Programs & Examples On #Cffeed

Troubleshooting "Warning: session_start(): Cannot send session cache limiter - headers already sent"

Just replace session_start with this.

if (!session_id() && !headers_sent()) {
   session_start();
}  

You can put it anywhere, even at the end :) Works fine for me. $_SESSION is accessible as well.

"Connect failed: Access denied for user 'root'@'localhost' (using password: YES)" from php function

Try initializing your variables and use them in your connection object:

$username ="root";
$password = "password";
$host = "localhost";
$table = "shop";
$conn = new mysqli("$host", "$username", "$password", "$table");

How to delay the .keyup() handler until the user stops typing?

This is a solution along the lines of CMS's, but solves a few key issues for me:

  • Supports multiple inputs, delays can run concurrently.
  • Ignores key events that didn't changed the value (like Ctrl, Alt+Tab).
  • Solves a race condition (when the callback is executed and the value already changed).
var delay = (function() {
    var timer = {}
      , values = {}
    return function(el) {
        var id = el.form.id + '.' + el.name
        return {
            enqueue: function(ms, cb) {
                if (values[id] == el.value) return
                if (!el.value) return
                var original = values[id] = el.value
                clearTimeout(timer[id])
                timer[id] = setTimeout(function() {
                    if (original != el.value) return // solves race condition
                    cb.apply(el)
                }, ms)
            }
        }
    }
}())

Usage:

signup.key.addEventListener('keyup', function() {
    delay(this).enqueue(300, function() {
        console.log(this.value)
    })
})

The code is written in a style I enjoy, you may need to add a bunch of semicolons.

Things to keep in mind:

  • A unique id is generated based on the form id and input name, so they must be defined and unique, or you could adjust it to your situation.
  • delay returns an object that's easy to extend for your own needs.
  • The original element used for delay is bound to the callback, so this works as expected (like in the example).
  • Empty value is ignored in the second validation.
  • Watch out for enqueue, it expects milliseconds first, I prefer that, but you may want to switch the parameters to match setTimeout.

The solution I use adds another level of complexity, allowing you to cancel execution, for example, but this is a good base to build on.

Select all from table with Laravel and Eloquent

How to get all data from database to view using laravel, i hope this solution would be helpful for the beginners.

Inside your controller

public function get(){
        $types = select::all();
        return view('selectview')->with('types', $types);}

Import data model inside your controller, in my application the data model named as select.

use App\Select;

Inclusive of both my controller looks something like this

use App\Select;
class SelectController extends Controller{                             
    public function get(){
    $types = select::all();
    return view('selectview')->with('types', $types);}

select model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Select extends Model
{
    protected $fillable = [
        'name', 'email','phone','radio1','service',
    ];


    protected $table = 'selectdata';
    public $timestamps = false;
}

inside router

Route::get('/selectview', 'SelectController@get');

selectview.blade.php

@foreach($types as $type)
    <ul>
    <li>{{ $type->name }}</li>
    </ul>

    @endforeach

How can I mock requests and the response?

One possible way to work around requests is using the library betamax, it records all requests and after that if you make a request in the same url with the same parameters the betamax will use the recorded request, I have been using it to test web crawler and it save me a lot time.

import os

import requests
from betamax import Betamax
from betamax_serializers import pretty_json


WORKERS_DIR = os.path.dirname(os.path.abspath(__file__))
CASSETTES_DIR = os.path.join(WORKERS_DIR, u'resources', u'cassettes')
MATCH_REQUESTS_ON = [u'method', u'uri', u'path', u'query']

Betamax.register_serializer(pretty_json.PrettyJSONSerializer)
with Betamax.configure() as config:
    config.cassette_library_dir = CASSETTES_DIR
    config.default_cassette_options[u'serialize_with'] = u'prettyjson'
    config.default_cassette_options[u'match_requests_on'] = MATCH_REQUESTS_ON
    config.default_cassette_options[u'preserve_exact_body_bytes'] = True


class WorkerCertidaoTRT2:
    session = requests.session()

    def make_request(self, input_json):
        with Betamax(self.session) as vcr:
            vcr.use_cassette(u'google')
            response = session.get('http://www.google.com')

https://betamax.readthedocs.io/en/latest/

How to properly express JPQL "join fetch" with "where" clause as JPA 2 CriteriaQuery?

I will show visually the problem, using the great example from James answer and adding the alternative solution.

When you do the follow query, without the FETCH:

Select e from Employee e 
join e.phones p 
where p.areaCode = '613'

You will have the follow results from Employee as you expected:

EmployeeId EmployeeName PhoneId PhoneAreaCode
1 James 5 613
1 James 6 416

But when you add the FETCH word on JOIN, this is what happens:

EmployeeId EmployeeName PhoneId PhoneAreaCode
1 James 5 613

The generated SQL is the same for the two queries, but the Hibernate removes on memory the 416 register when you use WHERE on the FETCH join.

So, to bring all phones and apply the WHERE correctly, you need to have two JOINs: one for the WHERE and another for the FETCH. Like:

Select e from Employee e 
join e.phones p 
join fetch e.phones      //no alias, to not commit the mistake
where p.areaCode = '613'

Limit file format when using <input type="file">?

You can use "accept" attribute as a filter in the file select box. Using "accept" help you filter input files base on their "suffix" or their "meme type"

1.Filter based on suffix: Here "accept" attribute just allow to select files with .jpeg extension.

<input type="file" accept=".jpeg" />

2.Filter based on "file type" Here "accept" attribute just allow to select file with "image/jpeg" type.

<input type="file" accept="image/jpeg" />

Important: We can change or delete the extension of a file, without changing the meme type. For example it is possible to have a file without extension, but the type of this file can be "image/jpeg". So this file can not pass the accept=".jpeg" filter. but it can pass accept="image/jpeg".

3.We can use * to select all kind of a file type. For example below code allow to select all kind of images. for example "image/png" or "image/jpeg" or ... . All of them are allowed.

<input type="file" accept="image/*" /> 

4.We can use cama ( , ) as an "or operator" in select attribute. For example to allow all kind of images or pdf files we can use this code:

<input type="file" accept="image/* , application/pdf" />

How to draw a rectangle around a region of interest in python

As the other answers said, the function you need is cv2.rectangle(), but keep in mind that the coordinates for the bounding box vertices need to be integers if they are in a tuple, and they need to be in the order of (left, top) and (right, bottom). Or, equivalently, (xmin, ymin) and (xmax, ymax).

Facebook Graph API, how to get users email?

The only way to get the users e-mail address is to request extended permissions on the email field. The user must allow you to see this and you cannot get the e-mail addresses of the user's friends.

http://developers.facebook.com/docs/authentication/permissions

You can do this if you are using Facebook connect by passing scope=email in the get string of your call to the Auth Dialog.

I'd recommend using an SDK instead of file_get_contents as it makes it far easier to perform the Oauth authentication.

How to get controls in WPF to fill available space?

Each control deriving from Panel implements distinct layout logic performed in Measure() and Arrange():

  • Measure() determines the size of the panel and each of its children
  • Arrange() determines the rectangle where each control renders

The last child of the DockPanel fills the remaining space. You can disable this behavior by setting the LastChild property to false.

The StackPanel asks each child for its desired size and then stacks them. The stack panel calls Measure() on each child, with an available size of Infinity and then uses the child's desired size.

A Grid occupies all available space, however, it will set each child to their desired size and then center them in the cell.

You can implement your own layout logic by deriving from Panel and then overriding MeasureOverride() and ArrangeOverride().

See this article for a simple example.

Save the plots into a PDF

import datetime
import numpy as np
from matplotlib.backends.backend_pdf import PdfPages
import matplotlib.pyplot as plt

# Create the PdfPages object to which we will save the pages:
# The with statement makes sure that the PdfPages object is closed properly at
# the end of the block, even if an Exception occurs.
with PdfPages('multipage_pdf.pdf') as pdf:
    plt.figure(figsize=(3, 3))
    plt.plot(range(7), [3, 1, 4, 1, 5, 9, 2], 'r-o')
    plt.title('Page One')
    pdf.savefig()  # saves the current figure into a pdf page
    plt.close()

    plt.rc('text', usetex=True)
    plt.figure(figsize=(8, 6))
    x = np.arange(0, 5, 0.1)
    plt.plot(x, np.sin(x), 'b-')
    plt.title('Page Two')
    pdf.savefig()
    plt.close()

    plt.rc('text', usetex=False)
    fig = plt.figure(figsize=(4, 5))
    plt.plot(x, x*x, 'ko')
    plt.title('Page Three')
    pdf.savefig(fig)  # or you can pass a Figure object to pdf.savefig
    plt.close()

    # We can also set the file's metadata via the PdfPages object:
    d = pdf.infodict()
    d['Title'] = 'Multipage PDF Example'
    d['Author'] = u'Jouni K. Sepp\xe4nen'
    d['Subject'] = 'How to create a multipage pdf file and set its metadata'
    d['Keywords'] = 'PdfPages multipage keywords author title subject'
    d['CreationDate'] = datetime.datetime(2009, 11, 13)
    d['ModDate'] = datetime.datetime.today()

How to implement an android:background that doesn't stretch?

You can create an xml bitmap and use it as background for the view. To prevent stretching you can specify android:gravity attribute.

for example:

<?xml version="1.0" encoding="utf-8"?>
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/dvdr"
    android:tileMode="disabled" android:gravity="top" >
</bitmap>

There are a lot of options you can use to customize the rendering of the image

http://developer.android.com/guide/topics/resources/drawable-resource.html#Bitmap

Converting pfx to pem using openssl

Another perspective for doing it on Linux... here is how to do it so that the resulting single file contains the decrypted private key so that something like HAProxy can use it without prompting you for passphrase.

openssl pkcs12 -in file.pfx -out file.pem -nodes

Then you can configure HAProxy to use the file.pem file.


This is an EDIT from previous version where I had these multiple steps until I realized the -nodes option just simply bypasses the private key encryption. But I'm leaving it here as it may just help with teaching.

openssl pkcs12 -in file.pfx -out file.nokey.pem -nokeys
openssl pkcs12 -in file.pfx -out file.withkey.pem
openssl rsa -in file.withkey.pem -out file.key
cat file.nokey.pem file.key > file.combo.pem
  1. The 1st step prompts you for the password to open the PFX.
  2. The 2nd step prompts you for that plus also to make up a passphrase for the key.
  3. The 3rd step prompts you to enter the passphrase you just made up to store decrypted.
  4. The 4th puts it all together into 1 file.

Then you can configure HAProxy to use the file.combo.pem file.

The reason why you need 2 separate steps where you indicate a file with the key and another without the key, is because if you have a file which has both the encrypted and decrypted key, something like HAProxy still prompts you to type in the passphrase when it uses it.

How do I read a response from Python Requests?

If the response is in json you could do something like (python3):

import json
import requests as reqs

# Make the HTTP request.
response = reqs.get('http://demo.ckan.org/api/3/action/group_list')

# Use the json module to load CKAN's response into a dictionary.
response_dict = json.loads(response.text)

for i in response_dict:
    print("key: ", i, "val: ", response_dict[i])

To see everything in the response you can use .__dict__:

print(response.__dict__)

How can I create Min stl priority_queue?

We can do this using several ways.

Using template comparator parameter

    int main() 
    {
      priority_queue<int, vector<int>, greater<int> > pq;

      pq.push(40);
      pq.push(320);
      pq.push(42);
      pq.push(65);
      pq.push(12);

      cout<<pq.top()<<endl;
      return 0;
    }

Using used defined compartor class

     struct comp
     {
        bool operator () (int lhs, int rhs)
        {
           return lhs > rhs;
        }
     };

    int main()
    {
       priority_queue<int, vector<int>, comp> pq;

       pq.push(40);
       pq.push(320);
       pq.push(42);
       pq.push(65);
       pq.push(12);

       cout<<pq.top()<<endl;

       return 0;
    }

GetFiles with multiple extensions

The following retrieves the jpg, tiff and bmp files and gives you an IEnumerable<FileInfo> over which you can iterate:

var files = dinfo.GetFiles("*.jpg")
    .Concat(dinfo.GetFiles("*.tiff"))
    .Concat(dinfo.GetFiles("*.bmp"));

If you really need an array, simply stick .ToArray() at the end of this.

Capturing browser logs with Selenium WebDriver using Java

Add cast RemoteWebDriver to driver initialize and you will have the .setLogLevel method:

import java.util.logging.Level;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.remote.RemoteWebDriver;

public class PrintLogTest {
    public static void main(String[] args) {
        System.setProperty("webdriver.chrome.driver", "/Users/.../chromedriver");
        WebDriver driver = new ChromeDriver();

        //here
        ((RemoteWebDriver) driver).setLogLevel(Level.INFO);

        driver.get("https://google.com/");
        driver.findElement(By.name("q")).sendKeys("automation test");
        driver.quit();
    }
}

Example output:

Jun 15, 2020 4:27:04 PM org.openqa.selenium.remote.RemoteWebDriver log
INFO: Executing: get [430aec21a9beb6340a4185c4ea6a693d, get {url=https://google.com/}]
Jun 15, 2020 4:27:06 PM org.openqa.selenium.remote.RemoteWebDriver log
INFO: Executed: [430aec21a9beb6340a4185c4ea6a693d, get {url=https://google.com/}]
Jun 15, 2020 4:27:06 PM org.openqa.selenium.remote.RemoteWebDriver log
INFO: Executing: findElement [430aec21a9beb6340a4185c4ea6a693d, findElement {using=name, value=q}]
Jun 15, 2020 4:27:06 PM org.openqa.selenium.remote.RemoteWebDriver log
INFO: Executed: [430aec21a9beb6340a4185c4ea6a693d, findElement {using=name, value=q}]
...
...

At least I've tried it on ChromeDriver() and FirefoxDriver() and it working fine.

How to convert Varchar to Int in sql server 2008?

That is how you would do it, is it throwing an error? Are you sure the value you are trying to convert is convertible? For obvious reasons you cannot convert abc123 to an int.

UPDATE

Based on your comments I would remove any spaces that are in the values you are trying to convert.

Java HashMap: How to get a key and value by index?

for (Object key : data.keySet()) {
    String lKey = (String) key;
    List<String> list = data.get(key);
}

How to create custom config section in app.config?

Import namespace :

using System.Configuration;

Create ConfigurationElement Company :

public class Company : ConfigurationElement
{

        [ConfigurationProperty("name", IsRequired = true)]
        public string Name
        {
            get
            {
                return this["name"] as string;
            }
        }
            [ConfigurationProperty("code", IsRequired = true)]
        public string Code
        {
            get
            {
                return this["code"] as string;
            }
        }
}

ConfigurationElementCollection:

public class Companies
        : ConfigurationElementCollection
    {
        public Company this[int index]
        {
            get
            {
                return base.BaseGet(index) as Company ;
            }
            set
            {
                if (base.BaseGet(index) != null)
                {
                    base.BaseRemoveAt(index);
                }
                this.BaseAdd(index, value);
            }
        }

       public new Company this[string responseString]
       {
            get { return (Company) BaseGet(responseString); }
            set
            {
                if(BaseGet(responseString) != null)
                {
                    BaseRemoveAt(BaseIndexOf(BaseGet(responseString)));
                }
                BaseAdd(value);
            }
        }

        protected override System.Configuration.ConfigurationElement CreateNewElement()
        {
            return new Company();
        }

        protected override object GetElementKey(System.Configuration.ConfigurationElement element)
        {
            return ((Company)element).Name;
        }
    }

and ConfigurationSection:

public class RegisterCompaniesConfig
        : ConfigurationSection
    {

        public static RegisterCompaniesConfig GetConfig()
        {
            return (RegisterCompaniesConfig)System.Configuration.ConfigurationManager.GetSection("RegisterCompanies") ?? new RegisterCompaniesConfig();
        }

        [System.Configuration.ConfigurationProperty("Companies")]
            [ConfigurationCollection(typeof(Companies), AddItemName = "Company")]
        public Companies Companies
        {
            get
            {
                object o = this["Companies"];
                return o as Companies ;
            }
        }

    }

and you must also register your new configuration section in web.config (app.config):

<configuration>       
    <configSections>
          <section name="Companies" type="blablabla.RegisterCompaniesConfig" ..>

then you load your config with

var config = RegisterCompaniesConfig.GetConfig();
foreach(var item in config.Companies)
{
   do something ..
}

How to serve .html files with Spring

Java configuration for html files (in this case index.html):

@Configuration
@EnableWebMvc
public class DispatcherConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        registry.addResourceHandler("/index.html").addResourceLocations("/index.html");
    }

}

java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0 (unable to load class frontend.listener.StartupListener)

What is your output when you do java -version? This will tell you what version the running JVM is.

The Unsupported major.minor version 51.0 error could mean:

  • Your server is running a lower Java version then the one used to compile your Servlet and vice versa

Either way, uninstall all JVM runtimes including JDK and download latest and re-install. That should fix any Unsupported major.minor error as you will have the lastest JRE and JDK (Maybe even newer then the one used to compile the Servlet)

See: http://www.java.com/en/download/manual.jsp (7 Update 25 )

and here: http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform (JDK) 7u25)

for the latest version of the JRE and JDK respectively.

EDIT:

Most likely your code was written in Java7 however maybe it was done using Java7update4 and your system is running Java7update3. Thus they both are effectively the same major version but the minor versions differ. Only the larger minor version is backward compatible with the lower minor version.

Edit 2 : If you have more than one jdk installed on your pc. you should check that Apache Tomcat is using the same one (jre) you are compiling your programs with. If you installed a new jdk after installing apache it normally won't select the new version.

Connection timeout for SQL server

If you want to dynamically change it, I prefer using SqlConnectionStringBuilder .

It allows you to convert ConnectionString i.e. a string into class Object, All the connection string properties will become its Member.

In this case the real advantage would be that you don't have to worry about If the ConnectionTimeout string part is already exists in the connection string or not?

Also as it creates an Object and its always good to assign value in object rather than manipulating string.

Here is the code sample:

var sscsb = new SqlConnectionStringBuilder(_dbFactory.Database.ConnectionString);

sscsb.ConnectTimeout = 30;

var conn = new SqlConnection(sscsb.ConnectionString);

How do I use the Tensorboard callback of Keras?

This is how you use the TensorBoard callback:

from keras.callbacks import TensorBoard

tensorboard = TensorBoard(log_dir='./logs', histogram_freq=0,
                          write_graph=True, write_images=False)
# define model
model.fit(X_train, Y_train,
          batch_size=batch_size,
          epochs=nb_epoch,
          validation_data=(X_test, Y_test),
          shuffle=True,
          callbacks=[tensorboard])

ASP.NET Core return JSON with status code

This is my easiest solution:

public IActionResult InfoTag()
{
    return Ok(new {name = "Fabio", age = 42, gender = "M"});
}

or

public IActionResult InfoTag()
{
    return Json(new {name = "Fabio", age = 42, gender = "M"});
}

Change Date Format(DD/MM/YYYY) in SQL SELECT Statement

Changed to:

SELECT FORMAT(SA.[RequestStartDate],'dd/MM/yyyy') as 'Service Start Date', SA.[RequestEndDate] as 'Service End Date', FROM (......)SA WHERE......

Have no idea which SQL engine you are using, for other SQL engine, CONVERT can be used in SELECT statement to change the format in the form you needed.

How do I compute derivative using Numpy?

You have four options

  1. Finite Differences
  2. Automatic Derivatives
  3. Symbolic Differentiation
  4. Compute derivatives by hand.

Finite differences require no external tools but are prone to numerical error and, if you're in a multivariate situation, can take a while.

Symbolic differentiation is ideal if your problem is simple enough. Symbolic methods are getting quite robust these days. SymPy is an excellent project for this that integrates well with NumPy. Look at the autowrap or lambdify functions or check out Jensen's blogpost about a similar question.

Automatic derivatives are very cool, aren't prone to numeric errors, but do require some additional libraries (google for this, there are a few good options). This is the most robust but also the most sophisticated/difficult to set up choice. If you're fine restricting yourself to numpy syntax then Theano might be a good choice.

Here is an example using SymPy

In [1]: from sympy import *
In [2]: import numpy as np
In [3]: x = Symbol('x')
In [4]: y = x**2 + 1
In [5]: yprime = y.diff(x)
In [6]: yprime
Out[6]: 2·x

In [7]: f = lambdify(x, yprime, 'numpy')
In [8]: f(np.ones(5))
Out[8]: [ 2.  2.  2.  2.  2.]

How to export query result to csv in Oracle SQL Developer?

To take an export to your local system from sql developer.

Path : C:\Source_Table_Extract\des_loan_due_dtls_src_boaf.csv

    SPOOL "Path where you want to save the file"
    SELECT /*csv*/ * FROM TABLE_NAME;

How can I display an RTSP video stream in a web page?

One option would be to use some sort of streaming server/gateway. I tried various solutions (vlc, ffmpeg and a few more) and the one that worked best for me was Janus WebRTC server. It is somewhat difficult to set up, and you will have to compile it from source(when I tried it the version in Ubuntu repos didn't have RTSP support), but they have detailed compiling instructions and documentation on how to set everything up.

I managed to get video and audio feed from 3 FullHD cameras on local network with very little delay. I can confirm it works with Dahua and Hikvision cameras (not sure if all models).

What I used was Ubuntu Server 18.04 running Apache web server, and Chrome as a browser (it did not work on Firefox by default but perhaps there are workarounds for it).

LINQ: "contains" and a Lambda query

The Linq extension method Any could work for you...

buildingStatus.Any(item => item.GetCharValue() == v.Status)

Fastest way to check if a string is JSON in PHP?

I found this question after coming across something similar in my work, yesterday. My solution in the end was a hybrid of some of the approaches above:

function is_JSON($string) {

  return (is_null(json_decode($string, TRUE))) ? FALSE : TRUE;

}

How to take a screenshot programmatically on iOS

In Swift you can use following code.

if UIScreen.mainScreen().respondsToSelector(Selector("scale")) {
    UIGraphicsBeginImageContextWithOptions(self.window!.bounds.size, false, UIScreen.mainScreen().scale)
}
else{
    UIGraphicsBeginImageContext(self.window!.bounds.size)
}
self.window?.layer.renderInContext(UIGraphicsGetCurrentContext())
var image : UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)

IntelliJ IDEA 13 uses Java 1.5 despite setting to 1.7

One more thing that could cause this is having incorrect version of the <parent> project.

In my case it was pointing to a non-existing project and for some reason IntelliJ downgraded version in settings to 1.5 and later when I fixed it, it was still interpreting target code version as 5 (despite setting it to 11).

Where does Chrome store cookies?

Since the expiration time is zero (the third argument, the first false) the cookie is a session cookie, which will expire when the current session ends. (See the setcookie reference).

Therefore it doesn't need to be saved.

Setting Curl's Timeout in PHP

Hmm, it looks to me like CURLOPT_TIMEOUT defines the amount of time that any cURL function is allowed to take to execute. I think you should actually be looking at CURLOPT_CONNECTTIMEOUT instead, since that tells cURL the maximum amount of time to wait for the connection to complete.

jQuery: Check if button is clicked

jQuery(':button').click(function () {
    if (this.id == 'button1') {
        alert('Button 1 was clicked');
    }
    else if (this.id == 'button2') {
        alert('Button 2 was clicked');
    }
});

EDIT:- This will work for all buttons.

Compression/Decompression string with C#

This is an updated version for .NET 4.5 and newer using async/await and IEnumerables:

public static class CompressionExtensions
{
    public static async Task<IEnumerable<byte>> Zip(this object obj)
    {
        byte[] bytes = obj.Serialize();

        using (MemoryStream msi = new MemoryStream(bytes))
        using (MemoryStream mso = new MemoryStream())
        {
            using (var gs = new GZipStream(mso, CompressionMode.Compress))
                await msi.CopyToAsync(gs);

            return mso.ToArray().AsEnumerable();
        }
    }

    public static async Task<object> Unzip(this byte[] bytes)
    {
        using (MemoryStream msi = new MemoryStream(bytes))
        using (MemoryStream mso = new MemoryStream())
        {
            using (var gs = new GZipStream(msi, CompressionMode.Decompress))
            {
                // Sync example:
                //gs.CopyTo(mso);

                // Async way (take care of using async keyword on the method definition)
                await gs.CopyToAsync(mso);
            }

            return mso.ToArray().Deserialize();
        }
    }
}

public static class SerializerExtensions
{
    public static byte[] Serialize<T>(this T objectToWrite)
    {
        using (MemoryStream stream = new MemoryStream())
        {
            BinaryFormatter binaryFormatter = new BinaryFormatter();
            binaryFormatter.Serialize(stream, objectToWrite);

            return stream.GetBuffer();
        }
    }

    public static async Task<T> _Deserialize<T>(this byte[] arr)
    {
        using (MemoryStream stream = new MemoryStream())
        {
            BinaryFormatter binaryFormatter = new BinaryFormatter();
            await stream.WriteAsync(arr, 0, arr.Length);
            stream.Position = 0;

            return (T)binaryFormatter.Deserialize(stream);
        }
    }

    public static async Task<object> Deserialize(this byte[] arr)
    {
        object obj = await arr._Deserialize<object>();
        return obj;
    }
}

With this you can serialize everything BinaryFormatter supports, instead only of strings.

Edit:

In case, you need take care of Encoding, you could just use Convert.ToBase64String(byte[])...

Take a look at this answer if you need an example!

ArrayBuffer to base64 encoded string

function _arrayBufferToBase64(uarr) {
    var strings = [], chunksize = 0xffff;
    var len = uarr.length;

    for (var i = 0; i * chunksize < len; i++){
        strings.push(String.fromCharCode.apply(null, uarr.subarray(i * chunksize, (i + 1) * chunksize)));
    }

    return strings.join("");
}

This is better, if you use JSZip for unpack archive from string

How do I import an existing Java keystore (.jks) file into a Java installation?

Ok, so here was my process:

keytool -list -v -keystore permanent.jks - got me the alias.

keytool -export -alias alias_name -file certificate_name -keystore permanent.jks - got me the certificate to import.

Then I could import it with the keytool:

keytool -import -alias alias_name -file certificate_name -keystore keystore location

As @Christian Bongiorno says the alias can't already exist in your keystore.

Save ArrayList to SharedPreferences

All of the above answers are correct. :) I myself used one of these for my situation. However when I read the question I found that the OP is actually talking about a different scenario than the title of this post, if I didn't get it wrong.

"I need the array to stick around even if the user leaves the activity and then wants to come back at a later time"

He actually wants the data to be stored till the app is open, irrespective of user changing screens within the application.

"however I don't need the array available after the application has been closed completely"

But once the application is closed data should not be preserved.Hence I feel using SharedPreferences is not the optimal way for this.

What one can do for this requirement is create a class which extends Application class.

public class MyApp extends Application {

    //Pardon me for using global ;)

    private ArrayList<CustomObject> globalArray;

    public void setGlobalArrayOfCustomObjects(ArrayList<CustomObject> newArray){
        globalArray = newArray; 
    }

    public ArrayList<CustomObject> getGlobalArrayOfCustomObjects(){
        return globalArray;
    }

}

Using the setter and getter the ArrayList can be accessed from anywhere withing the Application. And the best part is once the app is closed, we do not have to worry about the data being stored. :)

const to Non-const Conversion in C++

You can assign a const object to a non-const object just fine. Because you're copying and thus creating a new object, constness is not violated.

Like so:

int main() {
   const int a = 3;
   int b = a;
}

It's different if you want to obtain a pointer or reference to the original, const object:

int main() {
   const int a = 3;
   int& b = a;       // or int* b = &a;
}

//  error: invalid initialization of reference of type 'int&' from
//         expression of type 'const int'

You can use const_cast to hack around the type safety if you really must, but recall that you're doing exactly that: getting rid of the type safety. It's still undefined to modify a through b in the below example:

int main() {
   const int a = 3;
   int& b = const_cast<int&>(a);

   b = 3;
}

Although it compiles without errors, anything can happen including opening a black hole or transferring all your hard-earned savings into my bank account.

If you have arrived at what you think is a requirement to do this, I'd urgently revisit your design because something is very wrong with it.

How to convert string date to Timestamp in java?

All you need to do is change the string within the java.text.SimpleDateFormat constructor to: "MM-dd-yyyy HH:mm:ss".

Just use the appropriate letters to build the above string to match your input date.

Chrome sendrequest error: TypeError: Converting circular structure to JSON

This works and tells you which properties are circular. It also allows for reconstructing the object with the references

  JSON.stringifyWithCircularRefs = (function() {
    const refs = new Map();
    const parents = [];
    const path = ["this"];

    function clear() {
      refs.clear();
      parents.length = 0;
      path.length = 1;
    }

    function updateParents(key, value) {
      var idx = parents.length - 1;
      var prev = parents[idx];
      if (prev[key] === value || idx === 0) {
        path.push(key);
        parents.push(value);
      } else {
        while (idx-- >= 0) {
          prev = parents[idx];
          if (prev[key] === value) {
            idx += 2;
            parents.length = idx;
            path.length = idx;
            --idx;
            parents[idx] = value;
            path[idx] = key;
            break;
          }
        }
      }
    }

    function checkCircular(key, value) {
      if (value != null) {
        if (typeof value === "object") {
          if (key) { updateParents(key, value); }

          let other = refs.get(value);
          if (other) {
            return '[Circular Reference]' + other;
          } else {
            refs.set(value, path.join('.'));
          }
        }
      }
      return value;
    }

    return function stringifyWithCircularRefs(obj, space) {
      try {
        parents.push(obj);
        return JSON.stringify(obj, checkCircular, space);
      } finally {
        clear();
      }
    }
  })();

Example with a lot of the noise removed:

{
    "requestStartTime": "2020-05-22...",
    "ws": {
        "_events": {},
        "readyState": 2,
        "_closeTimer": {
            "_idleTimeout": 30000,
            "_idlePrev": {
                "_idleNext": "[Circular Reference]this.ws._closeTimer",
                "_idlePrev": "[Circular Reference]this.ws._closeTimer",
                "expiry": 33764,
                "id": -9007199254740987,
                "msecs": 30000,
                "priorityQueuePosition": 2
            },
            "_idleNext": "[Circular Reference]this.ws._closeTimer._idlePrev",
            "_idleStart": 3764,
            "_destroyed": false
        },
        "_closeCode": 1006,
        "_extensions": {},
        "_receiver": {
            "_binaryType": "nodebuffer",
            "_extensions": "[Circular Reference]this.ws._extensions",
        },
        "_sender": {
            "_extensions": "[Circular Reference]this.ws._extensions",
            "_socket": {
                "_tlsOptions": {
                    "pipe": false,
                    "secureContext": {
                        "context": {},
                        "singleUse": true
                    },
                },
                "ssl": {
                    "_parent": {
                        "reading": true
                    },
                    "_secureContext": "[Circular Reference]this.ws._sender._socket._tlsOptions.secureContext",
                    "reading": true
                }
            },
            "_firstFragment": true,
            "_compress": false,
            "_bufferedBytes": 0,
            "_deflating": false,
            "_queue": []
        },
        "_socket": "[Circular Reference]this.ws._sender._socket"
    }
}

To reconstruct call JSON.parse() then loop through the properties looking for the [Circular Reference] tag. Then chop that off and... eval... it with this set to the root object.

Don't eval anything that can be hacked. Better practice would be to do string.split('.') then lookup the properties by name to set the reference.

MySQL Query GROUP BY day / month / year

try this one

SELECT COUNT(id)
FROM stats
GROUP BY EXTRACT(YEAR_MONTH FROM record_date)

EXTRACT(unit FROM date) function is better as less grouping is used and the function return a number value.

Comparison condition when grouping will be faster than DATE_FORMAT function (which return a string value). Try using function|field that return non-string value for SQL comparison condition (WHERE, HAVING, ORDER BY, GROUP BY).

Windows git "warning: LF will be replaced by CRLF", is that warning tail backward?

YES the warning is backwards.

And in fact it shouldn't even be a warning in the first place. Because all this warning is saying (but backwards unfortunately) is that the CRLF characters in your file with Windows line endings will be replaced with LF's on commit. Which means it's normalized to the same line endings used by *nix and MacOS.

Nothing strange is going on, this is exactly the behavior you would normally want.

This warning in it's current form is one of two things:

  1. An unfortunate bug combined with an over-cautious warning message, or
  2. A very clever plot to make you really think this through...

;)

Delete all documents from index/type without deleting type

I believe if you combine the delete by query with a match all it should do what you are looking for, something like this (using your example):

curl -XDELETE 'http://localhost:9200/twitter/tweet/_query' -d '{
    "query" : { 
        "match_all" : {}
    }
}'

Or you could just delete the type:

curl -XDELETE http://localhost:9200/twitter/tweet

How to simulate a click with JavaScript?

What about something simple like:

document.getElementById('elementID').click();

Supported even by IE.

Jquery Change Height based on Browser Size/Resize

$(function(){
    $(window).resize(function(){
        var h = $(window).height();
        var w = $(window).width();
        $("#elementToResize").css('height',(h < 768 || w < 1024) ? 500 : 400);
    });
});

Scrollbars etc have an effect on the window size so you may want to tweak to desired size.

Multiple github accounts on the same computer?

This answer is for beginners (none-git gurus). I recently had this problem and maybe its just me but most of the answers seemed to require rather advance understanding of git. After reading several stack overflow answers including this thread, here are the steps I needed to take in order to easily switch between GitHub accounts (e.g. assume two GitHub accounts, github.com/personal and gitHub.com/work):

  1. Check for existing ssh keys: Open Terminal and run this command to see/list existing ssh keys ls -al ~/.ssh
    files with extension .pub are your ssh keys so you should have two for the personal and work accounts. If there is only one or none, its time to generate other wise skip this.

    - Generating ssh key: login to github (either the personal or work acc.), navigate to Settings and copy the associated email.
    now go back to Terminal and run ssh-keygen -t rsa -C "the copied email", you'll see:

    Generating public/private rsa key pair.
    Enter file in which to save the key (/.../.ssh/id_rsa):


    id_rsa is the default name for the soon to be generated ssh key so copy the path and rename the default, e.g. /.../.ssh/id_rsa_work if generating for work account. provide a password or just enter to ignore and, you'll read something like The key's randomart image is: and the image. done.
    Repeat this step once more for your second github account. Make sure you use the right email address and a different ssh key name (e.g. id_rsa_personal) to avoid overwriting.
    At this stage, you should see two ssh keys when running ls -al ~/.ssh again.
  2. Associate ssh key with gitHub account: Next step is to copy one of the ssh keys, run this but replacing your own ssh key name: pbcopy < ~/.ssh/id_rsa_work.pub, replace id_rsa_work.pub with what you called yours.
    Now that our ssh key is copied to clipboard, go back to github account [Make sure you're logged in to work account if the ssh key you copied is id_rsa_work] and navigate to
    Settings - SSH and GPG Keys and click on New SSH key button (not New GPG key btw :D)
    give some title for this key, paste the key and click on Add SSH key. You've now either successfully added the ssh key or noticed it has been there all along which is fine (or you got an error because you selected New GPG key instead of New SSH key :D).
  3. Associate ssh key with gitHub account: Repeat the above step for your second account.
  4. Edit the global git configuration: Last step is to make sure the global configuration file is aware of all github accounts (so to say).
    Run git config --global --edit to edit this global file, if this opens vim and you don't know how to use it, press i to enter Insert mode, edit the file as below, and press esc followed by :wq to exit insert mode:

    [inside this square brackets give a name to the followed acc.] name = github_username email = github_emailaddress [any other name] name = github_username email = github_email [credential] helper = osxkeychain useHttpPath = true

Done!, now when trying to push or pull from a repo, you'll be asked which GitHub account should be linked with this repo and its asked only once, the local configuration will remember this link and not the global configuration so you can work on different repos that are linked with different accounts without having to edit global configuration each time.

Get the current user, within an ApiController action, without passing the userID as a parameter

You can also access the principal using the User property on ApiController.

So the following two statements are basically the same:

string id;
id = User.Identity.GetUserId();
id = RequestContext.Principal.Identity.GetUserId();

DELETE ... FROM ... WHERE ... IN

Try adding parentheses around the row in table1 e.g.

DELETE 
  FROM table1
 WHERE (stn, year(datum)) IN (SELECT stn, jaar FROM table2);

The above is Standard SQL-92 code. If that doesn't work, it could be that your SQL product of choice doesn't support it.

Here's another Standard SQL approach that is more widely implemented among vendors e.g. tested on SQL Server 2008:

MERGE INTO table1 AS t1
   USING table2 AS s1
      ON t1.stn = s1.stn
         AND s1.jaar = YEAR(t1.datum)
WHEN MATCHED THEN DELETE;

How to add number of days in postgresql datetime

This will give you the deadline :

select id,  
       title,
       created_at + interval '1' day * claim_window as deadline
from projects

Alternatively the function make_interval can be used:

select id,  
       title,
       created_at + make_interval(days => claim_window) as deadline
from projects

To get all projects where the deadline is over, use:

select *
from (
  select id, 
         created_at + interval '1' day * claim_window as deadline
  from projects
) t
where localtimestamp at time zone 'UTC' > deadline

How to make a Java Generic method static?

I'll explain it in a simple way.

Generics defined at Class level are completely separate from the generics defined at the (static) method level.

class Greet<T> {

    public static <T> void sayHello(T obj) {
        System.out.println("Hello " + obj);
    }
}

When you see the above code anywhere, please note that the T defined at the class level has nothing to do with the T defined in the static method. The following code is also completely valid and equivalent to the above code.

class Greet<T> {

    public static <E> void sayHello(E obj) {
        System.out.println("Hello " + obj);
    }
}

Why the static method needs to have its own generics separate from those of the Class?

This is because, the static method can be called without even instantiating the Class. So if the Class is not yet instantiated, we do not yet know what is T. This is the reason why the static methods needs to have its own generics.

So, whenever you are calling the static method,

Greet.sayHello("Bob");
Greet.sayHello(123);

JVM interprets it as the following.

Greet.<String>sayHello("Bob");
Greet.<Integer>sayHello(123);

Both giving the same outputs.

Hello Bob
Hello 123

javax.persistence.PersistenceException: No Persistence provider for EntityManager named customerManager

I was also facing the same issue when I was trying to get JPA entity manager configured in Tomcat 8. First I has an issue with the SystemException class not being found and hence the entityManagerFactory was not being created. I removed the hibernate entity manager dependency and then my entityManagerFactory was not able to lookup for the persistence provider. After going thru a lot of research and time got to know that hibernate entity manager is must to lookup for some configuration. Then put back the entity manager jar and then added JTA Api as a dependency and it worked fine.

How to parse JSON using Node.js?

My solution:

var fs = require('fs');
var file = __dirname + '/config.json';

fs.readFile(file, 'utf8', function (err, data) {
    if (err) {
        console.log('Error: ' + err);
        return;
    }

    data = JSON.parse(data);

    console.dir(data);
});

Pipenv: Command Not Found

OSX GUYS, OVER HERE!!!

As @charlax answered (for me the best one), you can use a more dynamic command to set PATH, buuut for mac users this could not work, sometimes your USER_BASE path got from site is wrong, so you need to find out where your python installation is.

$ which python3
/usr/local/bin/python3.6

you'll get a symlink, then you need to find the source's symlink.

$ ls -la /usr/local/bin/python3.6
  lrwxr-xr-x  1 root  wheel  71 Mar 14 17:56 /usr/local/bin/python3.6 -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6

(this ../../../ means root)

So you found the python path (/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6), then you just need to put in you ~/.bashrc as follows:

export PATH="$PATH:/Library/Frameworks/Python.framework/Versions/3.6/bin"

Convert serial.read() into a useable string using Arduino?

The best and most intuitive way is to use serialEvent() callback Arduino defines along with loop() and setup().

I've built a small library a while back that handles message reception, but never had time to opensource it. This library receives \n terminated lines that represent a command and arbitrary payload, space-separated. You can tweak it to use your own protocol easily.

First of all, a library, SerialReciever.h:

#ifndef __SERIAL_RECEIVER_H__
#define __SERIAL_RECEIVER_H__
    
class IncomingCommand {
  private:
    static boolean hasPayload;
  public:
    static String command;
    static String payload;
    static boolean isReady;
    static void reset() {
      isReady = false;
      hasPayload = false;
      command = "";
      payload = "";
    }
    static boolean append(char c) {
      if (c == '\n') {
        isReady = true;
        return true;
      }
      if (c == ' ' && !hasPayload) {
        hasPayload = true;
        return false;
      }
      if (hasPayload)
        payload += c;
      else
        command += c;
      return false;
    }
};
    
boolean IncomingCommand::isReady = false;
boolean IncomingCommand::hasPayload = false;
String IncomingCommand::command = false;
String IncomingCommand::payload = false;
    
#endif // #ifndef __SERIAL_RECEIVER_H__

To use it, in your project do this:

#include <SerialReceiver.h>
    
void setup() {
  Serial.begin(115200);
  IncomingCommand::reset();
}
    
void serialEvent() {
  while (Serial.available()) {
    char inChar = (char)Serial.read();
    if (IncomingCommand::append(inChar))
      return;
  }
}

To use the received commands:

void loop() {
  if (!IncomingCommand::isReady) {
    delay(10);
    return;
  }
executeCommand(IncomingCommand::command, IncomingCommand::payload); // I use registry pattern to handle commands, but you are free to do whatever suits your project better.
    
IncomingCommand::reset();

Create intermediate folders if one doesn't exist

You have to actually call some method to create the directories. Just creating a file object will not create the corresponding file or directory on the file system.

You can use File#mkdirs() method to create the directory: -

theFile.mkdirs();

Difference between File#mkdir() and File#mkdirs() is that, the later will create any intermediate directory if it does not exist.

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

Before You add Foreign key to the table, do the following

  1. Make sure the table must empty or The column data should match.
  2. Make sure it is not null.
  3. If the table contains do not go to design and change, do it manually.

    alter table Table 1 add foreign key (Column Name) references Table 2 (Column Name)

    alter table Table 1 alter column Column Name attribute not null

How to run server written in js with Node.js

I open a text editor, in my case I used Atom. Paste this code

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');

and save as

helloworld.js

in

c:\xampp\htdocs\myproject 

directory. Next I open node.js commamd prompt enter

cd c:\xampp\htdocs\myproject

next

node helloworld.js

next I open my chrome browser and I type

http://localhost:1337

and there it is.

Is there a destructor for Java?

Perhaps you can use a try ... finally block to finalize the object in the control flow at which you are using the object. Of course it doesn't happen automatically, but neither does destruction in C++. You often see closing of resources in the finally block.

HTML5 Dynamically create Canvas

 <html>
 <head></head>
 <body>
 <canvas id="canvas" width="300" height="300"></canvas>
 <script>
  var sun = new Image();
  var moon = new Image();
  var earth = new Image();
  function init() {
  sun.src = 'https://mdn.mozillademos.org/files/1456/Canvas_sun.png';
  moon.src = 'https://mdn.mozillademos.org/files/1443/Canvas_moon.png';
  earth.src = 'https://mdn.mozillademos.org/files/1429/Canvas_earth.png';
  window.requestAnimationFrame(draw);
  }

  function draw() {
  var ctx = document.getElementById('canvas').getContext('2d');

  ctx.globalCompositeOperation = 'destination-over';
  ctx.clearRect(0, 0, 300, 300);

  ctx.fillStyle = 'rgba(0, 0, 0, 0.4)';
  ctx.strokeStyle = 'rgba(0, 153, 255, 0.4)';
  ctx.save();
  ctx.translate(150, 150);

  // Earth
  var time = new Date();
  ctx.rotate(((2 * Math.PI) / 60) * time.getSeconds() + ((2 * Math.PI) / 60000) * 
  time.getMilliseconds());
  ctx.translate(105, 0);
  ctx.fillRect(10, -19, 55, 31); 
  ctx.drawImage(earth, -12, -12);

   // Moon
  ctx.save();
  ctx.rotate(((2 * Math.PI) / 6) * time.getSeconds() + ((2 * Math.PI) / 6000) * 
  time.getMilliseconds());
  ctx.translate(0, 28.5);
  ctx.drawImage(moon, -3.5, -3.5);
  ctx.restore();

  ctx.restore();

   ctx.beginPath();
   ctx.arc(150, 150, 105, 0, Math.PI * 2, false);
   ctx.stroke();

   ctx.drawImage(sun, 0, 0, 300, 300);

   window.requestAnimationFrame(draw);
    }

   init();
   </script>
   </body>
   </html>

Cannot bulk load because the file could not be opened. Operating System Error Code 3

I have solved this issue,

login to server computer where SQL Server is installed get you csv file on server computer and execute your query it will insert the records.

If you will give datatype compatibility issue change the datatype for that column

How to detect a loop in a linked list?

Algorithm

public static boolean hasCycle (LinkedList<Node> list)
{
    HashSet<Node> visited = new HashSet<Node>();

    for (Node n : list)
    {
        visited.add(n);

        if (visited.contains(n.next))
        {
            return true;
        }
    }

    return false;
}

Complexity

Time ~ O(n)
Space ~ O(n)

How to read a single character from the user?

The build-in raw_input should help.

for i in range(3):
    print ("So much work to do!")
k = raw_input("Press any key to continue...")
print ("Ok, back to work.")

SQL select everything in an array

SELECT * FROM products WHERE catid IN ('1', '2', '3', '4')

How to pass data to view in Laravel?

You can also pass an array as the second argument after the view template name, instead of stringing together a bunch of ->with() methods.

return View::make('blog', array('posts' => $posts));

Or, if you're using PHP 5.4 or better you can use the much nicer "short" array syntax:

return View::make('blog', ['posts' => $posts]);

This is useful if you want to compute the array elsewhere. For instance if you have a bunch of variables that every controller needs to pass to the view, and you want to combine this with an array of variables that is unique to each particular controller (using array_merge, for instance), you might compute $variables (which contains an array!):

return View::make('blog', $variables);

(I did this off the top of my head: let me know if a syntax error slipped in...)

FPDF error: Some data has already been output, can't send PDF

For fpdf to work properly, there cannot be any output at all beside what fpdf generates. For example, this will work:

<?php
$pdf = new FPDF();
$pdf->AddPage();
$pdf->SetFont('Arial','B',16);
$pdf->Cell(40,10,'Hello World!');
$pdf->Output();
?>

While this will not (note the leading space before the opening <? tag)

 <?php
$pdf = new FPDF();
$pdf->AddPage();
$pdf->SetFont('Arial','B',16);
$pdf->Cell(40,10,'Hello World!');
$pdf->Output();
?>

Also, this will not work either (the echo will break it):

<?php
echo "About to create pdf";
$pdf = new FPDF();
$pdf->AddPage();
$pdf->SetFont('Arial','B',16);
$pdf->Cell(40,10,'Hello World!');
$pdf->Output();
?>

I'm not sure about the drupal side of things, but I know that absolutely zero non-fpdf output is a requirement for fpdf to work.


add ob_start (); at the top and at the end add ob_end_flush();

<?php
    ob_start();
    require('fpdf.php');
    $pdf = new FPDF();
    $pdf->AddPage();
    $pdf->SetFont('Arial','B',16);
    $pdf->Cell(40,10,'Hello World!');
    $pdf->Output();
    ob_end_flush(); 
?>

give me an error as below:
FPDF error: Some data has already been output, can't send PDF

to over come this error: go to fpdf.php in that,goto line number 996

function Output($name='', $dest='')

after that make changes like this:

function Output($name='', $dest='') {   
    ob_clean();     //Output PDF to so

Hi do you have a session header on the top of your page. or any includes If you have then try to add this codes on top pf your page it should works fine.

<?

while (ob_get_level())
ob_end_clean();
header("Content-Encoding: None", true);

?>

cheers :-)


In my case i had set:

ini_set('display_errors', 'on');
error_reporting(E_ALL | E_STRICT);

When i made the request to generate the report, some warnings were displayed in the browser (like the usage of deprecated functions).
Turning off the display_errors option, the report was generated successfully.

How do I dump an object's fields to the console?

The to_yaml method seems to be useful sometimes:

$foo = {:name => "Clem", :age => 43}

puts $foo.to_yaml

returns

--- 
:age: 43
:name: Clem

(Does this depend on some YAML module being loaded? Or would that typically be available?)

Is there a no-duplicate List implementation out there?

So here's what I did eventually. I hope this helps someone else.

class NoDuplicatesList<E> extends LinkedList<E> {
    @Override
    public boolean add(E e) {
        if (this.contains(e)) {
            return false;
        }
        else {
            return super.add(e);
        }
    }

    @Override
    public boolean addAll(Collection<? extends E> collection) {
        Collection<E> copy = new LinkedList<E>(collection);
        copy.removeAll(this);
        return super.addAll(copy);
    }

    @Override
    public boolean addAll(int index, Collection<? extends E> collection) {
        Collection<E> copy = new LinkedList<E>(collection);
        copy.removeAll(this);
        return super.addAll(index, copy);
    }

    @Override
    public void add(int index, E element) {
        if (this.contains(element)) {
            return;
        }
        else {
            super.add(index, element);
        }
    }
}   

'import' and 'export' may only appear at the top level

I do not know how to solve this problem differently, but this is solved simply. The loader babel should be placed at the beginning of the array and everything works.

How to check if an item is selected from an HTML drop down list?

Select select = new Select(_element);
List<WebElement> selectedOptions = select.getAllSelectedOptions();

if(selectedOptions.size() > 0){
    return true;
}else{
    return false;
}

How can I directly view blobs in MySQL Workbench

had the same problem, according to the MySQL documentation, you can select a Substring of a BLOB:

SELECT id, SUBSTRING(comment,1,2000) FROM t

HTH, glissi

Getting value from JQUERY datepicker

You can use the getDate method:

var d = $('div#someID').datepicker('getDate');

That will give you a Date object in d.

There aren't any options for positioning the popup but you might be able to do something with CSS or the beforeShow event if necessary.

How do I clear/delete the current line in terminal?

Ctrl+A, Ctrl+K to wipe the current line in the terminal. You can then recall it with Ctrl+Y if you need.

What are Bearer Tokens and token_type in OAuth 2?

token_type is a parameter in Access Token generate call to Authorization server, which essentially represents how an access_token will be generated and presented for resource access calls. You provide token_type in the access token generation call to an authorization server.

If you choose Bearer (default on most implementation), an access_token is generated and sent back to you. Bearer can be simply understood as "give access to the bearer of this token." One valid token and no question asked. On the other hand, if you choose Mac and sign_type (default hmac-sha-1 on most implementation), the access token is generated and kept as secret in Key Manager as an attribute, and an encrypted secret is sent back as access_token.

Yes, you can use your own implementation of token_type, but that might not make much sense as developers will need to follow your process rather than standard implementations of OAuth.

How to clear/remove observable bindings in Knockout.js?

I had a memory leak problem recently and ko.cleanNode(element); wouldn't do it for me -ko.removeNode(element); did. Javascript + Knockout.js memory leak - How to make sure object is being destroyed?

Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='

A bit similar to @bpile answer, my case was a my.cnf entry setting collation-server = utf8_general_ci. After I realized that (and after trying everything above), I forcefully switched my database to utf8_general_ci instead of utf8_unicode_ci and that was it:

ALTER DATABASE `db` CHARACTER SET utf8 COLLATE utf8_general_ci;

Can I pass parameters in computed properties in Vue.Js

You can pass parameters but either it is not a vue.js way or the way you are doing is wrong.

However there are cases when you need to do so.I am going to show you a simple example passing value to computed property using getter and setter.

<template>
    <div>
        Your name is {{get_name}} <!-- John Doe at the beginning -->
        <button @click="name = 'Roland'">Change it</button>
    </div>
</template>

And the script

export default {
    data: () => ({
        name: 'John Doe'
    }),
    computed:{
        get_name: {
            get () {
                return this.name
            },
            set (new_name) {
                this.name = new_name
            }
        },
    }    
}

When the button clicked we are passing to computed property the name 'Roland' and in set() we are changing the name from 'John Doe' to 'Roland'.

Below there is a common use case when computed is used with getter and setter. Say you have the follow vuex store:

export default new Vuex.Store({
  state: {
    name: 'John Doe'
  },
  getters: {
    get_name: state => state.name
  },
  mutations: {
    set_name: (state, payload) => state.name = payload
  },
})

And in your component you want to add v-model to an input but using the vuex store.

<template>
    <div>
        <input type="text" v-model="get_name">
        {{get_name}}
    </div>
</template>
<script>
export default {
    computed:{
        get_name: {
            get () {
                return this.$store.getters.get_name
            },
            set (new_name) {
                this.$store.commit('set_name', new_name)
            }
        },
    }    
}
</script>

Replace characters from a column of a data frame R

Use gsub:

data1$c <- gsub('_', '-', data1$c)
data1

            a b   c
1  0.34597094 a A-B
2  0.92791908 b A-B
3  0.30168772 c A-B
4  0.46692738 d A-B
5  0.86853784 e A-C
6  0.11447618 f A-C
7  0.36508645 g A-C
8  0.09658292 h A-C
9  0.71661842 i A-C
10 0.20064575 j A-C

jQuery convert line breaks to br (nl2br equivalent)

you can simply do:

textAreaContent=textAreaContent.replace(/\n/g,"<br>");

How to copy static files to build directory with Webpack?

You can write bash in your package.json:

# package.json
{
  "name": ...,
  "version": ...,
  "scripts": {
    "build": "NODE_ENV=production npm run webpack && cp -v <this> <that> && echo ok",
    ...
  }
}

How do I get video durations with YouTube API version 3?

I got it!

$dur = file_get_contents("https://www.googleapis.com/youtube/v3/videos?part=contentDetails&id=$vId&key=dldfsd981asGhkxHxFf6JqyNrTqIeJ9sjMKFcX4");

$duration = json_decode($dur, true);
foreach ($duration['items'] as $vidTime) {
    $vTime= $vidTime['contentDetails']['duration'];
}

There it returns the time for YouTube API version 3 (the key is made up by the way ;). I used $vId that I had gotten off of the returned list of the videos from the channel I am showing the videos from...

It works. Google REALLY needs to include the duration in the snippet so you can get it all with one call instead of two... it's on their 'wontfix' list.

Access Enum value using EL with JSTL

Add a method to the enum like:

public String getString() {
    return this.name();
}

For example

public enum MyEnum {
    VALUE_1,
    VALUE_2;
    public String getString() {
        return this.name();
    }
}

Then you can use:

<c:if test="${myObject.myEnumProperty.string eq 'VALUE_2'}">...</c:if>

Triggering change detection manually in Angular

Try one of these:

  • ApplicationRef.tick() - similar to AngularJS's $rootScope.$digest() -- i.e., check the full component tree
  • NgZone.run(callback) - similar to $rootScope.$apply(callback) -- i.e., evaluate the callback function inside the Angular zone. I think, but I'm not sure, that this ends up checking the full component tree after executing the callback function.
  • ChangeDetectorRef.detectChanges() - similar to $scope.$digest() -- i.e., check only this component and its children

You can inject ApplicationRef, NgZone, or ChangeDetectorRef into your component.

How to set the default value of an attribute on a Laravel model

The other answers are not working for me - they may be outdated. This is what I used as my solution for auto setting an attribute:

/**
 * The "booting" method of the model.
 *
 * @return void
 */
protected static function boot()
{
    parent::boot();

    // auto-sets values on creation
    static::creating(function ($query) {
        $query->is_voicemail = $query->is_voicemail ?? true;
    });
}

How do I get the time difference between two DateTime objects using C#?

IF they are both UTC date-time values you can do TimeSpan diff = dateTime1 - dateTime2;

Otherwise your chance of getting the correct answer in every single possible case is zero.

index.php not loading by default

This one works like a charm!

First

<IfModule dir_module>
    DirectoryIndex index.html
     DirectoryIndex index.php
</IfModule>

then after that from

<Files ".ht*">
    Require all denied
</Files>

to

 <Files ".ht*">
    Require all granted
</Files>

C#: How to add subitems in ListView

Suppose you have a List Collection containing many items to show in a ListView, take the following example that iterates through the List Collection:

foreach (Inspection inspection in anInspector.getInspections())
  {
    ListViewItem item = new ListViewItem();
    item.Text=anInspector.getInspectorName().ToString();
    item.SubItems.Add(inspection.getInspectionDate().ToShortDateString());
    item.SubItems.Add(inspection.getHouse().getAddress().ToString());
    item.SubItems.Add(inspection.getHouse().getValue().ToString("C"));
    listView1.Items.Add(item);
  }

That code produces the following output in the ListView (of course depending how many items you have in the List Collection):

Basically the first column is a listviewitem containing many subitems (other columns). It may seem strange but listview is very flexible, you could even build a windows-like file explorer with it!

PHPExcel set border and format for all sheets in spreadsheet

To answer your extra question:

You can set which rows should be repeated on every page using:

$objPHPExcel->getActiveSheet()->getPageSetup()->setRowsToRepeatAtTopByStartAndEnd(1, 5);

Now, row 1, 2, 3, 4 and 5 will be repeated.

SQL update trigger only when column is modified

You want to do the following:

ALTER TRIGGER [dbo].[tr_SCHEDULE_Modified]
   ON [dbo].[SCHEDULE]
   AFTER UPDATE
AS 
BEGIN
SET NOCOUNT ON;

    IF (UPDATE(QtyToRepair))
    BEGIN
        UPDATE SCHEDULE SET modified = GETDATE()
            , ModifiedUser = SUSER_NAME()
            , ModifiedHost = HOST_NAME()
        FROM SCHEDULE S
        INNER JOIN Inserted I ON S.OrderNo = I.OrderNo AND S.PartNumber = I.PartNumber
        WHERE S.QtyToRepair <> I.QtyToRepair
    END
END

Please note that this trigger will fire each time you update the column no matter if the value is the same or not.

How to convert int to QString?

I always use QString::setNum().

int i = 10;
double d = 10.75;
QString str;
str.setNum(i);
str.setNum(d);

setNum() is overloaded in many ways. See QString class reference.

C char array initialization

This is not how you initialize an array, but for:

  1. The first declaration:

    char buf[10] = "";
    

    is equivalent to

    char buf[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    
  2. The second declaration:

    char buf[10] = " ";
    

    is equivalent to

    char buf[10] = {' ', 0, 0, 0, 0, 0, 0, 0, 0, 0};
    
  3. The third declaration:

    char buf[10] = "a";
    

    is equivalent to

    char buf[10] = {'a', 0, 0, 0, 0, 0, 0, 0, 0, 0};
    

As you can see, no random content: if there are fewer initializers, the remaining of the array is initialized with 0. This the case even if the array is declared inside a function.

Createuser: could not connect to database postgres: FATAL: role "tom" does not exist

sudo -u postgres createuser -s tom 

this should help you as this will happen if the administrator has not created a PostgreSQL user account for you. It could also be that you were assigned a PostgreSQL user name that is different from your operating system user name, in that case you need to use the -U switch.

Adding image to JFrame

Here is a simple example of adding an image to a JFrame:

frame.add(new JLabel(new ImageIcon("Path/To/Your/Image.png")));

Need help rounding to 2 decimal places

The System.Math.Round method uses the Double structure, which, as others have pointed out, is prone to floating point precision errors. The simple solution I found to this problem when I encountered it was to use the System.Decimal.Round method, which doesn't suffer from the same problem and doesn't require redifining your variables as decimals:

Decimal.Round(0.575, 2, MidpointRounding.AwayFromZero)

Result: 0.58

Making the main scrollbar always visible

Things have changed in the last years. The answers above are not valid in all cases any more. Apple is pushing disappearing scrollbars everywhere. Safari, Chrome and even Firefox on MacOs (and iOs) only show scrollbars when actually scrolling — I don't know about current Windows/IE. However there are non-standard ways to style scroll bars on Webkit (IE dropped that a long time ago).

Bootstrap - floating navbar button right

You would need to use the following markup. If you want to float any menu items to the right, create a separate <ul class="nav navbar-nav"> with navbar-right class to it.

_x000D_
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<html>_x000D_
_x000D_
<head>_x000D_
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>_x000D_
  <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />_x000D_
</head>_x000D_
_x000D_
<body>_x000D_
  <div class="navbar navbar-inverse navbar-fixed-top" role="navigation">_x000D_
    <div class="container">_x000D_
      <div class="navbar-header">_x000D_
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">_x000D_
            <span class="sr-only">Toggle navigation</span>_x000D_
            <span class="icon-bar"></span>_x000D_
            <span class="icon-bar"></span>_x000D_
            <span class="icon-bar"></span>_x000D_
          </button>_x000D_
        <a class="navbar-brand" href="#">Project name</a>_x000D_
      </div>_x000D_
      <div class="collapse navbar-collapse">_x000D_
        <ul class="nav navbar-nav">_x000D_
          <li class="active"><a href="#">Home</a></li>_x000D_
          <li><a href="#about">About</a></li>_x000D_
_x000D_
        </ul>_x000D_
        <ul class="nav navbar-nav navbar-right">_x000D_
          <li><a href="#contact">Contact</a></li>_x000D_
        </ul>_x000D_
      </div>_x000D_
    </div>_x000D_
  </div>_x000D_
</body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

ExecutorService that interrupts tasks after a timeout

Unfortunately the solution is flawed. There is a sort of bug with ScheduledThreadPoolExecutor, also reported in this question: cancelling a submitted task does not fully release the memory resources associated with the task; the resources are released only when the task expires.

If you therefore create a TimeoutThreadPoolExecutor with a fairly long expiration time (a typical usage), and submit tasks fast enough, you end up filling the memory - even though the tasks actually completed successfully.

You can see the problem with the following (very crude) test program:

public static void main(String[] args) throws InterruptedException {
    ExecutorService service = new TimeoutThreadPoolExecutor(1, 1, 10, TimeUnit.SECONDS, 
            new LinkedBlockingQueue<Runnable>(), 10, TimeUnit.MINUTES);
    //ExecutorService service = Executors.newFixedThreadPool(1);
    try {
        final AtomicInteger counter = new AtomicInteger();
        for (long i = 0; i < 10000000; i++) {
            service.submit(new Runnable() {
                @Override
                public void run() {
                    counter.incrementAndGet();
                }
            });
            if (i % 10000 == 0) {
                System.out.println(i + "/" + counter.get());
                while (i > counter.get()) {
                    Thread.sleep(10);
                }
            }
        }
    } finally {
        service.shutdown();
    }
}

The program exhausts the available memory, although it waits for the spawned Runnables to complete.

I though about this for a while, but unfortunately I could not come up with a good solution.

EDIT: I found out this issue was reported as JDK bug 6602600, and appears to have been fixed very recently.

How to execute shell command in Javascript

With nashorn you can write a script like this:

$EXEC('find -type f');
var files = $OUT.split('\n');
files.forEach(...
...

and run it:

jjs -scripting each_file.js

MySQL: can't access root account

There is a section in the MySQL manual on how to reset the root password which will solve your problem.

Removing duplicate rows from table in Oracle

5. solution

delete from emp where rowid in 
    (
      select  rid from
       (
         select rowid rid,rank() over (partition by emp_id order by rowid)rn from emp     
       )
     where rn > 1
    );

How do I create and read a value from cookie?

You can use my cookie ES module for get/set/remove cookie.

Usage:

In your head tag, include the following code:

<script src="https://raw.githack.com/anhr/cookieNodeJS/master/build/cookie.js"></script>

or

<script src="https://raw.githack.com/anhr/cookieNodeJS/master/build/cookie.min.js"></script>

Now you can use window.cookie for store user information in web pages.

cookie.isEnabled()

Is the cookie enabled in your web browser?

returns {boolean} true if cookie enabled.

Example

if ( cookie.isEnabled() )
    console.log('cookie is enabled on your browser');
else
    console.error('cookie is disabled on your browser');

cookie.set( name, value )

Set a cookie.

name: cookie name.
value: cookie value.

Example

cookie.set('age', 25);

cookie.get( name[, defaultValue] );

get a cookie.

name: cookie name.
defaultValue: cookie default value. Default is undefined.
returns cookie value or defaultValue if cookie was not found
Example
var age = cookie.get('age', 25);

cookie.remove( name );

Remove cookie.

name: cookie name.
Example
cookie.remove( 'age' );

Example of usage

Mac OS X - EnvironmentError: mysql_config not found

brew install mysql added mysql to /usr/local/Cellar/..., so I needed to add :/usr/local/Cellar/ to my $PATH and then which mysql_config worked!

How to send email from SQL Server?

To send mail through SQL Server we need to set up DB mail profile we can either use T-SQl or SQL Database mail option in sql server to create profile. After below code is used to send mail through query or stored procedure.

Use below link to create DB mail profile

http://www.freshcodehub.com/Article/42/configure-database-mail-in-sql-server-database

http://www.freshcodehub.com/Article/43/create-a-database-mail-configuration-using-t-sql-script

_x000D_
_x000D_
--Sending Test Mail_x000D_
EXEC msdb.dbo.sp_send_dbmail_x000D_
@profile_name = 'TestProfile', _x000D_
@recipients = 'To Email Here', _x000D_
@copy_recipients ='CC Email Here',             --For CC Email if exists_x000D_
@blind_copy_recipients= 'BCC Email Here',      --For BCC Email if exists_x000D_
@subject = 'Mail Subject Here', _x000D_
@body = 'Mail Body Here',_x000D_
@body_format='HTML',_x000D_
@importance ='HIGH',_x000D_
@file_attachments='C:\Test.pdf';               --For Attachments if exists
_x000D_
_x000D_
_x000D_

How to prevent going back to the previous activity?

There are two solutions for your case, activity A starts activity B, but you do not want to back to activity A in activity B.

1. Removed previous activity A from back stack.

    Intent intent = new Intent(activityA.this, activityB.class);
    startActivity(intent);
    finish(); // Destroy activity A and not exist in Back stack

2. Disabled go back button action in activity B.

There are two ways to prevent go back event as below,

1) Recommend approach

@Override
public void onBackPressed() {
}

2)Override onKeyDown method

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(keyCode==KeyEvent.KEYCODE_BACK) {
        return false;
    }
    return super.onKeyDown(keyCode, event);
}

Hope that it is useful, but still depends on your situations.

How can I remove the first line of a text file using bash/sed script?

Since it sounds like I can't speed up the deletion, I think a good approach might be to process the file in batches like this:

While file1 not empty
  file2 = head -n1000 file1
  process file2
  sed -i -e "1000d" file1
end

The drawback of this is that if the program gets killed in the middle (or if there's some bad sql in there - causing the "process" part to die or lock-up), there will be lines that are either skipped, or processed twice.

(file1 contains lines of sql code)

How to Export Private / Secret ASC Key to Decrypt GPG Files

Similar to @Wolfram J's answer, here is a method to encrypt your private key with a passphrase:

gpg --output - --armor --export $KEYID | \
    gpg --output private_key.asc --armor --symmetric --cipher-algo AES256

And a corresponding method to decrypt:

gpg private_key.asc

Angles between two n-dimensional vectors in Python

Note: all of the other answers here will fail if the two vectors have either the same direction (ex, (1, 0, 0), (1, 0, 0)) or opposite directions (ex, (-1, 0, 0), (1, 0, 0)).

Here is a function which will correctly handle these cases:

import numpy as np

def unit_vector(vector):
    """ Returns the unit vector of the vector.  """
    return vector / np.linalg.norm(vector)

def angle_between(v1, v2):
    """ Returns the angle in radians between vectors 'v1' and 'v2'::

            >>> angle_between((1, 0, 0), (0, 1, 0))
            1.5707963267948966
            >>> angle_between((1, 0, 0), (1, 0, 0))
            0.0
            >>> angle_between((1, 0, 0), (-1, 0, 0))
            3.141592653589793
    """
    v1_u = unit_vector(v1)
    v2_u = unit_vector(v2)
    return np.arccos(np.clip(np.dot(v1_u, v2_u), -1.0, 1.0))

How to get subarray from array?

The question is actually asking for a New array, so I believe a better solution would be to combine Abdennour TOUMI's answer with a clone function:

_x000D_
_x000D_
function clone(obj) {_x000D_
  if (null == obj || "object" != typeof obj) return obj;_x000D_
  const copy = obj.constructor();_x000D_
  for (const attr in obj) {_x000D_
    if (obj.hasOwnProperty(attr)) copy[attr] = obj[attr];_x000D_
  }_x000D_
  return copy;_x000D_
}_x000D_
_x000D_
// With the `clone()` function, you can now do the following:_x000D_
_x000D_
Array.prototype.subarray = function(start, end) {_x000D_
  if (!end) {_x000D_
    end = this.length;_x000D_
  } _x000D_
  const newArray = clone(this);_x000D_
  return newArray.slice(start, end);_x000D_
};_x000D_
_x000D_
// Without a copy you will lose your original array._x000D_
_x000D_
// **Example:**_x000D_
_x000D_
const array = [1, 2, 3, 4, 5];_x000D_
console.log(array.subarray(2)); // print the subarray [3, 4, 5, subarray: function]_x000D_
_x000D_
console.log(array); // print the original array [1, 2, 3, 4, 5, subarray: function]
_x000D_
_x000D_
_x000D_

[http://stackoverflow.com/questions/728360/most-elegant-way-to-clone-a-javascript-object]

What is Android keystore file, and what is it used for?

The whole idea of a keytool is to sign your apk with a unique identifier indicating the source of that apk. A keystore file (from what I understand) is used for debuging so your apk has the functionality of a keytool without signing your apk for production. So yes, for debugging purposes you should be able to sign multiple apk's with a single keystore. But understand that, upon pushing to production you'll need unique keytools as identifiers for each apk you create.

Is there a SELECT ... INTO OUTFILE equivalent in SQL Server Management Studio?

In SSMS, "Query" menu item... "Results to"... "Results to File"

Shortcut = CTRL+shift+F

You can set it globally too

"Tools"... "Options"... "Query Results"... "SQL Server".. "Default destination" drop down

Edit: after comment

In SSMS, "Query" menu item... "SQLCMD" mode

This allows you to run "command line" like actions.

A quick test in my SSMS 2008

:OUT c:\foo.txt
SELECT * FROM sys.objects

Edit, Sep 2012

:OUT c:\foo.txt
SET NOCOUNT ON;SELECT * FROM sys.objects

Difference between View and Request scope in managed beans

A @ViewScoped bean lives exactly as long as a JSF view. It usually starts with a fresh new GET request, or with a navigation action, and will then live as long as the enduser submits any POST form in the view to an action method which returns null or void (and thus navigates back to the same view). Once you refresh the page, or return a non-null string (even an empty string!) navigation outcome, then the view scope will end.

A @RequestScoped bean lives exactly as long a HTTP request. It will thus be garbaged by end of every request and recreated on every new request, hereby losing all changed properties.

A @ViewScoped bean is thus particularly more useful in rich Ajax-enabled views which needs to remember the (changed) view state across Ajax requests. A @RequestScoped one would be recreated on every Ajax request and thus fail to remember all changed view state. Note that a @ViewScoped bean does not share any data among different browser tabs/windows in the same session like as a @SessionScoped bean. Every view has its own unique @ViewScoped bean.

See also:

a page can have only one server-side form tag

It sounds like you have a form tag in a Master Page and in the Page that is throwing the error.

You can have only one.

Formatting MM/DD/YYYY dates in textbox in VBA

I never suggest using Textboxes or Inputboxes to accept dates. So many things can go wrong. I cannot even suggest using the Calendar Control or the Date Picker as for that you need to register the mscal.ocx or mscomct2.ocx and that is very painful as they are not freely distributable files.

Here is what I recommend. You can use this custom made calendar to accept dates from the user

PROS:

  1. You don't have to worry about user inputting wrong info
  2. You don't have to worry user pasting in the textbox
  3. You don't have to worry about writing any major code
  4. Attractive GUI
  5. Can be easily incorporated in your application
  6. Doesn't use any controls for which you need to reference any libraries like mscal.ocx or mscomct2.ocx

CONS:

Ummm...Ummm... Can't think of any...

HOW TO USE IT (File missing from my dropbox. Please refer to the bottom of the post for an upgraded version of the calendar)

  1. Download the Userform1.frm and Userform1.frx from here.
  2. In your VBA, simply import Userform1.frm as shown in the image below.

Importing the form

enter image description here

RUNNING IT

You can call it in any procedure. For example

Sub Sample()
    UserForm1.Show
End Sub

SCREEN SHOTS IN ACTION

enter image description here

NOTE: You may also want to see Taking Calendar to new level

JavaScript: changing the value of onclick with or without jQuery

If you don't want to actually navigate to a new page you can also have your anchor somewhere on the page like this.

<a id="the_anchor" href="">

And then to assign your string of JavaScript to the the onclick of the anchor, put this somewhere else (i.e. the header, later in the body, whatever):

<script>
    var js = "alert('I am your string of JavaScript');"; // js is your string of script
    document.getElementById('the_anchor').href = 'javascript:' + js;
</script>

If you have all of this info on the server before sending out the page, then you could also simply place the JavaScript directly in the href attribute of the anchor like so:

<a href="javascript:alert('I am your script.'); alert('So am I.');">Click me</a>

What does java.lang.Thread.interrupt() do?

Thread.interrupt() sets the interrupted status/flag of the target thread. Then code running in that target thread MAY poll the interrupted status and handle it appropriately. Some methods that block such as Object.wait() may consume the interrupted status immediately and throw an appropriate exception (usually InterruptedException)

Interruption in Java is not pre-emptive. Put another way both threads have to cooperate in order to process the interrupt properly. If the target thread does not poll the interrupted status the interrupt is effectively ignored.

Polling occurs via the Thread.interrupted() method which returns the current thread's interrupted status AND clears that interrupt flag. Usually the thread might then do something such as throw InterruptedException.

EDIT (from Thilo comments): Some API methods have built in interrupt handling. Of the top of my head this includes.

  • Object.wait(), Thread.sleep(), and Thread.join()
  • Most java.util.concurrent structures
  • Java NIO (but not java.io) and it does NOT use InterruptedException, instead using ClosedByInterruptException.

EDIT (from @thomas-pornin's answer to exactly same question for completeness)

Thread interruption is a gentle way to nudge a thread. It is used to give threads a chance to exit cleanly, as opposed to Thread.stop() that is more like shooting the thread with an assault rifle.

how to use DEXtoJar

  1. Download latest dex2jar from here -> dex2jar
  2. Run this command on linux -> sh d2j-dex2jar.sh classes.dex
  3. Download java decompiler from here - > JD-GUI
  4. Drag and drop the classes-dex2jar.jar file to JD-GUI

How to transform array to comma separated words string?

Make your array a variable and use implode.

$array = array('lastname', 'email', 'phone');
$comma_separated = implode(",", $array);

echo $comma_separated; // lastname,email,phone

http://php.net/manual/en/function.implode.php

Dynamically load a JavaScript file

Here is a simple one with callback and IE support:

function loadScript(url, callback) {

    var script = document.createElement("script")
    script.type = "text/javascript";

    if (script.readyState) { //IE
        script.onreadystatechange = function () {
            if (script.readyState == "loaded" || script.readyState == "complete") {
                script.onreadystatechange = null;
                callback();
            }
        };
    } else { //Others
        script.onload = function () {
            callback();
        };
    }

    script.src = url;
    document.getElementsByTagName("head")[0].appendChild(script);
}

loadScript("https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js", function () {

     //jQuery loaded
     console.log('jquery loaded');

});

Getting strings recognized as variable names in R

The basic answer to the question in the title is eval(as.symbol(variable_name_as_string)) as Josh O'Brien uses. e.g.

var.name = "x"
assign(var.name, 5)
eval(as.symbol(var.name)) # outputs 5

Or more simply:

get(var.name) # 5

Why do you use typedef when declaring an enum in C++?

In some C codestyle guide the typedef version is said to be preferred for "clarity" and "simplicity". I disagree, because the typedef obfuscates the real nature of the declared object. In fact, I don't use typedefs because when declaring a C variable I want to be clear about what the object actually is. This choice helps myself to remember faster what an old piece of code actually does, and will help others when maintaining the code in the future.

How to filter a dictionary according to an arbitrary condition function?

dict((k, v) for (k, v) in points.iteritems() if v[0] < 5 and v[1] < 5)

Syntax error: Illegal return statement in JavaScript

return only makes sense inside a function. There is no function in your code.

Also, your code is worthy if the Department of Redundancy Department. Assuming you move it to a proper function, this would be better:

return confirm(".json_encode($message).");

EDIT much much later: Changed code to use json_encode to ensure the message contents don't break just because of an apostrophe in the message.

C# create simple xml file

I'd recommend serialization,

public class Person
{
      public  string FirstName;
      public  string MI;
      public  string LastName;
}

static void Serialize()
{
      clsPerson p = new Person();
      p.FirstName = "Jeff";
      p.MI = "A";
      p.LastName = "Price";
      System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(p.GetType());
      x.Serialize(System.Console.Out, p);
      System.Console.WriteLine();
      System.Console.WriteLine(" --- Press any key to continue --- ");
      System.Console.ReadKey();
}

You can further control serialization with attributes.
But if it is simple, you could use XmlDocument:

using System;
using System.Xml;

public class GenerateXml {
    private static void Main() {
        XmlDocument doc = new XmlDocument();
        XmlNode docNode = doc.CreateXmlDeclaration("1.0", "UTF-8", null);
        doc.AppendChild(docNode);

        XmlNode productsNode = doc.CreateElement("products");
        doc.AppendChild(productsNode);

        XmlNode productNode = doc.CreateElement("product");
        XmlAttribute productAttribute = doc.CreateAttribute("id");
        productAttribute.Value = "01";
        productNode.Attributes.Append(productAttribute);
        productsNode.AppendChild(productNode);

        XmlNode nameNode = doc.CreateElement("Name");
        nameNode.AppendChild(doc.CreateTextNode("Java"));
        productNode.AppendChild(nameNode);
        XmlNode priceNode = doc.CreateElement("Price");
        priceNode.AppendChild(doc.CreateTextNode("Free"));
        productNode.AppendChild(priceNode);

        // Create and add another product node.
        productNode = doc.CreateElement("product");
        productAttribute = doc.CreateAttribute("id");
        productAttribute.Value = "02";
        productNode.Attributes.Append(productAttribute);
        productsNode.AppendChild(productNode);
        nameNode = doc.CreateElement("Name");
        nameNode.AppendChild(doc.CreateTextNode("C#"));
        productNode.AppendChild(nameNode);
        priceNode = doc.CreateElement("Price");
        priceNode.AppendChild(doc.CreateTextNode("Free"));
        productNode.AppendChild(priceNode);

        doc.Save(Console.Out);
    }
}

And if it needs to be fast, use XmlWriter:

public static void WriteXML()
{
    // Create an XmlWriterSettings object with the correct options.
    System.Xml.XmlWriterSettings settings = new System.Xml.XmlWriterSettings();
    settings.Indent = true;
    settings.IndentChars = "    "; //  "\t";
    settings.OmitXmlDeclaration = false;
    settings.Encoding = System.Text.Encoding.UTF8;

    using (System.Xml.XmlWriter writer = System.Xml.XmlWriter.Create("data.xml", settings))
    {

        writer.WriteStartDocument();
        writer.WriteStartElement("books");

        for (int i = 0; i < 100; ++i)
        {
            writer.WriteStartElement("book");
            writer.WriteElementString("item", "Book "+ (i+1).ToString());
            writer.WriteEndElement();
        }

        writer.WriteEndElement();

        writer.Flush();
        writer.Close();
    } // End Using writer 

}

And btw, the fastest way to read XML is XmlReader:

public static void ReadXML()
{
    using (System.Xml.XmlReader xmlReader = System.Xml.XmlReader.Create("http://www.ecb.int/stats/eurofxref/eurofxref-daily.xml"))
    {
        while (xmlReader.Read())
        {
            if ((xmlReader.NodeType == System.Xml.XmlNodeType.Element) && (xmlReader.Name == "Cube"))
            {
                if (xmlReader.HasAttributes)
                    System.Console.WriteLine(xmlReader.GetAttribute("currency") + ": " + xmlReader.GetAttribute("rate"));
            }

        } // Whend 

    } // End Using xmlReader

    System.Console.ReadKey();
}

And the most convenient way to read XML is to just deserialize the XML into a class.
This also works for creating the serialization classes, btw.
You can generate the class from XML with Xml2CSharp:
https://xmltocsharp.azurewebsites.net/

Timer Interval 1000 != 1 second?

Instead of Tick event, use Elapsed event.

timer.Elapsed += new EventHandler(TimerEventProcessor);

and change the signiture of TimerEventProcessor method;

private void TimerEventProcessor(object sender, ElapsedEventArgs e)
{
  label1.Text = _counter.ToString();
  _counter += 1;
}

How to access the contents of a vector from a pointer to the vector in C++?

vector <int> numbers {10,20,30,40};
vector <int> *ptr {nullptr};

ptr = &numbers;

for(auto num: *ptr){
 cout << num << endl;
}


cout << (*ptr).at(2) << endl; // 20

cout << "-------" << endl;

cout << ptr -> at(2) << endl; // 20

iPhone - Get Position of UIView within entire UIWindow

Swift 3, with extension:

extension UIView{
    var globalPoint :CGPoint? {
        return self.superview?.convert(self.frame.origin, to: nil)
    }

    var globalFrame :CGRect? {
        return self.superview?.convert(self.frame, to: nil)
    }
}

How to enable/disable bluetooth programmatically in android

The solution of prijin worked perfectly for me. It is just fair to mention that two additional permissions are needed:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

When these are added, enabling and disabling works flawless with the default bluetooth adapter.

Prevent nginx 504 Gateway timeout using PHP set_time_limit()

You need to add extra nginx directive (for ngx_http_proxy_module) in nginx.conf, e.g.:

proxy_read_timeout 300;

Basically the nginx proxy_read_timeout directive changes the proxy timeout, the FcgidIOTimeout is for scripts that are quiet too long, and FcgidBusyTimeout is for scripts that take too long to execute.

Also if you're using FastCGI application, increase these options as well:

FcgidBusyTimeout 300
FcgidIOTimeout 250

Then reload nginx and PHP5-FPM.

Plesk

In Plesk, you can add it in Web Server Settings under Additional nginx directives.

For FastCGI check in Web Server Settings under Additional directives for HTTP.

See: How to fix FastCGI timeout issues in Plesk?

Daylight saving time and time zone best practices

While I haven't tried it, an approach to time zone adjustments I would find compelling would be as follows:

  1. Store everything in UTC.

  2. Create a table TZOffsets with three columns: RegionClassId, StartDateTime, and OffsetMinutes (int, in minutes).

In the table, store a list of dates and times when the local time changed, and by how much. The number of regions in the table and the number of dates would depend on what range of dates and areas of the world you need to support. Think of this as if it is "historical" date, even though the dates should include the future to some practical limit.

When you need to compute the local time of any UTC time, just do this:

SELECT DATEADD('m', SUM(OffsetMinutes), @inputdatetime) AS LocalDateTime
FROM   TZOffsets
WHERE  StartDateTime <= @inputdatetime
       AND RegionClassId = @RegionClassId;

You might want to cache this table in your app and use LINQ or some similar means to do the queries rather than hitting the database.

This data can be distilled from the public domain tz database.

Advantages and footnotes of this approach:

  1. No rules are baked into code, you can adjust the offsets for new regions or date ranges readily.
  2. You don't have to support every range of dates or regions, you can add them as needed.
  3. Regions don't have to correspond directly to geopolitical boundaries, and to avoid duplication of rows (for instance, most states in the US handle DST the same way), you can have broad RegionClass entries that link in another table to more traditional lists of states, countries, etc.
  4. For situations like the US where the start and end date of DST has changed over the past few years, this is pretty easy to deal with.
  5. Since the StartDateTime field can store a time as well, the 2:00 AM standard change-over time is handled easily.
  6. Not everywhere in the world uses a 1-hour DST. This handles those cases easily.
  7. The data table is cross-platform and could be a separate open-source project that could be used by developers who use nearly any database platform or programming language.
  8. This can be used for offsets that have nothing to do with time zones. For instance, the 1-second adjustments that happen from time to time to adjust for the Earth's rotation, historical adjustments to and within the Gregorian calendar, etc.
  9. Since this is in a database table, standard report queries, etc. can take advantage of the data without a trip through business logic code.
  10. This handles time zone offsets as well if you want it to, and can even account for special historical cases where a region is assigned to another time zone. All you need is an initial date that assigns a time zone offset to each region with a minimal start date. This would require creating at least one region for each time zone, but would allow you to ask interesting questions like: "What is the difference in local time between Yuma, Arizona and Seattle, Washington on February 2, 1989 at 5:00am?" (Just subtract one SUM() from the other).

Now, the only disadvantage of this approach or any other is that conversions from local time to GMT are not perfect, since any DST change that has a negative offset to the clock repeats a given local time. No easy way to deal with that one, I'm afraid, which is one reason storing local times is bad news in the first place.

Android Spinner : Avoid onItemSelected calls during initialization

The user interaction flag can then be set to true in the onTouch method and reset in onItemSelected() once the selection change has been handled. I prefer this solution because the user interaction flag is handled exclusively for the spinner, and not for other views in the activity that may affect the desired behavior.

In code:

Create your listener for the spinner:

public class SpinnerInteractionListener implements AdapterView.OnItemSelectedListener, View.OnTouchListener {

    boolean userSelect = false;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        userSelect = true;
        return false;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
        if (userSelect) { 
            userSelect = false;
            // Your selection handling code here
        }
    }

}

Add the listener to the spinner as both an OnItemSelectedListener and an OnTouchListener:

SpinnerInteractionListener listener = new SpinnerInteractionListener();
mSpinnerView.setOnTouchListener(listener);
mSpinnerView.setOnItemSelectedListener(listener);

How to put wildcard entry into /etc/hosts?

It happens that /etc/hosts file doesn't support wild card entries.

You'll have to use other services like dnsmasq. To enable it in dnsmasq, just edit dnsmasq.conf and add the following line:

address=/example.com/127.0.0.1

Converting unix timestamp string to readable date

>>> import time
>>> time.ctime(int("1284101485"))
'Fri Sep 10 16:51:25 2010'
>>> time.strftime("%D %H:%M", time.localtime(int("1284101485")))
'09/10/10 16:51'

Create an array of strings

Another option:

names = repmat({'Sample Text'}, 10, 1)

Using `date` command to get previous, current and next month

The problem is that date takes your request quite literally and tries to use a date of 31st September (being 31st October minus one month) and then because that doesn't exist it moves to the next day which does. The date documentation (from info date) has the following advice:

The fuzz in units can cause problems with relative items. For example, `2003-07-31 -1 month' might evaluate to 2003-07-01, because 2003-06-31 is an invalid date. To determine the previous month more reliably, you can ask for the month before the 15th of the current month. For example:

 $ date -R
 Thu, 31 Jul 2003 13:02:39 -0700
 $ date --date='-1 month' +'Last month was %B?'
 Last month was July?
 $ date --date="$(date +%Y-%m-15) -1 month" +'Last month was %B!'
 Last month was June!

How to use HttpWebRequest (.NET) asynchronously?

Considering the answer:

HttpWebRequest webRequest;

void StartWebRequest()
{
    webRequest.BeginGetResponse(new AsyncCallback(FinishWebRequest), null);
}

void FinishWebRequest(IAsyncResult result)
{
    webRequest.EndGetResponse(result);
}

You could send the request pointer or any other object like this:

void StartWebRequest()
{
    HttpWebRequest webRequest = ...;
    webRequest.BeginGetResponse(new AsyncCallback(FinishWebRequest), webRequest);
}

void FinishWebRequest(IAsyncResult result)
{
    HttpWebResponse response = (result.AsyncState as HttpWebRequest).EndGetResponse(result) as HttpWebResponse;
}

Greetings

Setting width and height

In my case, passing responsive: false under options solved the problem. I'm not sure why everybody is telling you to do the opposite, especially since true is the default.

PostgreSQL: FOREIGN KEY/ON DELETE CASCADE

A foreign key with a cascade delete means that if a record in the parent table is deleted, then the corresponding records in the child table will automatically be deleted. This is called a cascade delete.

You are saying in a opposite way, this is not that when you delete from child table then records will be deleted from parent table.

UPDATE 1:

ON DELETE CASCADE option is to specify whether you want rows deleted in a child table when corresponding rows are deleted in the parent table. If you do not specify cascading deletes, the default behaviour of the database server prevents you from deleting data in a table if other tables reference it.

If you specify this option, later when you delete a row in the parent table, the database server also deletes any rows associated with that row (foreign keys) in a child table. The principal advantage to the cascading-deletes feature is that it allows you to reduce the quantity of SQL statements you need to perform delete actions.

So it's all about what will happen when you delete rows from Parent table not from child table.

So in your case when user removes entries from CATs table then rows will be deleted from books table. :)

Hope this helps you :)

How to implode array with key and value without foreach in PHP

For debugging purposes. Recursive write an array of nested arrays to a string. Used foreach. Function stores National Language characters.

function q($input)
{
    $glue = ', ';
    $function = function ($v, $k) use (&$function, $glue) {
        if (is_array($v)) {
            $arr = [];
            foreach ($v as $key => $value) {
                $arr[] = $function($value, $key);
            }
            $result = "{" . implode($glue, $arr) . "}";
        } else {
            $result = sprintf("%s=\"%s\"", $k, var_export($v, true));
        }
        return $result;
    };
    return implode($glue, array_map($function, $input, array_keys($input))) . "\n";
}

Why does the jquery change event not trigger when I set the value of a select using val()?

Adding this piece of code after the val() seems to work:

$(":input#single").trigger('change');

You don't have permission to access / on this server

Fist check that apache is running. service httpd restart for restarting

CentOS 6 comes with SELinux activated, so, either change the policy or disabled it by editing /etc/sysconfig/selinux setting SELINUX=disabled. Then restart

Then check locally (from centos) if apache is working.

split string in two on given index and return both parts

Something like this?...

 function stringConverter(varString, varCommaPosition)
 {
   var stringArray = varString.split("");
   var outputString = '';
   for(var i=0;i<stringArray.length;i++)
   {
     if(i == varCommaPosition)
      {
        outputString = outputString + ',';
      }

     outputString = outputString + stringArray[i];
   }  

   return outputString;
 }

Creating a REST API using PHP

Trying to write a REST API from scratch is not a simple task. There are many issues to factor and you will need to write a lot of code to process requests and data coming from the caller, authentication, retrieval of data and sending back responses.

Your best bet is to use a framework that already has this functionality ready and tested for you.

Some suggestions are:

Phalcon - REST API building - Easy to use all in one framework with huge performance

Apigility - A one size fits all API handling framework by Zend Technologies

Laravel API Building Tutorial

and many more. Simple searches on Bitbucket/Github will give you a lot of resources to start with.

CSS transition with visibility not working

Visibility is an animatable property according to the spec, but transitions on visibility do not work gradually, as one might expect. Instead transitions on visibility delay hiding an element. On the other hand making an element visible works immediately. This is as it is defined by the spec (in the case of the default timing function) and as it is implemented in the browsers.

This also is a useful behavior, since in fact one can imagine various visual effects to hide an element. Fading out an element is just one kind of visual effect that is specified using opacity. Other visual effects might move away the element using e.g. the transform property, also see http://taccgl.org/blog/css-transition-visibility.html

It is often useful to combine the opacity transition with a visibility transition! Although opacity appears to do the right thing, fully transparent elements (with opacity:0) still receive mouse events. So e.g. links on an element that was faded out with an opacity transition alone, still respond to clicks (although not visible) and links behind the faded element do not work (although being visible through the faded element). See http://taccgl.org/blog/css-transition-opacity-for-fade-effects.html.

This strange behavior can be avoided by just using both transitions, the transition on visibility and the transition on opacity. Thereby the visibility property is used to disable mouse events for the element while opacity is used for the visual effect. However care must be taken not to hide the element while the visual effect is playing, which would otherwise not be visible. Here the special semantics of the visibility transition becomes handy. When hiding an element the element stays visible while playing the visual effect and is hidden afterwards. On the other hand when revealing an element, the visibility transition makes the element visible immediately, i.e. before playing the visual effect.

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

This worked for me in Luna elementary OS

sudo apt-get install libxtst6:i386

Scala Doubles, and Precision

For those how are interested, here are some times for the suggested solutions...

Rounding
Java Formatter: Elapsed Time: 105
Scala Formatter: Elapsed Time: 167
BigDecimal Formatter: Elapsed Time: 27

Truncation
Scala custom Formatter: Elapsed Time: 3 

Truncation is the fastest, followed by BigDecimal. Keep in mind these test were done running norma scala execution, not using any benchmarking tools.

object TestFormatters {

  val r = scala.util.Random

  def textFormatter(x: Double) = new java.text.DecimalFormat("0.##").format(x)

  def scalaFormatter(x: Double) = "$pi%1.2f".format(x)

  def bigDecimalFormatter(x: Double) = BigDecimal(x).setScale(2, BigDecimal.RoundingMode.HALF_UP).toDouble

  def scalaCustom(x: Double) = {
    val roundBy = 2
    val w = math.pow(10, roundBy)
    (x * w).toLong.toDouble / w
  }

  def timed(f: => Unit) = {
    val start = System.currentTimeMillis()
    f
    val end = System.currentTimeMillis()
    println("Elapsed Time: " + (end - start))
  }

  def main(args: Array[String]): Unit = {

    print("Java Formatter: ")
    val iters = 10000
    timed {
      (0 until iters) foreach { _ =>
        textFormatter(r.nextDouble())
      }
    }

    print("Scala Formatter: ")
    timed {
      (0 until iters) foreach { _ =>
        scalaFormatter(r.nextDouble())
      }
    }

    print("BigDecimal Formatter: ")
    timed {
      (0 until iters) foreach { _ =>
        bigDecimalFormatter(r.nextDouble())
      }
    }

    print("Scala custom Formatter (truncation): ")
    timed {
      (0 until iters) foreach { _ =>
        scalaCustom(r.nextDouble())
      }
    }
  }

}

How to read from standard input in the console?

Can also be done like this:-

package main
import "fmt"     

func main(){
    var myname string
fmt.Scanf("%s", &myname)           
fmt.Println("Hello", myname)       
}

How to detect the device orientation using CSS media queries?

@media all and (orientation:portrait) {
/* Style adjustments for portrait mode goes here */
}

@media all and (orientation:landscape) {
  /* Style adjustments for landscape mode goes here */
}

but it still looks like you have to experiment

Unable to open debugger port in IntelliJ IDEA

In my case I had another project open in IntelliJ, and had Tomcat running in debug mode in that project. Stopping that instance of Tomcat resolved the issue.

Sort a single String in Java

No there is no built-in String method. You can convert it to a char array, sort it using Arrays.sort and convert that back into a String.

String test= "edcba";
char[] ar = test.toCharArray();
Arrays.sort(ar);
String sorted = String.valueOf(ar);

Or, when you want to deal correctly with locale-specific stuff like uppercase and accented characters:

import java.text.Collator;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Locale;

public class Test
{
  public static void main(String[] args)
  {
    Collator collator = Collator.getInstance(new Locale("fr", "FR"));
    String original = "éDedCBcbAàa";
    String[] split = original.split("");
    Arrays.sort(split, collator);
    String sorted = "";
    for (int i = 0; i < split.length; i++)
    {
      sorted += split[i];
    }
    System.out.println(sorted); // "aAàbBcCdDeé"
  }
}

How to make a submit out of a <a href...>...</a> link?

<input type="image" name="your_image_name" src="your_image_url.png" />

This will send the your_image_name.x and your_image_name.y values as it submits the form, which are the x and y coordinates of the position the user clicked the image.

How to find the cumulative sum of numbers in a list?

Assignment expressions from PEP 572 (new in Python 3.8) offer yet another way to solve this:

time_interval = [4, 6, 12]

total_time = 0
cum_time = [total_time := total_time + t for t in time_interval]

Cordova : Requirements check failed for JDK 1.8 or greater

It seems the Android SDK don't support Java 9. Downgrade to 8 if you dont want to go all the way back to JDK 1.8 which to me is ridiculous. JDK 8 work for me but be sure to set the JAVA_HOME environment variable to the location of your JDK installation correctly.

Do I need to pass the full path of a file in another directory to open()?

You have to specify the path that you are working on:

source = '/home/test/py_test/'
for root, dirs, filenames in os.walk(source):
    for f in filenames:
        print f
        fullpath = os.path.join(source, f)
        log = open(fullpath, 'r')

Why does JPA have a @Transient annotation?

Purpose is different:

The transient keyword and @Transient annotation have two different purposes: one deals with serialization and one deals with persistence. As programmers, we often marry these two concepts into one, but this is not accurate in general. Persistence refers to the characteristic of state that outlives the process that created it. Serialization in Java refers to the process of encoding/decoding an object's state as a byte stream.

The transient keyword is a stronger condition than @Transient:

If a field uses the transient keyword, that field will not be serialized when the object is converted to a byte stream. Furthermore, since JPA treats fields marked with the transient keyword as having the @Transient annotation, the field will not be persisted by JPA either.

On the other hand, fields annotated @Transient alone will be converted to a byte stream when the object is serialized, but it will not be persisted by JPA. Therefore, the transient keyword is a stronger condition than the @Transient annotation.

Example

This begs the question: Why would anyone want to serialize a field that is not persisted to the application's database? The reality is that serialization is used for more than just persistence. In an Enterprise Java application there needs to be a mechanism to exchange objects between distributed components; serialization provides a common communication protocol to handle this. Thus, a field may hold critical information for the purpose of inter-component communication; but that same field may have no value from a persistence perspective.

For example, suppose an optimization algorithm is run on a server, and suppose this algorithm takes several hours to complete. To a client, having the most up-to-date set of solutions is important. So, a client can subscribe to the server and receive periodic updates during the algorithm's execution phase. These updates are provided using the ProgressReport object:

@Entity
public class ProgressReport implements Serializable{

    private static final long serialVersionUID = 1L;

    @Transient
    long estimatedMinutesRemaining;
    String statusMessage;
    Solution currentBestSolution;

}

The Solution class might look like this:

@Entity
public class Solution implements Serializable{

    private static final long serialVersionUID = 1L;

    double[][] dataArray;
    Properties properties;
}

The server persists each ProgressReport to its database. The server does not care to persist estimatedMinutesRemaining, but the client certainly cares about this information. Therefore, the estimatedMinutesRemaining is annotated using @Transient. When the final Solution is located by the algorithm, it is persisted by JPA directly without using a ProgressReport.

How to measure the a time-span in seconds using System.currentTimeMillis()?

For conversion of milliseconds to seconds, since 1 second = 10³ milliseconds:

//here m will be in seconds
long m = System.currentTimeMillis()/1000;

//here m will be in minutes
long m = System.currentTimeMillis()/1000/60; //this will give in mins

PowerShell try/catch/finally

That is very odd.

I went through ItemNotFoundException's base classes and tested the following multiple catches to see what would catch it:

try {
  remove-item C:\nonexistent\file.txt -erroraction stop
}
catch [System.Management.Automation.ItemNotFoundException] {
  write-host 'ItemNotFound'
}
catch [System.Management.Automation.SessionStateException] {
  write-host 'SessionState'
}
catch [System.Management.Automation.RuntimeException] {
  write-host 'RuntimeException'
}
catch [System.SystemException] {
  write-host 'SystemException'
}
catch [System.Exception] {
  write-host 'Exception'
}
catch {
  write-host 'well, darn'
}

As it turns out, the output was 'RuntimeException'. I also tried it with a different exception CommandNotFoundException:

try {
  do-nonexistent-command
}
catch [System.Management.Automation.CommandNotFoundException] {
  write-host 'CommandNotFoundException'
}
catch {
  write-host 'well, darn'
}

That output 'CommandNotFoundException' correctly.

I vaguely remember reading elsewhere (though I couldn't find it again) of problems with this. In such cases where exception filtering didn't work correctly, they would catch the closest Type they could and then use a switch. The following just catches Exception instead of RuntimeException, but is the switch equivalent of my first example that checks all base types of ItemNotFoundException:

try {
  Remove-Item C:\nonexistent\file.txt -ErrorAction Stop
}
catch [System.Exception] {
  switch($_.Exception.GetType().FullName) {
    'System.Management.Automation.ItemNotFoundException' {
      write-host 'ItemNotFound'
    }
    'System.Management.Automation.SessionStateException' {
      write-host 'SessionState'
    }
    'System.Management.Automation.RuntimeException' {
      write-host 'RuntimeException'
    }
    'System.SystemException' {
      write-host 'SystemException'
    }
    'System.Exception' {
      write-host 'Exception'
    }
    default {'well, darn'}
  }
}

This writes 'ItemNotFound', as it should.

Can I force pip to reinstall the current version?

If you want to reinstall packages specified in a requirements.txt file, without upgrading, so just reinstall the specific versions specified in the requirements.txt file:

pip install -r requirements.txt --ignore-installed

How can I get a favicon to show up in my django app?

Now(in 2020), You could add a base tag in html file.

<head>
<base href="https://www.example.com/static/"> 
</head>

Get path to execution directory of Windows Forms application

Both of the examples are in VB.NET.

Debug path:

TextBox1.Text = My.Application.Info.DirectoryPath

EXE path:

TextBox2.Text = IO.Path.GetFullPath(Application.ExecutablePath)

Prevent cell numbers from incrementing in a formula in Excel

TL:DR
row lock = A$5
column lock = $A5
Both = $A$5

Below are examples of how to use the Excel lock reference $ when creating your formulas

To prevent increments when moving from one row to another put the $ after the column letter and before the row number. e.g. A$5

To prevent increments when moving from one column to another put the $ before the row number. e.g. $A5

To prevent increments when moving from one column to another or from one row to another put the $ before the row number and before the column letter. e.g. $A$5

Using the lock reference will also prevent increments when dragging cells over to duplicate calculations.

Clear back stack using fragments

Just use this method and pass Context & Fragment tag upto which we need to remove the backstake fragments.

Usage

clearFragmentByTag(context, FragmentName.class.getName());



public static void clearFragmentByTag(Context context, String tag) {
    try {
        FragmentManager fm = ((AppCompatActivity) context).getSupportFragmentManager();

        for (int i = fm.getBackStackEntryCount() - 1; i >= 0; i--) {
            String backEntry = fm.getBackStackEntryAt(i).getName();
            if (backEntry.equals(tag)) {
                break;
            } else {
                 fm.popBackStack();
            }
        }
    } catch (Exception e) {
        System.out.print("!====Popbackstack error : " + e);
        e.printStackTrace();
    }
}

Undefined reference to pow( ) in C, despite including math.h

You need to link with the math library:

gcc -o sphere sphere.c -lm

The error you are seeing: error: ld returned 1 exit status is from the linker ld (part of gcc that combines the object files) because it is unable to find where the function pow is defined.

Including math.h brings in the declaration of the various functions and not their definition. The def is present in the math library libm.a. You need to link your program with this library so that the calls to functions like pow() are resolved.

get list of packages installed in Anaconda

For script creation at Windows cmd or powershell prompt:

C:\ProgramData\Anaconda3\Scripts\activate.bat C:\ProgramData\Anaconda3
conda list
pip list

Validate decimal numbers in JavaScript - IsNumeric()

An integer value can be verified by:

function isNumeric(value) {
    var bool = isNaN(+value));
    bool = bool || (value.indexOf('.') != -1);
    bool = bool || (value.indexOf(",") != -1);
    return !bool;
};

This way is easier and faster! All tests are checked!

How to use the divide function in the query?

Try something like this

select Cast((SPGI09_EARLY_OVER_T – (SPGI09_OVER_WK_EARLY_ADJUST_T) / (SPGI09_EARLY_OVER_T + SPGR99_LATE_CM_T  + SPGR99_ON_TIME_Q)) as varchar(20) + '%' as percentageAmount
from CSPGI09_OVERSHIPMENT

I presume the value is a representation in percentage - if not convert it to a valid percentage total, then add the % sign and convert the column to varchar.

How to encrypt/decrypt data in php?

Here is an example using openssl_encrypt

//Encryption:
$textToEncrypt = "My Text to Encrypt";
$encryptionMethod = "AES-256-CBC";
$secretHash = "encryptionhash";
$iv = mcrypt_create_iv(16, MCRYPT_RAND);
$encryptedText = openssl_encrypt($textToEncrypt,$encryptionMethod,$secretHash, 0, $iv);

//Decryption:
$decryptedText = openssl_decrypt($encryptedText, $encryptionMethod, $secretHash, 0, $iv);
print "My Decrypted Text: ". $decryptedText;

Explanation of "ClassCastException" in Java

Exception is not a subclass of RuntimeException -> ClassCastException

    final Object  exception = new Exception();
    final Exception data = (RuntimeException)exception ;
    System.out.println(data);

Content is not allowed in Prolog SAXParserException

to simply remove it, paste your xml file into notepad, you'll see the extra character before the first tag. Remove it & paste back into your file - bof

Android: View.setID(int id) programmatically - how to avoid ID conflicts?

Since API 17, the View class has a static method generateViewId() that will

generate a value suitable for use in setId(int)

How to remove MySQL completely with config and library files?

With the command:

sudo apt-get remove --purge mysql\*

you can delete anything related to packages named mysql. Those commands are only valid on debian / debian-based linux distributions (Ubuntu for example).

You can list all installed mysql packages with the command:

sudo dpkg -l | grep -i mysql

For more cleanup of the package cache, you can use the command:

sudo apt-get clean

Also, remember to use the command:

sudo updatedb

Otherwise the "locate" command will display old data.

To install mysql again, use the following command:

sudo apt-get install libmysqlclient-dev mysql-client

This will install the mysql client, libmysql and its headers files.

To install the mysql server, use the command:

sudo apt-get install mysql-server

Printing to the console in Google Apps Script?

Just to build on vinnief's hacky solution above, I use MsgBox like this:

Browser.msgBox('BorderoToMatriz', Browser.Buttons.OK_CANCEL);

and it acts kinda like a break point, stops the script and outputs whatever string you need to a pop-up box. I find especially in Sheets, where I have trouble with Logger.log, this provides an adequate workaround most times.

How to handle checkboxes in ASP.NET MVC forms?

Here's what I've been doing.

View:


<input type="checkbox" name="applyChanges" />

Controller:


var checkBox = Request.Form["applyChanges"];

if (checkBox == "on")
{
...
}

I found the Html.* helper methods not so useful in some cases, and that I was better off doing it in plain old HTML. This being one of them, the other one that comes to mind is radio buttons.

Edit: this is on Preview 5, obviously YMMV between versions.

How do I test if a variable is a number in Bash?

test -z "${i//[0-9]}" && echo digits || echo no no no

${i//[0-9]} replaces any digit in the value of $i with an empty string, see man -P 'less +/parameter\/' bash. -z checks if resulting string has zero length.

if you also want to exclude the case when $i is empty, you could use one of these constructions:

test -n "$i" && test -z "${i//[0-9]}" && echo digits || echo not a number
[[ -n "$i" && -z "${i//[0-9]}" ]] && echo digits || echo not a number

Xcode 6 Storyboard the wrong size?

Go to Attributes Inspector(right top corner) In the Simulated Metrics, which has Size, Orientation, Status Bar, Top Bar, Bottom Bar properties. For SIZE, change Inferred --> Freeform.

Creating runnable JAR with Gradle

You can define a jar artifact in the module settings (or project structure).

  • Right click the module > Open module settings > Artifacts > + > JAR > from modules with dependencies.
  • Set the main class.

Making a jar is then as easy as clicking "Build artifact..." from the Build menu. As a bonus, you can package all the dependencies into a single jar.

Tested on IntelliJ IDEA 14 Ultimate.

Playing .mp3 and .wav in Java?

Java FX has Media and MediaPlayer classes which will play mp3 files.

Example code:

String bip = "bip.mp3";
Media hit = new Media(new File(bip).toURI().toString());
MediaPlayer mediaPlayer = new MediaPlayer(hit);
mediaPlayer.play();

You will need the following import statements:

import java.io.File;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;

Eclipse - Failed to create the java virtual machine

I had also entered the path of MinGW complier for C++. After removing it, the error disappeared.

jquery dialog save cancel button styling

As of jquery ui version 1.8.16 below is how I got it working.

$('#element').dialog({
  buttons: { 
      "Save": {  
          text: 'Save', 
          class: 'btn primary', 
          click: function () {
              // do stuff
          }
      }
});

How can I find my php.ini on wordpress?

Open .htaccess file in a code editor like sublime text and then add..

php_value upload_max_filesize 1000M
php_value post_max_size 2000M
php_value memory_limit 3000M
php_value max_execution_time 1800
php_value max_input_time 180

hope it helps..............it did for me.

Create a sample login page using servlet and JSP?

You're comparing the message with the empty string using ==.

First, your comparison is wrong because the message will be null (and not the empty string).

Second, it's wrong because Objects must be compared with equals() and not with ==.

Third, it's wrong because you should avoid scriptlets in JSP, and use the JSP EL, the JSTL, and other custom tags instead:

<c:id test="${!empty message}">
    <c:out value="${message}"/>
</c:if>

Why use the INCLUDE clause when creating an index?

The reasons why (including the data in the leaf level of the index) have been nicely explained. The reason that you give two shakes about this, is that when you run your query, if you don't have the additional columns included (new feature in SQL 2005) the SQL Server has to go to the clustered index to get the additional columns which takes more time, and adds more load to the SQL Server service, the disks, and the memory (buffer cache to be specific) as new data pages are loaded into memory, potentially pushing other more often needed data out of the buffer cache.

Go to "next" iteration in JavaScript forEach loop

JavaScript's forEach works a bit different from how one might be used to from other languages for each loops. If reading on the MDN, it says that a function is executed for each of the elements in the array, in ascending order. To continue to the next element, that is, run the next function, you can simply return the current function without having it do any computation.

Adding a return and it will go to the next run of the loop:

_x000D_
_x000D_
var myArr = [1,2,3,4];_x000D_
_x000D_
myArr.forEach(function(elem){_x000D_
  if (elem === 3) {_x000D_
    return;_x000D_
  }_x000D_
_x000D_
  console.log(elem);_x000D_
});
_x000D_
_x000D_
_x000D_

Output: 1, 2, 4

How do I put hint in a asp:textbox

 <asp:TextBox runat="server" ID="txtPassword" placeholder="Password">

This will work you might some time feel that it is not working due to Intellisence not showing placeholder

Java generics - ArrayList initialization

Think of the ? as to mean "unknown". Thus, "ArrayList<? extends Object>" is to say "an unknown type that (or as long as it)extends Object". Therefore, needful to say, arrayList.add(3) would be putting something you know, into an unknown. I.e 'Forgetting'.

awk - concatenate two string variable and assign to a third

Just use var = var1 var2 and it will automatically concatenate the vars var1 and var2:

awk '{new_var=$1$2; print new_var}' file

You can put an space in between with:

awk '{new_var=$1" "$2; print new_var}' file

Which in fact is the same as using FS, because it defaults to the space:

awk '{new_var=$1 FS $2; print new_var}' file

Test

$ cat file
hello how are you
i am fine
$ awk '{new_var=$1$2; print new_var}' file
hellohow
iam
$ awk '{new_var=$1 FS $2; print new_var}' file
hello how
i am

You can play around with it in ideone: http://ideone.com/4u2Aip

How do I find and replace all occurrences (in all files) in Visual Studio Code?

Visual Studio Code: Version: 1.53.2


If you are looking for the answer in 2021 (like I was), the answer is here on the Microsoft website but honestly hard to follow.

Go to Edit > Replace in Files

enter image description here

From there it is similar to the search funtionality for a single file.

I changed the name of a class I was using across files and this worked perfectly.

Note: If you cannot find the Replace in Files option, first click on the Search icon (magnifying glass) and then it will appear.

How is Perl's @INC constructed? (aka What are all the ways of affecting where Perl modules are searched for?)

We will look at how the contents of this array are constructed and can be manipulated to affect where the Perl interpreter will find the module files.

  1. Default @INC

    Perl interpreter is compiled with a specific @INC default value. To find out this value, run env -i perl -V command (env -i ignores the PERL5LIB environmental variable - see #2) and in the output you will see something like this:

    $ env -i perl -V
    ...
    @INC:
     /usr/lib/perl5/site_perl/5.18.0/x86_64-linux-thread-multi-ld
     /usr/lib/perl5/site_perl/5.18.0
     /usr/lib/perl5/5.18.0/x86_64-linux-thread-multi-ld
     /usr/lib/perl5/5.18.0
     .
    

Note . at the end; this is the current directory (which is not necessarily the same as the script's directory). It is missing in Perl 5.26+, and when Perl runs with -T (taint checks enabled).

To change the default path when configuring Perl binary compilation, set the configuration option otherlibdirs:

Configure -Dotherlibdirs=/usr/lib/perl5/site_perl/5.16.3

  1. Environmental variable PERL5LIB (or PERLLIB)

    Perl pre-pends @INC with a list of directories (colon-separated) contained in PERL5LIB (if it is not defined, PERLLIB is used) environment variable of your shell. To see the contents of @INC after PERL5LIB and PERLLIB environment variables have taken effect, run perl -V.

    $ perl -V
    ...
    %ENV:
      PERL5LIB="/home/myuser/test"
    @INC:
     /home/myuser/test
     /usr/lib/perl5/site_perl/5.18.0/x86_64-linux-thread-multi-ld
     /usr/lib/perl5/site_perl/5.18.0
     /usr/lib/perl5/5.18.0/x86_64-linux-thread-multi-ld
     /usr/lib/perl5/5.18.0
     .
    
  2. -I command-line option

    Perl pre-pends @INC with a list of directories (colon-separated) passed as value of the -I command-line option. This can be done in three ways, as usual with Perl options:

    • Pass it on command line:

      perl -I /my/moduledir your_script.pl
      
    • Pass it via the first line (shebang) of your Perl script:

      #!/usr/local/bin/perl -w -I /my/moduledir
      
    • Pass it as part of PERL5OPT (or PERLOPT) environment variable (see chapter 19.02 in Programming Perl)

  3. Pass it via the lib pragma

    Perl pre-pends @INC with a list of directories passed in to it via use lib.

    In a program:

    use lib ("/dir1", "/dir2");
    

    On the command line:

    perl -Mlib=/dir1,/dir2
    

    You can also remove the directories from @INC via no lib.

  4. You can directly manipulate @INC as a regular Perl array.

    Note: Since @INC is used during the compilation phase, this must be done inside of a BEGIN {} block, which precedes the use MyModule statement.

    • Add directories to the beginning via unshift @INC, $dir.

    • Add directories to the end via push @INC, $dir.

    • Do anything else you can do with a Perl array.

Note: The directories are unshifted onto @INC in the order listed in this answer, e.g. default @INC is last in the list, preceded by PERL5LIB, preceded by -I, preceded by use lib and direct @INC manipulation, the latter two mixed in whichever order they are in Perl code.

References:

There does not seem to be a comprehensive @INC FAQ-type post on Stack Overflow, so this question is intended as one.

When to use each approach?

  • If the modules in a directory need to be used by many/all scripts on your site, especially run by multiple users, that directory should be included in the default @INC compiled into the Perl binary.

  • If the modules in the directory will be used exclusively by a specific user for all the scripts that user runs (or if recompiling Perl is not an option to change default @INC in previous use case), set the users' PERL5LIB, usually during user login.

    Note: Please be aware of the usual Unix environment variable pitfalls - e.g. in certain cases running the scripts as a particular user does not guarantee running them with that user's environment set up, e.g. via su.

  • If the modules in the directory need to be used only in specific circumstances (e.g. when the script(s) is executed in development/debug mode, you can either set PERL5LIB manually, or pass the -I option to perl.

  • If the modules need to be used only for specific scripts, by all users using them, use use lib/no lib pragmas in the program itself. It also should be used when the directory to be searched needs to be dynamically determined during runtime - e.g. from the script's command line parameters or script's path (see the FindBin module for very nice use case).

  • If the directories in @INC need to be manipulated according to some complicated logic, either impossible to too unwieldy to implement by combination of use lib/no lib pragmas, then use direct @INC manipulation inside BEGIN {} block or inside a special purpose library designated for @INC manipulation, which must be used by your script(s) before any other modules are used.

    An example of this is automatically switching between libraries in prod/uat/dev directories, with waterfall library pickup in prod if it's missing from dev and/or UAT (the last condition makes the standard "use lib + FindBin" solution fairly complicated. A detailed illustration of this scenario is in How do I use beta Perl modules from beta Perl scripts?.

  • An additional use case for directly manipulating @INC is to be able to add subroutine references or object references (yes, Virginia, @INC can contain custom Perl code and not just directory names, as explained in When is a subroutine reference in @INC called?).

Catch error if iframe src fails to load . Error :-"Refused to display 'http://www.google.co.in/' in a frame.."

I have the same problem, chrome can't fire onerror when iframe src load error.

but in my case, I just need make a cross domain http request, so I use script src/onload/onerror instead of iframe. it's working well.

How to get my project path?

This gives you the root folder:

System.AppDomain.CurrentDomain.BaseDirectory

You can navigate from here using .. or ./ etc.. , Appending .. takes you to folder where .sln file can be found

For .NET framework (thanks to Adiono comment)

Path.GetFullPath(Path.Combine(AppDomain.CurrentDomain.BaseDirectory,"..\\..\\"))

For .NET core here is a way to do it (thanks to nopara73 comment)

Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..\\..\\..\\")) ;

CORS header 'Access-Control-Allow-Origin' missing

in your ajax request, adding:

dataType: "jsonp",

after line :

type: 'GET',

should solve this problem ..

hope this help you

How to compare only date components from DateTime in EF?

Use the class EntityFunctions for trimming the time portion.

using System.Data.Objects;    

var bla = (from log in context.Contacts
           where EntityFunctions.TruncateTime(log.ModifiedDate) ==  EntityFunctions.TruncateTime(today.Date)
           select log).FirstOrDefault();

Source: http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/84d4e18b-7545-419b-9826-53ff1a0e2a62/

UPDATE

As of EF 6.0 and later EntityFunctions is replaced by DbFunctions.

Is <div style="width: ;height: ;background: "> CSS?

1)Yes it is, when there is style then it is styling your code(css).2) is belong to html it is like a container that keep your css.

Moment JS start and end of given month

you can use this directly for the end or start date of the month

new moment().startOf('month').format("YYYY-DD-MM");
new moment().endOf("month").format("YYYY-DD-MM");

you can change the format by defining a new format

Is it possible to have a default parameter for a mysql stored procedure?

No, this is not supported in MySQL stored routine syntax.

Feel free to submit a feature request at bugs.mysql.com.

must appear in the GROUP BY clause or be used in an aggregate function

In Postgres, you can also use the special DISTINCT ON (expression) syntax:

SELECT DISTINCT ON (cname) 
    cname, wmname, avg
FROM 
    makerar 
ORDER BY 
    cname, avg DESC ;

Setting up and using Meld as your git difftool and mergetool

This is an answer targeting primarily developers using Windows, as the path syntax of the diff tool differs from other platforms.

I use Kdiff3 as the git mergetool, but to set up the git difftool as Meld, I first installed the latest version of Meld from Meldmerge.org then added the following to my global .gitconfig using:

git config --global -e

Note, if you rather want Sublime Text 3 instead of the default Vim as core ditor, you can add this to the .gitconfig file:

[core]
editor = 'c:/Program Files/Sublime Text 3/sublime_text.exe'

Then you add inn Meld as the difftool

[diff]
tool = meld
guitool = meld 

[difftool "meld"]
cmd = \"C:/Program Files (x86)/Meld/Meld.exe\" \"$LOCAL\" \"$REMOTE\" --label \"DIFF 
(ORIGINAL MY)\"
prompt = false
path = C:\\Program Files (x86)\\Meld\\Meld.exe

Note the leading slash in the cmd above, on Windows it is necessary.

It is also possible to set up an alias to show the current git diff with a --dir-diff option. This will list the changed files inside Meld, which is handy when you have altered multiple files (a very common scenario indeed).

The alias looks like this inside the .gitconfig file, beneath [alias] section:

showchanges = difftool --dir-diff

To show the changes I have made to the code I then just enter the following command:

git showchanges

The following image shows how this --dir-diff option can show a listing of changed files (example): Meld showing list of files with changes between the $LOCAL and $REMOTE

Then it is possible to click on each file and show the changes inside Meld.