(MS access) not the version of the OS. that's mean that if your MS Access is a 32-bits version,you must install a 32-bit odbc driver. regards

List of foreign keys and the tables they reference in Oracle DB

In case one wants to create FK constraints from UAT environment table to Live, fire below dynamic query.....

    SELECT 'ALTER TABLE '||OBJ.NAME||' ADD CONSTRAINT '||CONST.NAME||'     FOREIGN KEY ('||COALESCE(ACOL.NAME, COL.NAME)||') REFERENCES '
||ROBJ.NAME ||' ('||COALESCE(RACOL.NAME, RCOL.NAME) ||');'
FROM SYS.CON$ CONST
INNER JOIN SYS.CDEF$ CDEF ON CDEF.CON# = CONST.CON#
INNER JOIN SYS.CCOL$ CCOL ON CCOL.CON# = CONST.CON#
INNER JOIN SYS.COL$ COL  ON (CCOL.OBJ# = COL.OBJ#) AND (CCOL.INTCOL# =     COL.INTCOL#)
INNER JOIN SYS.OBJ$ OBJ ON CCOL.OBJ# = OBJ.OBJ#
LEFT JOIN SYS.ATTRCOL$ ACOL ON (CCOL.OBJ# = ACOL.OBJ#) AND (CCOL.INTCOL# =     ACOL.INTCOL#)

INNER JOIN SYS.CON$ RCONST ON RCONST.CON# = CDEF.RCON#
INNER JOIN SYS.CCOL$ RCCOL ON RCCOL.CON# = RCONST.CON#
INNER JOIN SYS.COL$ RCOL  ON (RCCOL.OBJ# = RCOL.OBJ#) AND (RCCOL.INTCOL# =     RCOL.INTCOL#)
INNER JOIN SYS.OBJ$ ROBJ ON RCCOL.OBJ# = ROBJ.OBJ#
LEFT JOIN SYS.ATTRCOL$ RACOL  ON (RCCOL.OBJ# = RACOL.OBJ#) AND     (RCCOL.INTCOL# = RACOL.INTCOL#)

WHERE CONST.OWNER# = userenv('SCHEMAID')
AND RCONST.OWNER# = userenv('SCHEMAID')
AND CDEF.TYPE# = 4 
AND OBJ.NAME = <table_name>;

How to set JAVA_HOME in Linux for all users

  1. find /usr/lib/jvm/java-1.x.x-openjdk
  2. vim /etc/profile

    Prepend sudo if logged in as not-privileged user, ie. sudo vim

  3. Press 'i' to get in insert mode
  4. add:

    export JAVA_HOME="path that you found"
    
    export PATH=$JAVA_HOME/bin:$PATH
    
  5. logout and login again, reboot, or use source /etc/profile to apply changes immediately in your current shell

Resize to fit image in div, and center horizontally and vertically

This is one way to do it:

Fiddle here: http://jsfiddle.net/4Mvan/1/

HTML:

<div class='container'>
    <a href='#'>
    <img class='resize_fit_center'
      src='http://i.imgur.com/H9lpVkZ.jpg' />
    </a>
</div>

CSS:

.container {
    margin: 10px;
    width: 115px;
    height: 115px;
    line-height: 115px;
    text-align: center;
    border: 1px solid red;
}
.resize_fit_center {
    max-width:100%;
    max-height:100%;
    vertical-align: middle;
}

Is there any boolean type in Oracle databases?

Not only is the boolean datatype missing in Oracle's SQL (not PL/SQL), but they also have no clear recommendation about what to use instead. See this thread on asktom. From recommending CHAR(1) 'Y'/'N' they switch to NUMBER(1) 0/1 when someone points out that 'Y'/'N' depends on the English language, while e.g. German programmers might use 'J'/'N' instead.

The worst thing is that they defend this stupid decision just like they defend the ''=NULL stupidity.

In-memory size of a Python structure

These answers all collect shallow size information. I suspect that visitors to this question will end up here looking to answer the question, "How big is this complex object in memory?"

There's a great answer here: https://goshippo.com/blog/measure-real-size-any-python-object/

The punchline:

import sys

def get_size(obj, seen=None):
    """Recursively finds size of objects"""
    size = sys.getsizeof(obj)
    if seen is None:
        seen = set()
    obj_id = id(obj)
    if obj_id in seen:
        return 0
    # Important mark as seen *before* entering recursion to gracefully handle
    # self-referential objects
    seen.add(obj_id)
    if isinstance(obj, dict):
        size += sum([get_size(v, seen) for v in obj.values()])
        size += sum([get_size(k, seen) for k in obj.keys()])
    elif hasattr(obj, '__dict__'):
        size += get_size(obj.__dict__, seen)
    elif hasattr(obj, '__iter__') and not isinstance(obj, (str, bytes, bytearray)):
        size += sum([get_size(i, seen) for i in obj])
    return size

Used like so:

In [1]: get_size(1)
Out[1]: 24

In [2]: get_size([1])
Out[2]: 104

In [3]: get_size([[1]])
Out[3]: 184

If you want to know Python's memory model more deeply, there's a great article here that has a similar "total size" snippet of code as part of a longer explanation: https://code.tutsplus.com/tutorials/understand-how-much-memory-your-python-objects-use--cms-25609

How to read a file in Groovy into a string?

the easiest way would be

new File(filename).getText()

which means you could just do:

new File(filename).text

Remove a modified file from pull request

Switch to the branch from which you created the pull request:

$ git checkout pull-request-branch

Overwrite the modified file(s) with the file in another branch, let's consider it's master:

git checkout origin/master -- src/main/java/HelloWorld.java

Commit and push it to the remote:

git commit -m "Removed a modified file from pull request"
git push origin pull-request-branch

How to commit my current changes to a different branch in Git

The other answers suggesting checking out the other branch, then committing to it, only work if the checkout is possible given the local modifications. If not, you're in the most common use case for git stash:

git stash
git checkout other-branch
git stash pop

The first stash hides away your changes (basically making a temporary commit), and the subsequent stash pop re-applies them. This lets Git use its merge capabilities.

If, when you try to pop the stash, you run into merge conflicts... the next steps depend on what those conflicts are. If all the stashed changes indeed belong on that other branch, you're simply going to have to sort through them - it's a consequence of having made your changes on the wrong branch.

On the other hand, if you've really messed up, and your work tree has a mix of changes for the two branches, and the conflicts are just in the ones you want to commit back on the original branch, you can save some work. As usual, there are a lot of ways to do this. Here's one, starting from after you pop and see the conflicts:

# Unstage everything (warning: this leaves files with conflicts in your tree)
git reset

# Add the things you *do* want to commit here
git add -p     # or maybe git add -i
git commit

# The stash still exists; pop only throws it away if it applied cleanly
git checkout original-branch
git stash pop

# Add the changes meant for this branch
git add -p
git commit

# And throw away the rest
git reset --hard

Alternatively, if you realize ahead of the time that this is going to happen, simply commit the things that belong on the current branch. You can always come back and amend that commit:

git add -p
git commit
git stash
git checkout other-branch
git stash pop

And of course, remember that this all took a bit of work, and avoid it next time, perhaps by putting your current branch name in your prompt by adding $(__git_ps1) to your PS1 environment variable in your bashrc file. (See for example the Git in Bash documentation.)

create a text file using javascript

From a web page this cannot work since IE restricts the use of that object.

Getting checkbox values on submit

(It's not action="get" or action="post" it's method="get" or method="post"

Try to do it using post method:

<form action="third.php" method="POST">
    Red<input type="checkbox" name="color[]" id="color" value="red">
    Green<input type="checkbox" name="color[]" id="color" value="green">
    Blue<input type="checkbox" name="color[]" id="color" value="blue">
    Cyan<input type="checkbox" name="color[]" id="color" value="cyan">
    Magenta<input type="checkbox" name="color[]" id="color" value="Magenta">
    Yellow<input type="checkbox" name="color[]" id="color" value="yellow">
    Black<input type="checkbox" name="color[]" id="color" value="black">
    <input type="submit" value="submit">
</form>

and in third.php

or for a pericular field you colud get value in:

$_POST['color'][0] //for RED
$_POST['color'][1] // for GREEN

Cursor adapter and sqlite example

In Android, How to use a Cursor with a raw query in sqlite:

Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM mytable " +
           "where Age > 10 LIMIT 5", null);

if (c != null ) {
    if  (c.moveToFirst()) {
        do {
            String firstName = c.getString(c.getColumnIndex("FirstName"));
            int age = c.getInt(c.getColumnIndex("Age"));
            results.add("" + firstName + ",Age: " + age);
        }while (c.moveToNext());
    }
}
c.close();

Android Studio don't generate R.java for my import project

In my case I had an empty line prior a drawable definition in xml. This was braking aapt essentially not allowing to generate R.java .

Showing which files have changed between two revisions

There are two branches lets say

  • A (Branch on which you are working)
  • B (Another branch with which you want to compare)

Being in branch A you can type

git diff --color B

then this will give you a output of

enter image description here

The important point about this is

  1. Text in green is inside present in Branch A

  2. Text in red is present in Branch B

Removing legend on charts with chart.js v2

The options object can be added to the chart when the new Chart object is created.

var chart1 = new Chart(canvas, {
    type: "pie",
    data: data,
    options: {
         legend: {
            display: false
         },
         tooltips: {
            enabled: false
         }
    }
});

How to stop the Timer in android?

and.. we must call "waitTimer.purge()" for the GC. If you don't use Timer anymore, "purge()" !! "purge()" removes all canceled tasks from the task queue.

if(waitTimer != null) {
   waitTimer.cancel();
   waitTimer.purge();
   waitTimer = null;
}

Node.js - SyntaxError: Unexpected token import

In my case it was looking after .babelrc file, and it should contain something like this:

{
  "presets": ["es2015-node5", "stage-3"],
  "plugins": []
}

JavaFX Location is not set error message

I was getting this exception and the "solution" I found was through Netbeans IDE, simply:

  1. Right-click -> "Clean and Build"
  2. Run project again

I don't know WHY this worked, but it did!

Big O, how do you calculate/approximate it?

What often gets overlooked is the expected behavior of your algorithms. It doesn't change the Big-O of your algorithm, but it does relate to the statement "premature optimization. . .."

Expected behavior of your algorithm is -- very dumbed down -- how fast you can expect your algorithm to work on data you're most likely to see.

For instance, if you're searching for a value in a list, it's O(n), but if you know that most lists you see have your value up front, typical behavior of your algorithm is faster.

To really nail it down, you need to be able to describe the probability distribution of your "input space" (if you need to sort a list, how often is that list already going to be sorted? how often is it totally reversed? how often is it mostly sorted?) It's not always feasible that you know that, but sometimes you do.

console.log(result) returns [object Object]. How do I get result.name?

Try adding JSON.stringify(result) to convert the JS Object into a JSON string.

From your code I can see you are logging the result in error which is called if the AJAX request fails, so I'm not sure how you'd go about accessing the id/name/etc. then (you are checking for success inside the error condition!).

Note that if you use Chrome's console you should be able to browse through the object without having to stringify the JSON, which makes it easier to debug.

window.onload vs $(document).ready()

_x000D_
_x000D_
$(document).ready(function() {_x000D_
_x000D_
    // Executes when the HTML document is loaded and the DOM is ready_x000D_
    alert("Document is ready");_x000D_
});_x000D_
_x000D_
// .load() method deprecated from jQuery 1.8 onward_x000D_
$(window).on("load", function() {_x000D_
_x000D_
     // Executes when complete page is fully loaded, including_x000D_
     // all frames, objects and images_x000D_
     alert("Window is loaded");_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

Multiple left joins on multiple tables in one query

The JOIN statements are also part of the FROM clause, more formally a join_type is used to combine two from_item's into one from_item, multiple one of which can then form a comma-separated list after the FROM. See http://www.postgresql.org/docs/9.1/static/sql-select.html .

So the direct solution to your problem is:

SELECT something
FROM
    master as parent LEFT JOIN second as parentdata
        ON parent.secondary_id = parentdata.id,
    master as child LEFT JOIN second as childdata
        ON child.secondary_id = childdata.id
WHERE parent.id = child.parent_id AND parent.parent_id = 'rootID'

A better option would be to only use JOIN's, as it has already been suggested.

What's a Good Javascript Time Picker?

CSS Gallery has variety of Time Pickers. Have a look.

Perifer Design's time picker is similar to google one

how to make a full screen div, and prevent size to be changed by content?

<html>
<div style="width:100%; height:100%; position:fixed; left:0;top:0;overflow:hidden;">

</div>
</html>

Connect to SQL Server through PDO using SQL Server Driver

try
{

    $conn = new PDO("sqlsrv:Server=$server_name;Database=$db_name;ConnectionPooling=0", "", "");
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

}
catch(PDOException $e)
{

    $e->getMessage();

}

Importing files from different folder

Worked for me in python3 on linux

import sys  
sys.path.append(pathToFolderContainingScripts)  
from scriptName import functionName #scriptName without .py extension  

Java String to JSON conversion

The name is present inside the data. You need to parse a JSON hierarchically to be able to fetch the data properly.

JSONObject jObject  = new JSONObject(output); // json
JSONObject data = jObject.getJSONObject("data"); // get data object
String projectname = data.getString("name"); // get the name from data.

Note: This example uses the org.json.JSONObject class and not org.json.simple.JSONObject.


As "Matthew" mentioned in the comments that he is using org.json.simple.JSONObject, I'm adding my comment details in the answer.

Try to use the org.json.JSONObject instead. But then if you can't change your JSON library, you can refer to this example which uses the same library as yours and check the how to read a json part from it.

Sample from the link provided:

JSONObject jsonObject = (JSONObject) obj;
String name = (String) jsonObject.get("name");

How to pass params with history.push/Link/Redirect in react-router v4?

Extending the solution (suggested by Shubham Khatri) for use with React hooks (16.8 onwards):

package.json (always worth updating to latest packages)

{
     ...

     "react": "^16.12.0",
     "react-router-dom": "^5.1.2",

     ...
}

Passing parameters with history push:

import { useHistory } from "react-router-dom";

const FirstPage = props => {
    let history = useHistory();

    const someEventHandler = event => {
       history.push({
           pathname: '/secondpage',
           search: '?query=abc',
           state: { detail: 'some_value' }
       });
    };

};

export default FirstPage;


Accessing the passed parameter using useLocation from 'react-router-dom':

import { useEffect } from "react";
import { useLocation } from "react-router-dom";

const SecondPage = props => {
    const location = useLocation();

    useEffect(() => {
       console.log(location.pathname); // result: '/secondpage'
       console.log(location.search); // result: '?query=abc'
       console.log(location.state.detail); // result: 'some_value'
    }, [location]);

};

How can I delete a query string parameter in JavaScript?

const params = new URLSearchParams(location.search)
params.delete('key_to_delete')
console.log(params.toString())

Setting session variable using javascript

You can use

sessionStorage.SessionName = "SessionData" ,

sessionStorage.getItem("SessionName") and

sessionStorage.setItem("SessionName","SessionData");

See the supported browsers on http://caniuse.com/namevalue-storage

Freeze screen in chrome debugger / DevTools panel for popover inspection?

Got it working. Here was my procedure:

  1. Browse to the desired page
  2. Open the dev console - F12 on Windows/Linux or option + ? + J on macOS
  3. Select the Sources tab in chrome inspector
  4. In the web browser window, hover over the desired element to initiate the popover
  5. Hit F8 on Windows/Linux (or fn + F8 on macOS) while the popover is showing. If you have clicked anywhere on the actual page F8 will do nothing. Your last click needs to be somewhere in the inspector, like the sources tab
  6. Go to the Elements tab in inspector
  7. Find your popover (it will be nested in the trigger element's HTML)
  8. Have fun modifying the CSS

CSS grid wrapping

You want either auto-fit or auto-fill inside the repeat() function:

grid-template-columns: repeat(auto-fit, 186px);

The difference between the two becomes apparent if you also use a minmax() to allow for flexible column sizes:

grid-template-columns: repeat(auto-fill, minmax(186px, 1fr));

This allows your columns to flex in size, ranging from 186 pixels to equal-width columns stretching across the full width of the container. auto-fill will create as many columns as will fit in the width. If, say, five columns fit, even though you have only four grid items, there will be a fifth empty column:

Enter image description here

Using auto-fit instead will prevent empty columns, stretching yours further if necessary:

Enter image description here

How to set portrait and landscape media queries in css?

iPad Media Queries (All generations - including iPad mini)

Thanks to Apple's work in creating a consistent experience for users, and easy time for developers, all 5 different iPads (iPads 1-5 and iPad mini) can be targeted with just one CSS media query. The next few lines of code should work perfect for a responsive design.

iPad in portrait & landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px)  { /* STYLES GO HERE */}

iPad in landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : landscape) { /* STYLES GO HERE */}

iPad in portrait

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : portrait) { /* STYLES GO HERE */ }

iPad 3 & 4 Media Queries

If you're looking to target only 3rd and 4th generation Retina iPads (or tablets with similar resolution) to add @2x graphics, or other features for the tablet's Retina display, use the following media queries.

Retina iPad in portrait & landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px)
and (-webkit-min-device-pixel-ratio: 2) { /* STYLES GO HERE */}

Retina iPad in landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : landscape)
and (-webkit-min-device-pixel-ratio: 2) { /* STYLES GO HERE */}

Retina iPad in portrait

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : portrait)
and (-webkit-min-device-pixel-ratio: 2) { /* STYLES GO HERE */ }

iPad 1 & 2 Media Queries

If you're looking to supply different graphics or choose different typography for the lower resolution iPad display, the media queries below will work like a charm in your responsive design!

iPad 1 & 2 in portrait & landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (-webkit-min-device-pixel-ratio: 1){ /* STYLES GO HERE */}

iPad 1 & 2 in landscape

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : landscape)
and (-webkit-min-device-pixel-ratio: 1)  { /* STYLES GO HERE */}

iPad 1 & 2 in portrait

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : portrait) 
and (-webkit-min-device-pixel-ratio: 1) { /* STYLES GO HERE */ }

Source: http://stephen.io/mediaqueries/

Looking to understand the iOS UIViewController lifecycle

As per Apple's doc — Start Developing iOS Apps (Swift) — Work with View Controllers — Understand the View Controller Lifecycle

viewDidLoad()—Called when the view controller’s content view (the top of its view hierarchy) is created and loaded from a storyboard. … Use this method to perform any additional setup required by your view controller.

viewWillAppear()—Called just before the view controller’s content view is added to the app’s view hierarchy. Use this method to trigger any operations that need to occur before the content view is presented onscreen

viewDidAppear()—Called just after the view controller’s content view has been added to the app’s view hierarchy. Use this method to trigger any operations that need to occur as soon as the view is presented onscreen, such as fetching data or showing an animation.

viewWillDisappear()—Called just before the view controller’s content view is removed from the app’s view hierarchy. Use this method to perform cleanup tasks like committing changes or resigning the first responder status.

viewDidDisappear()—Called just after the view controller’s content view has been removed from the app’s view hierarchy. Use this method to perform additional teardown activities.

Angular 4.3 - HttpClient set params

Just wanted to add that if you want to add several parameters with the same key name for example: www.test.com/home?id=1&id=2

let params = new HttpParams();
params = params.append(key, value);

Use append, if you use set, it will overwrite the previous value with the same key name.

How do I remove files saying "old mode 100755 new mode 100644" from unstaged changes in Git?

This solution will change the git file permissions from 100755 to 100644 and push changes back to the bitbucket remote repo.

  1. Take a look at your repo's file permissions: git ls-files --stage

  2. If 100755 and you want 100644

Then run this command: git ls-files --stage | sed 's/\t/ /g' | cut -d' ' -f4 | xargs git update-index --chmod=-x

  1. Now check your repo's file permissions again: git ls-files --stage

  2. Now commit your changes:

git status

git commit -m "restored proper file permissions"

git push

jQuery ID starts with

try:

$("td[id^=" + value + "]")

How to format a URL to get a file from Amazon S3?

Its actually formulated more like:

https://<bucket-name>.s3.amazonaws.com/<key>

See here

How to delete a whole folder and content?

You can not delete the directory if it has subdirectories or files in Java. Try this two-line simple solution. This will delete the directory and contests inside the directory.

File dirName = new File("directory path");
FileUtils.deleteDirectory(dirName);

Add this line in gradle file and sync the project

compile 'org.apache.commons:commons-io:1.3.2'  

Generate random number between two numbers in JavaScript

I wrote more flexible function which can give you random number but not only integer.

function rand(min,max,interval)
{
    if (typeof(interval)==='undefined') interval = 1;
    var r = Math.floor(Math.random()*(max-min+interval)/interval);
    return r*interval+min;
}

var a = rand(0,10); //can be 0, 1, 2 (...) 9, 10
var b = rand(4,6,0.1); //can be 4.0, 4.1, 4.2 (...) 5.9, 6.0

Fixed version.

No visible cause for "Unexpected token ILLEGAL"

Here is my reason:

before:

var path = "D:\xxx\util.s"

which \u is a escape, I figured it out by using Codepen's analyze JS.

after:

var path = "D:\\xxx\\util.s"

and the error fixed

In Subversion can I be a user other than my login name?

TortoiseSVN always prompts for username. (unless you tell it not to)

How to concatenate strings of a string field in a PostgreSQL 'group by' query?

I found this PostgreSQL documentation helpful: http://www.postgresql.org/docs/8.0/interactive/functions-conditional.html.

In my case, I sought plain SQL to concatenate a field with brackets around it, if the field is not empty.

select itemid, 
  CASE 
    itemdescription WHEN '' THEN itemname 
    ELSE itemname || ' (' || itemdescription || ')' 
  END 
from items;

How to revert a merge commit that's already pushed to remote branch?

I also faced this issue on a PR that has been merged to the master branch of a GitHub repo.

Since I just wanted to modify some modified files but not the whole changes the PR brought, I had to amend the merge commit with git commit --am.

Steps:

  1. Go to the branch which you want to change / revert some modified files
  2. Do the changes you want according to modified files
  3. run git add * or git add <file>
  4. run git commit --am and validate
  5. run git push -f

Why it's interesting:

  • It keeps the PR's author commit unchanged
  • It doesn't break the git tree
  • You'll be marked as committer (merge commit author will remain unchanged)
  • Git act as if you resolved conflicts, it will remove / change the code in modified files as if you manually tell GitHub to not merge it as-is

PHP - cannot use a scalar as an array warning

The Other Issue I have seen on this is when nesting arrays this tends to throw the warning, consider the following:

$data = [
"rs" => null
]

this above will work absolutely fine when used like:

$data["rs"] =  5;

But the below will throw a warning ::

$data = [
    "rs" => [
       "rs1" => null;
       ]
    ]
..

$data[rs][rs1] = 2; // this will throw the warning unless assigned to an array

Firefox and SSL: sec_error_unknown_issuer

I had this problem with Firefox and my server. I contacted GoDaddy customer support, and they had me install the intermediate server certificate:

http://support.godaddy.com/help/article/868/what-is-an-intermediate-certificate

After a re-start of the World Wide Web Publishing Service, everything worked perfectly.

If you do not have full access to your server, your ISP will have to do this for you.

How do I exit a foreach loop in C#?

Use break.


Unrelated to your question, I see in your code the line:

Violated = !(name.firstname == null) ? false : true;

In this line, you take a boolean value (name.firstname == null). Then, you apply the ! operator to it. Then, if the value is true, you set Violated to false; otherwise to true. So basically, Violated is set to the same value as the original expression (name.firstname == null). Why not use that, as in:

Violated = (name.firstname == null);

Should I use .done() and .fail() for new jQuery AJAX code instead of success and error

As stated by user2246674, using success and error as parameter of the ajax function is valid.

To be consistent with precedent answer, reading the doc :

Deprecation Notice:

The jqXHR.success(), jqXHR.error(), and jqXHR.complete() callbacks will be deprecated in jQuery 1.8. To prepare your code for their eventual removal, use jqXHR.done(), jqXHR.fail(), and jqXHR.always() instead.

If you are using the callback-manipulation function (using method-chaining for example), use .done(), .fail() and .always() instead of success(), error() and complete().

IntelliJ shortcut to show a popup of methods in a class that can be searched

For Mac Users if command + fn + f12 or command + f12 is not working, then your key map is not selected as "Mac Os X". To select key map follow the below steps.

Android Studio -> Preferences -> Keymap -> From the drop down Select "Mac OS X" -> Click Apply -> OK.

How can I determine the status of a job?

This is what I'm using to get the running jobs (principally so I can kill the ones which have probably hung):

SELECT
    job.Name, job.job_ID
    ,job.Originating_Server
    ,activity.run_requested_Date
    ,datediff(minute, activity.run_requested_Date, getdate()) AS Elapsed
FROM
    msdb.dbo.sysjobs_view job 
        INNER JOIN msdb.dbo.sysjobactivity activity
        ON (job.job_id = activity.job_id)
WHERE
    run_Requested_date is not null 
    AND stop_execution_date is null
    AND job.name like 'Your Job Prefix%'

As Tim said, the MSDN / BOL documentation is reasonably good on the contents of the sysjobsX tables. Just remember they are tables in MSDB.

Tracking changes in Windows registry

I concur with Franci, all Sysinternals utilities are worth taking a look (Autoruns is a must too), and Process Monitor, which replaces the good old Filemon and Regmon is precious.

Beside the usage you want, it is very useful to see why a process fails (like trying to access a file or a registry key that doesn't exist), etc.

How do I write JSON data to a file?

if you are trying to write a pandas dataframe into a file using a json format i'd recommend this

destination='filepath'
saveFile = open(destination, 'w')
saveFile.write(df.to_json())
saveFile.close()

Folder is locked and I can't unlock it

To unlock a blocked document: 1. Right click -> Lock 2. Check the "Steal the locks" check box 2. Release the lock

Should composer.lock be committed to version control?

After doing it both ways for a few projects my stance is that composer.lock should not be committed as part of the project.

composer.lock is build metadata which is not part of the project. The state of dependencies should be controlled through how you're versioning them (either manually or as part of your automated build process) and not arbitrarily by the last developer to update them and commit the lock file.

If you are concerned about your dependencies changing between composer updates then you have a lack of confidence in your versioning scheme. Versions (1.0, 1.1, 1.2, etc) should be immutable and you should avoid "dev-" and "X.*" wildcards outside of initial feature development.

Committing the lock file is a regression for your dependency management system as the dependency version has now gone back to being implicitly defined.

Also, your project should never have to be rebuilt or have its dependencies reacquired in each environment, especially prod. Your deliverable (tar, zip, phar, a directory, etc) should be immutable and promoted through environments without changing.

How to pass the values from one jsp page to another jsp without submit button?

I am trying to Understand your Question and it seems that you want the values in the first JSP to be available in the Second JSP.

  1. It is very bad Habit to Place Java Code snippets Inside JSP file, so that code snippet should go to a servlet.

  2. Pick the values in a servlet ie.

    String username = request.getParameter("username");
    String password = request.getParameter("password");
    
  3. Then Store the Values inside the Session:

    HttpSession sess = request.getSession(); 
    sess.setAttribute("username", username);
    sess.setAttribute("password", password);
    
  4. These values Will be available anywhere in the Application as long as the session is valid.

    HttpSession sess = request.getSession(false); //use false to use the existing session
    sess.getAttribute("username");//this will return username anytime in the session
    sess.getAttribute("password");//this will return password Any time in the session
    

I hope this is what you wanted to know, but please do not use code snippets in the JSP. You can always get the values into the JSP using jstl in the JSPs:

 ${username}//this will give you the username in the JSP
 ${password}// this will give you the password in the JSP

Centering controls within a form in .NET (Winforms)?

Since you don't state if the form can resize or not there is an easy way if you don't care about resizing (if you do care, go with Mitch Wheats solution):

Select the control -> Format (menu option) -> Center in Window -> Horizontally or Vertically

Java JDBC connection status

If you are using MySQL

public static boolean isDbConnected() {
    final String CHECK_SQL_QUERY = "SELECT 1";
    boolean isConnected = false;
    try {
        final PreparedStatement statement = db.prepareStatement(CHECK_SQL_QUERY);
        isConnected = true;
    } catch (SQLException | NullPointerException e) {
        // handle SQL error here!
    }
    return isConnected;
}

I have not tested with other databases. Hope this is helpful.

How do I extract a substring from a string until the second space is encountered?

I was thinking about this problem for my own code and even though I probably will end up using something simpler/faster, here's another Linq solution that's similar to one that @Francisco added.

I just like it because it reads the most like what you actually want to do: "Take chars while the resulting substring has fewer than 2 spaces."

string input = "o1 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467";
var substring = input.TakeWhile((c0, index) => 
                                input.Substring(0, index + 1).Count(c => c == ' ') < 2);
string result = new String(substring.ToArray());

Working with TIFFs (import, export) in Python using numpy

You can also use pytiff of which I'm the author.

    import pytiff

    with pytiff.Tiff("filename.tif") as handle:
        part = handle[100:200, 200:400]

    # multipage tif
    with pytiff.Tiff("multipage.tif") as handle:
        for page in handle:
            part = page[100:200, 200:400]

It's a fairly small module and may not have as many features as other modules, but it supports tiled tiffs and bigtiff, so you can read parts of large images.

How to use BeanUtils.copyProperties?

As you can see in the below source code, BeanUtils.copyProperties internally uses reflection and there's additional internal cache lookup steps as well which is going to add cost wrt performance

 private static void copyProperties(Object source, Object target, @Nullable Class<?> editable,
                @Nullable String... ignoreProperties) throws BeansException {

            Assert.notNull(source, "Source must not be null");
            Assert.notNull(target, "Target must not be null");

            Class<?> actualEditable = target.getClass();
            if (editable != null) {
                if (!editable.isInstance(target)) {
                    throw new IllegalArgumentException("Target class [" + target.getClass().getName() +
                            "] not assignable to Editable class [" + editable.getName() + "]");
                }
                actualEditable = editable;
            }
            **PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);**
            List<String> ignoreList = (ignoreProperties != null ? Arrays.asList(ignoreProperties) : null);

            for (PropertyDescriptor targetPd : targetPds) {
                Method writeMethod = targetPd.getWriteMethod();
                if (writeMethod != null && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {
                    PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                    if (sourcePd != null) {
                        Method readMethod = sourcePd.getReadMethod();
                        if (readMethod != null &&
                                ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {
                            try {
                                if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
                                    readMethod.setAccessible(true);
                                }
                                Object value = readMethod.invoke(source);
                                if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
                                    writeMethod.setAccessible(true);
                                }
                                writeMethod.invoke(target, value);
                            }
                            catch (Throwable ex) {
                                throw new FatalBeanException(
                                        "Could not copy property '" + targetPd.getName() + "' from source to target", ex);
                            }
                        }
                    }
                }
            }
        }

So it's better to use plain setters given the cost reflection

Does uninstalling a package with "pip" also remove the dependent packages?

I have found the solution even though it might be a little difficult for some to carry out.

1st step (for python3 and linux):
pip3 install pip-autoremove
2nd step:
cd /home/usernamegoeshere/.local/bin/
3rd step:
gedit /home/usernamegoeshere/.local/lib/python3.8/site-packages/pip_autoremove.py
and change all pip(s) to pip3 4th step: ./pip-autoremove packagenamegoeshere

At least, this was what worked for me ...

PHP Regex to get youtube video ID?

(?<=\?v=)([a-zA-Z0-9_-]){11}

This should do it as well.

List comprehension vs. lambda + filter

I thought I'd just add that in python 3, filter() is actually an iterator object, so you'd have to pass your filter method call to list() in order to build the filtered list. So in python 2:

lst_a = range(25) #arbitrary list
lst_b = [num for num in lst_a if num % 2 == 0]
lst_c = filter(lambda num: num % 2 == 0, lst_a)

lists b and c have the same values, and were completed in about the same time as filter() was equivalent [x for x in y if z]. However, in 3, this same code would leave list c containing a filter object, not a filtered list. To produce the same values in 3:

lst_a = range(25) #arbitrary list
lst_b = [num for num in lst_a if num % 2 == 0]
lst_c = list(filter(lambda num: num %2 == 0, lst_a))

The problem is that list() takes an iterable as it's argument, and creates a new list from that argument. The result is that using filter in this way in python 3 takes up to twice as long as the [x for x in y if z] method because you have to iterate over the output from filter() as well as the original list.

What should be the sizeof(int) on a 64-bit machine?

In C++, the size of int isn't specified explicitly. It just tells you that it must be at least the size of short int, which must be at least as large as signed char. The size of char in bits isn't specified explicitly either, although sizeof(char) is defined to be 1. If you want a 64 bit int, C++11 specifies long long to be at least 64 bits.

disable editing default value of text input

Probably due to the fact that I could not explain well you do not really understand my question. In general, I found the solution.

Sorry for my english

Loading basic HTML in Node.js

You can echo files manually using the fs object, but I'd recommend using the ExpressJS framework to make your life much easier.

...But if you insist on doing it the hard way:

var http = require('http');
var fs = require('fs');

http.createServer(function(req, res){
    fs.readFile('test.html',function (err, data){
        res.writeHead(200, {'Content-Type': 'text/html','Content-Length':data.length});
        res.write(data);
        res.end();
    });
}).listen(8000);

Why can't I have abstract static methods in C#?

The abstract methods are implicitly virtual. Abstract methods require an instance, but static methods do not have an instance. So, you can have a static method in an abstract class, it just cannot be static abstract (or abstract static).

Bootstrap 4 - Responsive cards in card-columns

Another late answer, but I was playing with this and came up with a general purpose Sass solution that I found useful and many others might as well. To give an overview, this introduces new classes that can modify the column count of a .card-columns element in very similar ways to columns with .col-4 or .col-lg-3:

@import "bootstrap";

$card-column-counts: 1, 2, 3, 4, 5;

.card-columns {
    @each $column-count in $card-column-counts {
        &.card-columns-#{$column-count} {
            column-count: $column-count;
        }
    }

    @each $breakpoint in map-keys($grid-breakpoints) {
        @include media-breakpoint-up($breakpoint) {
            $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
            @each $column-count in $card-column-counts {
                &.card-columns#{$infix}-#{$column-count} {
                    column-count: $column-count;
                }
            }
        }
    }
}

The end result of this is if you have the following:

<div class="card-columns card-columns-2 card-columns-md-3 card-columns-xl-4">
   ...
</div>

Then you would have 2 columns by default, 3 for medium devices and up and 4 for xl devices and up. Additionally if you change your grid breakpoints this will automatically support those, and the $card-column-counts can be overridden to change the allowed numbers of columns.

Basic communication between two fragments

Update

Ignore this answer. Not that it doesn't work. But there are better methods available. Moreover, Android emphatically discourage direct communication between fragments. See official doc. Thanks user @Wahib Ul Haq for the tip.

Original Answer

Well, you can create a private variable and setter in Fragment B, and set the value from Fragment A itself,

FragmentB.java

private String inputString;
....
....

public void setInputString(String string){
   inputString = string;
}

FragmentA.java

//go to fragment B

FragmentB frag  = new FragmentB();
frag.setInputString(YOUR_STRING);
//create your fragment transaction object, set animation etc
fragTrans.replace(ITS_ARGUMENTS)

Or you can use Activity as you suggested in question..

How to display a Windows Form in full screen on top of the taskbar?

My simple fix it turned out to be calling the form's Activate() method, so there's no need to use TopMost (which is what I was aiming at).

setTimeout or setInterval?

The difference is obvious in console:

enter image description here

Range with step of type float

You could use numpy.arange.

EDIT: The docs prefer numpy.linspace. Thanks @Droogans for noticing =)

Matplotlib 2 Subplots, 1 Colorbar

This topic is well covered but I still would like to propose another approach in a slightly different philosophy.

It is a bit more complex to set-up but it allow (in my opinion) a bit more flexibility. For example, one can play with the respective ratios of each subplots / colorbar:

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.gridspec import GridSpec

# Define number of rows and columns you want in your figure
nrow = 2
ncol = 3

# Make a new figure
fig = plt.figure(constrained_layout=True)

# Design your figure properties
widths = [3,4,5,1]
gs = GridSpec(nrow, ncol + 1, figure=fig, width_ratios=widths)

# Fill your figure with desired plots
axes = []
for i in range(nrow):
    for j in range(ncol):
        axes.append(fig.add_subplot(gs[i, j]))
        im = axes[-1].pcolormesh(np.random.random((10,10)))

# Shared colorbar    
axes.append(fig.add_subplot(gs[:, ncol]))
fig.colorbar(im, cax=axes[-1])

plt.show()

enter image description here

in iPhone App How to detect the screen resolution of the device

See the UIScreen Reference: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIScreen_Class/Reference/UIScreen.html

if([[UIScreen mainScreen] respondsToSelector:NSSelectorFromString(@"scale")])
{
    if ([[UIScreen mainScreen] scale] < 1.1)
        NSLog(@"Standard Resolution Device");

    if ([[UIScreen mainScreen] scale] > 1.9)
        NSLog(@"High Resolution Device");
}

sqlite copy data from one table to another

I've been wrestling with this, and I know there are other options, but I've come to the conclusion the safest pattern is:

create table destination_old as select * from destination;

drop table destination;

create table destination as select
d.*, s.country
from destination_old d left join source s
on d.id=s.id;

It's safe because you have a copy of destination before you altered it. I suspect that update statements with joins weren't included in SQLite because they're powerful but a bit risky.

Using the pattern above you end up with two country fields. You can avoid that by explicitly stating all of the columns you want to retrieve from destination_old and perhaps using coalesce to retrieve the values from destination_old if the country field in source is null. So for example:

create table destination as select
d.field1, d.field2,...,coalesce(s.country,d.country) country
from destination_old d left join source s
on d.id=s.id;

What is the best way to find the users home directory in Java?

If you want something that works well on windows there is a package called WinFoldersJava which wraps the native call to get the 'special' directories on Windows. We use it frequently and it works well.

jQuery prevent change for select

You can do this without jquery...

<select onchange="event.target.selectedIndex = 0">
...
</select>

or you can do a function to check your condition

<select onchange="check(event)">
...
</select>

<script>
function check(e){
    if (my_condition){
        event.target.selectedIndex = 0;
    }
}
</script>

Comparing a variable with a string python not working when redirecting from bash script

When you read() the file, you may get a newline character '\n' in your string. Try either

if UserInput.strip() == 'List contents': 

or

if 'List contents' in UserInput: 

Also note that your second file open could also use with:

with open('/Users/.../USER_INPUT.txt', 'w+') as UserInputFile:     if UserInput.strip() == 'List contents': # or if s in f:         UserInputFile.write("ls")     else:         print "Didn't work" 

Cannot get to $rootScope

You can not ask for instance during configuration phase - you can ask only for providers.

var app = angular.module('modx', []);

// configure stuff
app.config(function($routeProvider, $locationProvider) {
  // you can inject any provider here
});

// run blocks
app.run(function($rootScope) {
  // you can inject any instance here
});

See http://docs.angularjs.org/guide/module for more info.

Regular Expression for password validation

Is a regular expression an easier/better way to enforce a simple constraint than the more obvious way?

static bool ValidatePassword( string password )
{
  const int MIN_LENGTH =  8 ;
  const int MAX_LENGTH = 15 ;

  if ( password == null ) throw new ArgumentNullException() ;

  bool meetsLengthRequirements = password.Length >= MIN_LENGTH && password.Length <= MAX_LENGTH ;
  bool hasUpperCaseLetter      = false ;
  bool hasLowerCaseLetter      = false ;
  bool hasDecimalDigit         = false ;

  if ( meetsLengthRequirements )
  {
    foreach (char c in password )
    {
      if      ( char.IsUpper(c) ) hasUpperCaseLetter = true ;
      else if ( char.IsLower(c) ) hasLowerCaseLetter = true ;
      else if ( char.IsDigit(c) ) hasDecimalDigit    = true ;
    }
  }

  bool isValid = meetsLengthRequirements
              && hasUpperCaseLetter
              && hasLowerCaseLetter
              && hasDecimalDigit
              ;
  return isValid ;

}

Which do you think that maintenance programmer 3 years from now who needs to modify the constraint will have an easier time understanding?

A terminal command for a rooted Android to remount /System as read/write

I use this command:

mount -o rw,remount /system

How can I store and retrieve images from a MySQL database using PHP?

First you create a MySQL table to store images, like for example:

create table testblob (
    image_id        tinyint(3)  not null default '0',
    image_type      varchar(25) not null default '',
    image           blob        not null,
    image_size      varchar(25) not null default '',
    image_ctgy      varchar(25) not null default '',
    image_name      varchar(50) not null default ''
);

Then you can write an image to the database like:

/***
 * All of the below MySQL_ commands can be easily
 * translated to MySQLi_ with the additions as commented
 ***/ 
$imgData = file_get_contents($filename);
$size = getimagesize($filename);
mysql_connect("localhost", "$username", "$password");
mysql_select_db ("$dbname");
// mysqli 
// $link = mysqli_connect("localhost", $username, $password,$dbname); 
$sql = sprintf("INSERT INTO testblob
    (image_type, image, image_size, image_name)
    VALUES
    ('%s', '%s', '%d', '%s')",
    /***
     * For all mysqli_ functions below, the syntax is:
     * mysqli_whartever($link, $functionContents); 
     ***/
    mysql_real_escape_string($size['mime']),
    mysql_real_escape_string($imgData),
    $size[3],
    mysql_real_escape_string($_FILES['userfile']['name'])
    );
mysql_query($sql);

You can display an image from the database in a web page with:

$link = mysql_connect("localhost", "username", "password");
mysql_select_db("testblob");
$sql = "SELECT image FROM testblob WHERE image_id=0";
$result = mysql_query("$sql");
header("Content-type: image/jpeg");
echo mysql_result($result, 0);
mysql_close($link);

How to add a single item to a Pandas Series

Here is another thought n for appending multiple items in one line without changing the name of series. However, this may be not as efficient as the other answer.

>>> df = pd.Series(np.random.random(5), name='random')
>>> df

0    0.363885
1    0.402623
2    0.450449
3    0.172917
4    0.983481
Name: random, dtype: float64


>>> df.to_frame().T.assign(a=3, b=2, c=5).squeeze()

0    0.363885
1    0.402623
2    0.450449
3    0.172917
4    0.983481
a    3.000000
b    2.000000
c    5.000000
Name: random, dtype: float64

Deep copy, shallow copy, clone

The term "clone" is ambiguous (though the Java class library includes a Cloneable interface) and can refer to a deep copy or a shallow copy. Deep/shallow copies are not specifically tied to Java but are a general concept relating to making a copy of an object, and refers to how members of an object are also copied.

As an example, let's say you have a person class:

class Person {
    String name;
    List<String> emailAddresses
}

How do you clone objects of this class? If you are performing a shallow copy, you might copy name and put a reference to emailAddresses in the new object. But if you modified the contents of the emailAddresses list, you would be modifying the list in both copies (since that's how object references work).

A deep copy would mean that you recursively copy every member, so you would need to create a new List for the new Person, and then copy the contents from the old to the new object.

Although the above example is trivial, the differences between deep and shallow copies are significant and have a major impact on any application, especially if you are trying to devise a generic clone method in advance, without knowing how someone might use it later. There are times when you need deep or shallow semantics, or some hybrid where you deep copy some members but not others.

Fitting a Normal distribution to 1D data

To see both the normal distribution and your actual data you should plot your data as a histogram, then draw the probability density function over this. See the example on https://docs.scipy.org/doc/numpy-1.15.0/reference/generated/numpy.random.normal.html for exactly how to do this.

Check whether there is an Internet connection available on Flutter app

enter image description here

Full example demonstrating a listener of the internet connectivity and its source.

Credit to : connectivity and Günter Zöchbauer

import 'dart:async';
import 'dart:io';
import 'package:connectivity/connectivity.dart';
import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(home: HomePage()));

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  Map _source = {ConnectivityResult.none: false};
  MyConnectivity _connectivity = MyConnectivity.instance;

  @override
  void initState() {
    super.initState();
    _connectivity.initialise();
    _connectivity.myStream.listen((source) {
      setState(() => _source = source);
    });
  }

  @override
  Widget build(BuildContext context) {
    String string;
    switch (_source.keys.toList()[0]) {
      case ConnectivityResult.none:
        string = "Offline";
        break;
      case ConnectivityResult.mobile:
        string = "Mobile: Online";
        break;
      case ConnectivityResult.wifi:
        string = "WiFi: Online";
    }

    return Scaffold(
      appBar: AppBar(title: Text("Internet")),
      body: Center(child: Text("$string", style: TextStyle(fontSize: 36))),
    );
  }

  @override
  void dispose() {
    _connectivity.disposeStream();
    super.dispose();
  }
}

class MyConnectivity {
  MyConnectivity._internal();

  static final MyConnectivity _instance = MyConnectivity._internal();

  static MyConnectivity get instance => _instance;

  Connectivity connectivity = Connectivity();

  StreamController controller = StreamController.broadcast();

  Stream get myStream => controller.stream;

  void initialise() async {
    ConnectivityResult result = await connectivity.checkConnectivity();
    _checkStatus(result);
    connectivity.onConnectivityChanged.listen((result) {
      _checkStatus(result);
    });
  }

  void _checkStatus(ConnectivityResult result) async {
    bool isOnline = false;
    try {
      final result = await InternetAddress.lookup('example.com');
      if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
        isOnline = true;
      } else
        isOnline = false;
    } on SocketException catch (_) {
      isOnline = false;
    }
    controller.sink.add({result: isOnline});
  }

  void disposeStream() => controller.close();
}

How does spring.jpa.hibernate.ddl-auto property exactly work in Spring?

For the record, the spring.jpa.hibernate.ddl-auto property is Spring Data JPA specific and is their way to specify a value that will eventually be passed to Hibernate under the property it knows, hibernate.hbm2ddl.auto.

The values create, create-drop, validate, and update basically influence how the schema tool management will manipulate the database schema at startup.

For example, the update operation will query the JDBC driver's API to get the database metadata and then Hibernate compares the object model it creates based on reading your annotated classes or HBM XML mappings and will attempt to adjust the schema on-the-fly.

The update operation for example will attempt to add new columns, constraints, etc but will never remove a column or constraint that may have existed previously but no longer does as part of the object model from a prior run.

Typically in test case scenarios, you'll likely use create-drop so that you create your schema, your test case adds some mock data, you run your tests, and then during the test case cleanup, the schema objects are dropped, leaving an empty database.

In development, it's often common to see developers use update to automatically modify the schema to add new additions upon restart. But again understand, this does not remove a column or constraint that may exist from previous executions that is no longer necessary.

In production, it's often highly recommended you use none or simply don't specify this property. That is because it's common practice for DBAs to review migration scripts for database changes, particularly if your database is shared across multiple services and applications.

How to remove files from git staging area?

To remove all files from staging area use -
git reset
To remove specific file use -
git reset "File path"

how to refresh Select2 dropdown menu after ajax loading different content?

Finally solved issue of reinitialization of select2 after ajax call.

You can call this in success function of ajax.

Note : Don't forget to replace ".selector" to your class of <select class="selector"> element.

jQuery('.select2-container').remove();

jQuery('.selector').select2({
   placeholder: "Placeholder text",
   allowClear: true
});

jQuery('.select2-container').css('width','100%');

What is the size of a pointer?

To answer your other question. The size of a pointer and the size of what it points to are not related. A good analogy is to consider them like postal addresses. The size of the address of a house has no relationship to the size of the house.

How can I set / change DNS using the command-prompt at windows 8

First, the network name is likely "Ethernet", not "Local Area Connection". To find out the name you can do this:

netsh interface show interface

Which will show the name under the "Interface Name" column (shown here in bold):

Admin State    State          Type             Interface Name
-------------------------------------------------------------------------
Enabled        Connected      Dedicated        Ethernet

Now you can change the primary dns (index=1), assuming that your interface is static (not using dhcp):

netsh interface ipv4 add dnsserver "Ethernet" address=192.168.x.x index=1

2018 Update - The command will work with either dnsserver (singular) or dnsservers (plural). The following example uses the latter and is valid as well:

netsh interface ipv4 add dnsservers "Ethernet" address=192.168.x.x index=1

Named parameters in JDBC

Vanilla JDBC only supports named parameters in a CallableStatement (e.g. setString("name", name)), and even then, I suspect the underlying stored procedure implementation has to support it.

An example of how to use named parameters:

//uss Sybase ASE sysobjects table...adjust for your RDBMS
stmt = conn.prepareCall("create procedure p1 (@id int = null, @name varchar(255) = null) as begin "
        + "if @id is not null "
        + "select * from sysobjects where id = @id "
        + "else if @name is not null "
        + "select * from sysobjects where name = @name "
        + " end");
stmt.execute();

//call the proc using one of the 2 optional params
stmt = conn.prepareCall("{call p1 ?}");
stmt.setInt("@id", 10);
ResultSet rs = stmt.executeQuery();
while (rs.next())
{
    System.out.println(rs.getString(1));
}


//use the other optional param
stmt = conn.prepareCall("{call p1 ?}");
stmt.setString("@name", "sysprocedures");
rs = stmt.executeQuery();
while (rs.next())
{
    System.out.println(rs.getString(1));
}

HTML/JavaScript: Simple form validation on submit

HTML Form Element Validation

Run Function

<script>
    $("#validationForm").validation({
         button: "#btnGonder",
         onSubmit: function () {
             alert("Submit Process");
         },
         onCompleted: function () {
             alert("onCompleted");
         },
         onError: function () {
             alert("Error Process");
         }
    });
</script>

Go to example and download https://github.com/naimserin/Validation.

How do I redirect in expressjs while passing some context?

There are a few ways of passing data around to different routes. The most correct answer is, of course, query strings. You'll need to ensure that the values are properly encodeURIComponent and decodeURIComponent.

app.get('/category', function(req, res) {
  var string = encodeURIComponent('something that would break');
  res.redirect('/?valid=' + string);
});

You can snag that in your other route by getting the parameters sent by using req.query.

app.get('/', function(req, res) {
  var passedVariable = req.query.valid;
  // Do something with variable
});

For more dynamic way you can use the url core module to generate the query string for you:

const url = require('url');    
app.get('/category', function(req, res) {
    res.redirect(url.format({
       pathname:"/",
       query: {
          "a": 1,
          "b": 2,
          "valid":"your string here"
        }
     }));
 });

So if you want to redirect all req query string variables you can simply do

res.redirect(url.format({
       pathname:"/",
       query:req.query,
     });
 });

And if you are using Node >= 7.x you can also use the querystring core module

const querystring = require('querystring');    
app.get('/category', function(req, res) {
      const query = querystring.stringify({
          "a": 1,
          "b": 2,
          "valid":"your string here"
      });
      res.redirect('/?' + query);
 });

Another way of doing it is by setting something up in the session. You can read how to set it up here, but to set and access variables is something like this:

app.get('/category', function(req, res) {
  req.session.valid = true;
  res.redirect('/');
});

And later on after the redirect...

app.get('/', function(req, res) {
  var passedVariable = req.session.valid;
  req.session.valid = null; // resets session variable
  // Do something
});

There is also the option of using an old feature of Express, req.flash. Doing so in newer versions of Express will require you to use another library. Essentially it allows you to set up variables that will show up and reset the next time you go to a page. It's handy for showing errors to users, but again it's been removed by default. EDIT: Found a library that adds this functionality.

Hopefully that will give you a general idea how to pass information around in an Express application.

Gnuplot line types

Until version 4.6

The dash type of a linestyle is given by the linetype, which does also select the line color unless you explicitely set an other one with linecolor.

However, the support for dashed lines depends on the selected terminal:

  1. Some terminals don't support dashed lines, like png (uses libgd)
  2. Other terminals, like pngcairo, support dashed lines, but it is disables by default. To enable it, use set termoption dashed, or set terminal pngcairo dashed ....
  3. The exact dash patterns differ between terminals. To see the defined linetype, use the test command:

Running

set terminal pngcairo dashed
set output 'test.png'
test
set output

gives:

enter image description here

whereas, the postscript terminal shows different dash patterns:

set terminal postscript eps color colortext
set output 'test.eps'
test
set output

enter image description here

Version 5.0

Starting with version 5.0 the following changes related to linetypes, dash patterns and line colors are introduced:

  • A new dashtype parameter was introduced:

    To get the predefined dash patterns, use e.g.

    plot x dashtype 2
    

    You can also specify custom dash patterns like

    plot x dashtype (3,5,10,5),\
         2*x dashtype '.-_'
    
  • The terminal options dashed and solid are ignored. By default all lines are solid. To change them to dashed, use e.g.

    set for [i=1:8] linetype i dashtype i
    
  • The default set of line colors was changed. You can select between three different color sets with set colorsequence default|podo|classic:

enter image description here

Scroll to a specific Element Using html

Should you want to resort to using a plug-in, malihu-custom-scrollbar-plugin, could do the job. It performs an actual scroll, not just a jump. You can even specify the speed/momentum of scroll. It also lets you set up a menu (list of links to scroll to), which have their CSS changed based on whether the anchors-to-scroll-to are in viewport, and other useful features.

There are demo on the author's site and let our company site serve as a real-world example too.

What is the purpose of the "role" attribute in HTML?

Most of the roles you see were defined as part of ARIA 1.0, and then later incorporated into HTML via supporting specs like HTML-AAM. Some of the new HTML5 elements (dialog, main, etc.) are even based on the original ARIA roles.

http://www.w3.org/TR/wai-aria/

There are a few primary reasons to use roles in addition to your native semantic element.

Reason #1. Overriding the role where no host language element is appropriate or, for various reasons, a less semantically appropriate element was used.

In this example, a link was used, even though the resulting functionality is more button-like than a navigation link.

<a href="#" role="button" aria-label="Delete item 1">Delete</a>
<!-- Note: href="#" is just a shorthand here, not a recommended technique. Use progressive enhancement when possible. -->

Screen readers users will hear this as a button (as opposed to a link), and you can use a CSS attribute selector to avoid class-itis and div-itis.

[role="button"] {
  /* style these as buttons w/o relying on a .button class */
}

[Update 7 years later: removed the * selector to make some commenters happy, since the old browser quirk that required universal selector on attribute selectors is unnecessary in 2020.]

Reason #2. Backing up a native element's role, to support browsers that implemented the ARIA role but haven't yet implemented the native element's role.

For example, the "main" role has been supported in browsers for many years, but it's a relatively recent addition to HTML5, so many browsers don't yet support the semantic for <main>.

<main role="main">…</main>

This is technically redundant, but helps some users and doesn't harm any. In a few years, this technique will likely become unnecessary for main.

Reason #3. Update 7 years later (2020): As at least one commenter pointed out, this is now very useful for custom elements, and some spec work is underway to define the default accessibility role of a web component. Even if/once that API is standardized, there may be need to override the default role of a component.

Note/Reply

You also wrote:

I see some people make up their own. Is that allowed or a correct use of the role attribute?

That's an allowed use of the attribute unless a real role is not included. Browsers will apply the first recognized role in the token list.

<span role="foo link note bar">...</a>

Out of the list, only link and note are valid roles, and so the link role will be applied in the platform accessibility API because it comes first. If you use custom roles, make sure they don't conflict with any defined role in ARIA or the host language you're using (HTML, SVG, MathML, etc.)

How to move Docker containers between different hosts?

From Docker documentation:

docker export does not export the contents of volumes associated with the container. If a volume is mounted on top of an existing directory in the container, docker export will export the contents of the underlying directory, not the contents of the volume. Refer to Backup, restore, or migrate data volumes in the user guide for examples on exporting data in a volume.

Disable vertical scroll bar on div overflow: auto

If you want to accomplish the same in Gecko (NS6+, Mozilla, etc) and IE4+ simultaneously, I believe this should do the trick:V

body {
overflow: -moz-scrollbars-vertical;
overflow-x: hidden;
overflow-y: auto;
}

This will be applied to entire body tag, please update it to your relevant css and apply this properties.

Regex for empty string or white space

http://jsfiddle.net/DqGB8/1/

This is my solution

var error=0;
var test = [" ", "   "];
 if(test[0].match(/^\s*$/g)) {
     $("#output").html("MATCH!");
     error+=1;
 } else {
     $("#output").html("no_match");
 }

Parse XML using JavaScript

The following will parse an XML string into an XML document in all major browsers, including Internet Explorer 6. Once you have that, you can use the usual DOM traversal methods/properties such as childNodes and getElementsByTagName() to get the nodes you want.

var parseXml;
if (typeof window.DOMParser != "undefined") {
    parseXml = function(xmlStr) {
        return ( new window.DOMParser() ).parseFromString(xmlStr, "text/xml");
    };
} else if (typeof window.ActiveXObject != "undefined" &&
       new window.ActiveXObject("Microsoft.XMLDOM")) {
    parseXml = function(xmlStr) {
        var xmlDoc = new window.ActiveXObject("Microsoft.XMLDOM");
        xmlDoc.async = "false";
        xmlDoc.loadXML(xmlStr);
        return xmlDoc;
    };
} else {
    throw new Error("No XML parser found");
}

Example usage:

var xml = parseXml("<foo>Stuff</foo>");
alert(xml.documentElement.nodeName);

Which I got from https://stackoverflow.com/a/8412989/1232175.

Why does CSV file contain a blank line in between each data line when outputting with Dictwriter in Python

Changing the 'w' (write) in this line:

output = csv.DictWriter(open('file3.csv','w'), delimiter=',', fieldnames=headers)

To 'wb' (write binary) fixed this problem for me:

output = csv.DictWriter(open('file3.csv','wb'), delimiter=',', fieldnames=headers)

Python v2.75: Open()

Credit to @dandrejvv for the solution in the comment on the original post above.

Function vs. Stored Procedure in SQL Server

I realize this is a very old question, but I don't see one crucial aspect mentioned in any of the answers: inlining into query plan.

Functions can be...

  1. Scalar:

    CREATE FUNCTION ... RETURNS scalar_type AS BEGIN ... END

  2. Multi-statement table-valued:

    CREATE FUNCTION ... RETURNS @r TABLE(...) AS BEGIN ... END

  3. Inline table-valued:

    CREATE FUNCTION ... RETURNS TABLE AS RETURN SELECT ...

The third kind (inline table-valued) are treated by the query optimizer essentially as (parametrized) views, which means that referencing the function from your query is similar to copy-pasting the function's SQL body (without actually copy-pasting), leading to the following benefits:

  • The query planner can optimize the inline function's execution just as it would any other sub-query (e.g. eliminate unused columns, push predicates down, pick different JOIN strategies etc.).
  • Combining several inline function doesn't require materializing the result from the first one before feeding it to the next.

The above can lead to potentially significant performance savings, especially when combining multiple levels of functions.


NOTE: Looks like SQL Server 2019 will introduce some form of scalar function inlining as well.

Splitting on last delimiter in Python string?

I just did this for fun

    >>> s = 'a,b,c,d'
    >>> [item[::-1] for item in s[::-1].split(',', 1)][::-1]
    ['a,b,c', 'd']

Caution: Refer to the first comment in below where this answer can go wrong.

Pass multiple values with onClick in HTML link

 $Name= "'".$row['Name']."'";
  $Val1= "'".$row['Val1']."'";
  $Year= "'".$row['Year']."'";
  $Month="'".$row['Month']."'";

 echo '<button type="button"   onclick="fun('.$Id.','.$Val1.','.$Year.','.$Month.','.$Id.');"  >submit</button>'; 

How do I disable the security certificate check in Python requests

From the documentation:

requests can also ignore verifying the SSL certificate if you set verify to False.

>>> requests.get('https://kennethreitz.com', verify=False)
<Response [200]>

If you're using a third-party module and want to disable the checks, here's a context manager that monkey patches requests and changes it so that verify=False is the default and suppresses the warning.

import warnings
import contextlib

import requests
from urllib3.exceptions import InsecureRequestWarning


old_merge_environment_settings = requests.Session.merge_environment_settings

@contextlib.contextmanager
def no_ssl_verification():
    opened_adapters = set()

    def merge_environment_settings(self, url, proxies, stream, verify, cert):
        # Verification happens only once per connection so we need to close
        # all the opened adapters once we're done. Otherwise, the effects of
        # verify=False persist beyond the end of this context manager.
        opened_adapters.add(self.get_adapter(url))

        settings = old_merge_environment_settings(self, url, proxies, stream, verify, cert)
        settings['verify'] = False

        return settings

    requests.Session.merge_environment_settings = merge_environment_settings

    try:
        with warnings.catch_warnings():
            warnings.simplefilter('ignore', InsecureRequestWarning)
            yield
    finally:
        requests.Session.merge_environment_settings = old_merge_environment_settings

        for adapter in opened_adapters:
            try:
                adapter.close()
            except:
                pass

Here's how you use it:

with no_ssl_verification():
    requests.get('https://wrong.host.badssl.com/')
    print('It works')

    requests.get('https://wrong.host.badssl.com/', verify=True)
    print('Even if you try to force it to')

requests.get('https://wrong.host.badssl.com/', verify=False)
print('It resets back')

session = requests.Session()
session.verify = True

with no_ssl_verification():
    session.get('https://wrong.host.badssl.com/', verify=True)
    print('Works even here')

try:
    requests.get('https://wrong.host.badssl.com/')
except requests.exceptions.SSLError:
    print('It breaks')

try:
    session.get('https://wrong.host.badssl.com/')
except requests.exceptions.SSLError:
    print('It breaks here again')

Note that this code closes all open adapters that handled a patched request once you leave the context manager. This is because requests maintains a per-session connection pool and certificate validation happens only once per connection so unexpected things like this will happen:

>>> import requests
>>> session = requests.Session()
>>> session.get('https://wrong.host.badssl.com/', verify=False)
/usr/local/lib/python3.7/site-packages/urllib3/connectionpool.py:857: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecureRequestWarning)
<Response [200]>
>>> session.get('https://wrong.host.badssl.com/', verify=True)
/usr/local/lib/python3.7/site-packages/urllib3/connectionpool.py:857: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecureRequestWarning)
<Response [200]>

Vuex - passing multiple parameters to mutation

In simple terms you need to build your payload into a key array

payload = {'key1': 'value1', 'key2': 'value2'}

Then send the payload directly to the action

this.$store.dispatch('yourAction', payload)

No change in your action

yourAction: ({commit}, payload) => {
  commit('YOUR_MUTATION',  payload )
},

In your mutation call the values with the key

'YOUR_MUTATION' (state,  payload ){
  state.state1 = payload.key1
  state.state2 =  payload.key2
},

How to change the text of a button in jQuery?

If you have button'ed your button this seems to work:

<button id="button">First caption</button>

$('#button').button();//make it nice
var text="new caption";
$('#button').children().first().html(text);

How to set background color of HTML element using css properties in JavaScript

you can use

$('#elementID').css('background-color', '#C0C0C0');

where is gacutil.exe?

gacutil comes with Visual Studio, not with VSTS. It is part of Windows SDK and can be download separately at http://www.microsoft.com/downloads/details.aspx?FamilyId=F26B1AA4-741A-433A-9BE5-FA919850BDBF&displaylang=en . This installation will have gacutil.exe included. But first check it here

C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin

you might have it installed.

As @devi mentioned

If you decide to grab gacutil files from existing installation, note that from .NET 4.0 is three files: gacutil.exe gacutil.exe.config and 1033/gacutlrc.dll

EntityType has no key defined error

There are several reasons this can happen. Some of these I found here, others I discovered on my own.

  • If the property is named something other than Id, you need to add the [Key] attribute to it.
  • The key needs to be a property, not a field.
  • The key needs to be public
  • The key needs to be a CLS-compliant type, meaning unsigned types like uint, ulong etc. are not allowed.
  • This error can also be caused by configuration mistakes.

PHP: Possible to automatically get all POSTed data?

As long as you don't want any special formatting: yes.

foreach ($_POST as $key => $value) 
    $body .= $key . ' -> ' . $value . '<br>';

Obviously, more formatting would be necessary, however that's the "easy" way. Unless I misunderstood the question.

You could also do something like this (and if you like the format, it's certainly easier):

$body = print_r($_POST, true);

Difference between a User and a Login in SQL Server

In Short,

Logins will have the access of the server.

and

Users will have the access of the database.

How do I view the SSIS packages in SQL Server Management Studio?

  1. you could find it under intergration services option in object explorer.
  2. you could find the packages under integration services catalog where all packages are deployed.

How do I count a JavaScript object's attributes?

You can do that by using this simple code:

Object.keys(myObject).length

Linq Query Group By and Selecting First Items

var result = list.GroupBy(x => x.Category).Select(x => x.First())

remove script tag from HTML content

$html = <<<HTML
...
HTML;
$dom = new DOMDocument();
$dom->loadHTML($html);
$tags_to_remove = array('script','style','iframe','link');
foreach($tags_to_remove as $tag){
    $element = $dom->getElementsByTagName($tag);
    foreach($element  as $item){
        $item->parentNode->removeChild($item);
    }
}
$html = $dom->saveHTML();

Should I use != or <> for not equal in T-SQL?

'<>' is from the SQL-92 standard and '!=' is a proprietary T-SQL operator. It's available in other databases as well, but since it isn't standard you have to take it on a case-by-case basis.

In most cases, you'll know what database you're connecting to so this isn't really an issue. At worst you might have to do a search and replace in your SQL.

ObservableCollection not noticing when Item in it changes (even with INotifyPropertyChanged)

Added to TruelyObservableCollection event "ItemPropertyChanged":

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel; // ObservableCollection
using System.ComponentModel; // INotifyPropertyChanged
using System.Collections.Specialized; // NotifyCollectionChangedEventHandler
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ObservableCollectionTest
{
    class Program
    {
        static void Main(string[] args)
        {
            // ATTN: Please note it's a "TrulyObservableCollection" that's instantiated. Otherwise, "Trades[0].Qty = 999" will NOT trigger event handler "Trades_CollectionChanged" in main.
            // REF: http://stackoverflow.com/questions/8490533/notify-observablecollection-when-item-changes
            TrulyObservableCollection<Trade> Trades = new TrulyObservableCollection<Trade>();
            Trades.Add(new Trade { Symbol = "APPL", Qty = 123 });
            Trades.Add(new Trade { Symbol = "IBM", Qty = 456});
            Trades.Add(new Trade { Symbol = "CSCO", Qty = 789 });

            Trades.CollectionChanged += Trades_CollectionChanged;
            Trades.ItemPropertyChanged += PropertyChangedHandler;
            Trades.RemoveAt(2);

            Trades[0].Qty = 999;

            Console.WriteLine("Hit any key to exit");
            Console.ReadLine();

            return;
        }

        static void PropertyChangedHandler(object sender, PropertyChangedEventArgs e)
        {
            Console.WriteLine(DateTime.Now.ToString() + ", Property changed: " + e.PropertyName + ", Symbol: " + ((Trade) sender).Symbol + ", Qty: " + ((Trade) sender).Qty);
            return;
        }

        static void Trades_CollectionChanged(object sender, EventArgs e)
        {
            Console.WriteLine(DateTime.Now.ToString() + ", Collection changed");
            return;
        }
    }

    #region TrulyObservableCollection
    public class TrulyObservableCollection<T> : ObservableCollection<T>
        where T : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler ItemPropertyChanged;

        public TrulyObservableCollection()
            : base()
        {
            CollectionChanged += new NotifyCollectionChangedEventHandler(TrulyObservableCollection_CollectionChanged);
        }

        void TrulyObservableCollection_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.NewItems != null)
            {
                foreach (Object item in e.NewItems)
                {
                    (item as INotifyPropertyChanged).PropertyChanged += new PropertyChangedEventHandler(item_PropertyChanged);
                }
            }
            if (e.OldItems != null)
            {
                foreach (Object item in e.OldItems)
                {
                    (item as INotifyPropertyChanged).PropertyChanged -= new PropertyChangedEventHandler(item_PropertyChanged);
                }
            }
        }

        void item_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            NotifyCollectionChangedEventArgs a = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
            OnCollectionChanged(a);

            if (ItemPropertyChanged != null)
            {
                ItemPropertyChanged(sender, e);
            }
        }
    }
    #endregion

    #region Sample entity
    class Trade : INotifyPropertyChanged
    {
        protected string _Symbol;
        protected int _Qty = 0;
        protected DateTime _OrderPlaced = DateTime.Now;

        public DateTime OrderPlaced
        {
            get { return _OrderPlaced; }
        }

        public string Symbol
        {
            get
            {
                return _Symbol;
            }
            set
            {
                _Symbol = value;
                NotifyPropertyChanged("Symbol");
            }
        }

        public int Qty
        {
            get
            {
                return _Qty;
            }
            set
            {
                _Qty = value;
                NotifyPropertyChanged("Qty");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String propertyName = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
#endregion
}

Remove portion of a string after a certain character

preg_replace offers one way:

$newText = preg_replace('/\bBy.*$/', '', $text);

Java serialization - java.io.InvalidClassException local class incompatible

@DanielChapman gives a good explanation of serialVersionUID, but no solution. the solution is this: run the serialver program on all your old classes. put these serialVersionUID values in your current versions of the classes. as long as the current classes are serial compatible with the old versions, you should be fine. (note for future code: you should always have a serialVersionUID on all Serializable classes)

if the new versions are not serial compatible, then you need to do some magic with a custom readObject implementation (you would only need a custom writeObject if you were trying to write new class data which would be compatible with old code). generally speaking adding or removing class fields does not make a class serial incompatible. changing the type of existing fields usually will.

Of course, even if the new class is serial compatible, you may still want a custom readObject implementation. you may want this if you want to fill in any new fields which are missing from data saved from old versions of the class (e.g. you have a new List field which you want to initialize to an empty list when loading old class data).

Unable to find the requested .Net Framework Data Provider in Visual Studio 2010 Professional

In my case the Data provider entry for MySQL was "simply" missing in the machine.config file described above (though I had installed the MySQL connector properly)

<add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.5.4.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />

Don't forget to put the right Version of your MySQL on the Entry

In Python, how do I loop through the dictionary and change the value if it equals something?

You could create a dict comprehension of just the elements whose values are None, and then update back into the original:

tmp = dict((k,"") for k,v in mydict.iteritems() if v is None)
mydict.update(tmp)

Update - did some performance tests

Well, after trying dicts of from 100 to 10,000 items, with varying percentage of None values, the performance of Alex's solution is across-the-board about twice as fast as this solution.

How can I lock a file using java (if possible)

If you can use Java NIO (JDK 1.4 or greater), then I think you're looking for java.nio.channels.FileChannel.lock()

FileChannel.lock()

how to find seconds since 1970 in java

Another option is to use the TimeUtils utility method:

TimeUtils.millisToUnit(System.currentTimeMillis(), TimeUnit.SECONDS)

Difference between 'struct' and 'typedef struct' in C++?

There is no difference in C++, but I believe in C it would allow you to declare instances of the struct Foo without explicitly doing:

struct Foo bar;

z-index not working with position absolute

Opacity changes the context of your z-index, as does the static positioning. Either add opacity to the element that doesn't have it or remove it from the element that does. You'll also have to either make both elements static positioned or specify relative or absolute position. Here's some background on contexts: http://philipwalton.com/articles/what-no-one-told-you-about-z-index/

MySQL - Make an existing Field Unique

This code is to solve our problem to set unique key for existing table

alter ignore table ioni_groups add unique (group_name);

How do I get the value of a textbox using jQuery?

Possible Duplicate:

Just Additional Info which took me long time to find.what if you were using the field name and not id for identifying the form field. You do it like this:

For radio button:

 var inp= $('input:radio[name=PatientPreviouslyReceivedDrug]:checked').val();

For textbox:

 var txt=$('input:text[name=DrugDurationLength]').val();

Remove scrollbars from textarea

I was able to get rid of my scroll bar on the body of text by removing my max-height attribute of my class.

How to center buttons in Twitter Bootstrap 3?

use text-align: center css property

Failed to find 'ANDROID_HOME' environment variable

April 11, 2019

None of the answers above solved my problem so I wanted to include a current solution (as of April 2019) for people using Ubuntu 18.04. This is how I solved the question above...

  1. I installed the Android SDK from the website, and put it in this folder: /usr/lib/Android/
  2. Search for where the SDK is installed and the version. In my case it was here:

    /usr/lib/Android/Sdk/build-tools/28.0.3

    Note: that I am using version 28.0.3, your version may differ.

  3. Add ANDROID_HOME to the environment path. To do this, open /etc/environment with a text editor:

    sudo nano /etc/environment

    Add a line for ANDROID_HOME for your specific version and path. In my case it was:

    ANDROID_HOME="/usr/lib/Android/Sdk/build-tools/28.0.3"

  4. Finally, source the updated environment with: source /etc/environment

    Confirm this by trying: echo $ANDROID_HOME in the terminal. You should get the path of your newly created variable.

    One additionally note about sourcing, I did have to restart my computer for the VScode terminal to recognize my changes. After the restart, the environment was set and I haven't had any issues since.

Secure FTP using Windows batch script

First, make sure you understand, if you need to use Secure FTP (=FTPS, as per your text) or SFTP (as per tag you have used).

Neither is supported by Windows command-line ftp.exe. As you have suggested, you can use WinSCP. It supports both FTPS and SFTP.

Using WinSCP, your batch file would look like (for SFTP):

echo open sftp://ftp_user:[email protected] -hostkey="server's hostkey" >> ftpcmd.dat
echo put c:\directory\%1-export-%date%.csv >> ftpcmd.dat
echo exit >> ftpcmd.dat
winscp.com /script=ftpcmd.dat
del ftpcmd.dat

And the batch file:

winscp.com /log=ftpcmd.log /script=ftpcmd.dat /parameter %1 %date%

Though using all capabilities of WinSCP (particularly providing commands directly on command-line and the %TIMESTAMP% syntax), the batch file simplifies to:

winscp.com /log=ftpcmd.log /command ^
    "open sftp://ftp_user:[email protected] -hostkey=""server's hostkey""" ^
    "put c:\directory\%1-export-%%TIMESTAMP#yyyymmdd%%.csv" ^
    "exit"

For the purpose of -hostkey switch, see verifying the host key in script.

Easier than assembling the script/batch file manually is to setup and test the connection settings in WinSCP GUI and then have it generate the script or batch file for you:

Generate batch file

All you need to tweak is the source file name (use the %TIMESTAMP% syntax as shown previously) and the path to the log file.


For FTPS, replace the sftp:// in the open command with ftpes:// (explicit TLS/SSL) or ftps:// (implicit TLS/SSL). Remove the -hostkey switch.

winscp.com /log=ftpcmd.log /command ^
    "open ftps://ftp_user:[email protected] -explicit" ^
    "put c:\directory\%1-export-%%TIMESTAMP#yyyymmdd%%.csv" ^
    "exit"

You may need to add the -certificate switch, if your server's certificate is not issued by a trusted authority.

Again, as with the SFTP, easier is to setup and test the connection settings in WinSCP GUI and then have it generate the script or batch file for you.


See a complete conversion guide from ftp.exe to WinSCP.

You should also read the Guide to automating file transfers to FTP server or SFTP server.


Note to using %TIMESTAMP#yyyymmdd% instead of %date%: A format of %date% variable value is locale-specific. So make sure you test the script on the same locale you are actually going to use the script on. For example on my Czech locale the %date% resolves to ct 06. 11. 2014, what might be problematic when used as a part of a file name.

For this reason WinSCP supports (locale-neutral) timestamp formatting natively. For example %TIMESTAMP#yyyymmdd% resolves to 20170515 on any locale.

(I'm the author of WinSCP)

How to find array / dictionary value using key?

It's as simple as this :

$array[$key];

How to overplot a line on a scatter plot in python?

A one-line version of this excellent answer to plot the line of best fit is:

plt.plot(np.unique(x), np.poly1d(np.polyfit(x, y, 1))(np.unique(x)))

Using np.unique(x) instead of x handles the case where x isn't sorted or has duplicate values.

The call to poly1d is an alternative to writing out m*x + b like in this other excellent answer.

Socket accept - "Too many open files"

This means that the maximum number of simultaneously open files.

Solved:

At the end of the file /etc/security/limits.conf you need to add the following lines:

* soft nofile 16384
* hard nofile 16384

In the current console from root (sudo does not work) to do:

ulimit -n 16384

Although this is optional, if it is possible to restart the server.

In /etc/nginx/nginx.conf file to register the new value worker_connections equal to 16384 divide by value worker_processes.

If not did ulimit -n 16384, need to reboot, then the problem will recede.

PS:

If after the repair is visible in the logs error accept() failed (24: Too many open files):

In the nginx configuration, propevia (for example):

worker_processes 2;

worker_rlimit_nofile 16384;

events {
  worker_connections 8192;
}

std::string formatting like sprintf

I gave it a try, with regular expressions. I implemented it for ints and const strings as an example, but you can add whatever other types (POD types but with pointers you can print anything).

#include <assert.h>
#include <cstdarg>

#include <string>
#include <sstream>
#include <regex>

static std::string
formatArg(std::string argDescr, va_list args) {
    std::stringstream ss;
    if (argDescr == "i") {
        int val = va_arg(args, int);
        ss << val;
        return ss.str();
    }
    if (argDescr == "s") {
        const char *val = va_arg(args, const char*);
        ss << val;
        return ss.str();
    }
    assert(0); //Not implemented
}

std::string format(std::string fmt, ...) {
    std::string result(fmt);
    va_list args;
    va_start(args, fmt);
    std::regex e("\\{([^\\{\\}]+)\\}");
    std::smatch m;
    while (std::regex_search(fmt, m, e)) {
        std::string formattedArg = formatArg(m[1].str(), args);
        fmt.replace(m.position(), m.length(), formattedArg);
    }
    va_end(args);
    return fmt;
}

Here is an example of use of it:

std::string formatted = format("I am {s} and I have {i} cats", "bob", 3);
std::cout << formatted << std::endl;

Output:

I am bob and I have 3 cats

How to scale an Image in ImageView to keep the aspect ratio

This worked for me:

android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxWidth="39dip"
android:scaleType="centerCrop"
android:adjustViewBounds ="true"

Is there a Public FTP server to test upload and download?

There's lots of FTP sites you can get into with the 'anonymous' account and download, but a 'public' site that allows anonymous uploads would be utterly swamped with pr0n and warez in short order.

It's easy enough to set up your own FTP server for testing uploads. There's plenty of them for most any desktop OS. There's one built into IIS, for instance.

How to convert SQL Server's timestamp column to datetime format

The simplest way of doing this is:

SELECT id,name,FROM_UNIXTIME(registration_date) FROM `tbl_registration`;

This gives the date column atleast in a readable format. Further if you want to change te format click here.

Can't find/install libXtst.so.6?

This worked for me in Luna elementary OS

sudo apt-get install libxtst6:i386

Difference Between Select and SelectMany

It's more clear when the query return a string (an array of char):

For example if the list 'Fruits' contains 'apple'

'Select' returns the string:

Fruits.Select(s=>s) 

[0]: "apple"

'SelectMany' flattens the string:

Fruits.SelectMany(s=>s)

[0]: 97  'a'
[1]: 112 'p'
[2]: 112 'p'
[3]: 108 'l'
[4]: 101 'e'

Difference between "and" and && in Ruby?

and has lower precedence than &&.

But for an unassuming user, problems might occur if it is used along with other operators whose precedence are in between, for example, the assignment operator:

def happy?() true; end
def know_it?() true; end

todo = happy? && know_it? ? "Clap your hands" : "Do Nothing"

todo
# => "Clap your hands"

todo = happy? and know_it? ? "Clap your hands" : "Do Nothing"

todo
# => true

How do I log errors and warnings into a file?

Take a look at the log_errors configuration option in php.ini. It seems to do just what you want to. I think you can use the error_log option to set your own logging file too.

When the log_errors directive is set to On, any errors reported by PHP would be logged to the server log or the file specified with error_log. You can set these options with ini_set too, if you need to.

(Please note that display_errors should be disabled in php.ini if this option is enabled)

The view or its master was not found or no view engine supports the searched locations

If the problem happens intermittently in production, it could be due to an action method getting interrupted. For example, during a POST operation involving a large file upload, the user closes the browser window before the upload completes. In this case, the action method may throw a null reference exception resulting from a null model or view object. A solution would be to wrap the method body in a try/catch and return null. Like this:

[HttpPost]
public ActionResult Post(...)
{
    try
    {
        ...
    }
    catch (NullReferenceException ex)  // could happen if POST is interrupted
    {
        // perhaps log a warning here
        return null;
    }

    return View(model);
}

ORA-01950: no privileges on tablespace 'USERS'

You cannot insert data because you have a quota of 0 on the tablespace. To fix this, run

ALTER USER <user> quota unlimited on <tablespace name>;

or

ALTER USER <user> quota 100M on <tablespace name>;

as a DBA user (depending on how much space you need / want to grant).

jQuery: Currency Format Number

$(document).ready(function() {
    var num = $('div.number').text()
    num = addPeriod(num);
    $('div.number').text('Rp. '+num)
});

function addPeriod(nStr)
{
    nStr += '';
    x = nStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, '$1' + '.' + '$2');
    }
    return x1 + x2;
}

Batch file to delete folders older than 10 days in Windows 7

If you want using it with parameter (ie. delete all subdirs under the given directory), then put this two lines into a *.bat or *.cmd file:

@echo off
for /f "delims=" %%d in ('dir %1 /s /b /ad ^| sort /r') do rd "%%d" 2>nul && echo rmdir %%d

and add script-path to your PATH environment variable. In this case you can call your batch file from any location (I suppose UNC path should work, too).

Eg.:

YourBatchFileName c:\temp

(you may use quotation marks if needed)

will remove all empty subdirs under c:\temp folder

YourBatchFileName

will remove all empty subdirs under the current directory.

How do you redirect to a page using the POST verb?

I would like to expand the answer of Jason Bunting

like this

ActionResult action = new SampelController().Index(2, "text");
return action;

And Eli will be here for something idea on how to make it generic variable

Can get all types of controller

How to send an email using PHP?

The native PHP function mail() does not work for me. It issues the message:

503 This mail server requires authentication when attempting to send to a non-local e-mail address

So, I usually use PHPMailer package

I've downloaded the version 5.2.23 from: GitHub.

I've just picked 2 files and put them in my source PHP root

class.phpmailer.php
class.smtp.php

In PHP, the file needs to be added

require_once('class.smtp.php');
require_once('class.phpmailer.php');

After this, it's just code:

require_once('class.smtp.php');
require_once('class.phpmailer.php');
... 
//----------------------------------------------
// Send an e-mail. Returns true if successful 
//
//   $to - destination
//   $nameto - destination name
//   $subject - e-mail subject
//   $message - HTML e-mail body
//   altmess - text alternative for HTML.
//----------------------------------------------
function sendmail($to,$nameto,$subject,$message,$altmess)  {

  $from  = "[email protected]";
  $namefrom = "yourname";
  $mail = new PHPMailer();  
  $mail->CharSet = 'UTF-8';
  $mail->isSMTP();   // by SMTP
  $mail->SMTPAuth   = true;   // user and password
  $mail->Host       = "localhost";
  $mail->Port       = 25;
  $mail->Username   = $from;  
  $mail->Password   = "yourpassword";
  $mail->SMTPSecure = "";    // options: 'ssl', 'tls' , ''  
  $mail->setFrom($from,$namefrom);   // From (origin)
  $mail->addCC($from,$namefrom);      // There is also addBCC
  $mail->Subject  = $subject;
  $mail->AltBody  = $altmess;
  $mail->Body = $message;
  $mail->isHTML();   // Set HTML type
//$mail->addAttachment("attachment");  
  $mail->addAddress($to, $nameto);
  return $mail->send();
}

It works like a charm