Programs & Examples On #Cactus

Jakarta Cactus is a framework for unit testing server-side java code. Apache retired Jakarta Cactus on 2011/08/05.

How to set image for bar button with swift?

Your problem is because of the way the icon has been made - it doesn't conform to Apple's custom tab bar icon specs:

To design a custom bar icon, follow these guidelines:

  • Use pure white with appropriate alpha transparency.
  • Don’t include a drop shadow.
  • Use antialiasing.

(From the guidelines.)

Something that would be possible looks like this. You can find such icons on most free tab bar icon sites.

Button example

How to get memory usage at runtime using C++?

On Linux, I've never found an ioctl() solution. For our applications, we coded a general utility routine based on reading files in /proc/pid. There are a number of these files which give differing results. Here's the one we settled on (the question was tagged C++, and we handled I/O using C++ constructs, but it should be easily adaptable to C i/o routines if you need to):

#include <unistd.h>
#include <ios>
#include <iostream>
#include <fstream>
#include <string>

//////////////////////////////////////////////////////////////////////////////
//
// process_mem_usage(double &, double &) - takes two doubles by reference,
// attempts to read the system-dependent data for a process' virtual memory
// size and resident set size, and return the results in KB.
//
// On failure, returns 0.0, 0.0

void process_mem_usage(double& vm_usage, double& resident_set)
{
   using std::ios_base;
   using std::ifstream;
   using std::string;

   vm_usage     = 0.0;
   resident_set = 0.0;

   // 'file' stat seems to give the most reliable results
   //
   ifstream stat_stream("/proc/self/stat",ios_base::in);

   // dummy vars for leading entries in stat that we don't care about
   //
   string pid, comm, state, ppid, pgrp, session, tty_nr;
   string tpgid, flags, minflt, cminflt, majflt, cmajflt;
   string utime, stime, cutime, cstime, priority, nice;
   string O, itrealvalue, starttime;

   // the two fields we want
   //
   unsigned long vsize;
   long rss;

   stat_stream >> pid >> comm >> state >> ppid >> pgrp >> session >> tty_nr
               >> tpgid >> flags >> minflt >> cminflt >> majflt >> cmajflt
               >> utime >> stime >> cutime >> cstime >> priority >> nice
               >> O >> itrealvalue >> starttime >> vsize >> rss; // don't care about the rest

   stat_stream.close();

   long page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024; // in case x86-64 is configured to use 2MB pages
   vm_usage     = vsize / 1024.0;
   resident_set = rss * page_size_kb;
}

int main()
{
   using std::cout;
   using std::endl;

   double vm, rss;
   process_mem_usage(vm, rss);
   cout << "VM: " << vm << "; RSS: " << rss << endl;
}

HttpGet with HTTPS : SSLPeerUnverifiedException

Your local JVM or remote server may not have the required ciphers. go here

https://www.oracle.com/java/technologies/javase-jce8-downloads.html

and download the zip file that contains: US_export_policy.jar and local_policy.jar

replace the existing files (you need to find the existing path in your JVM).

on a Mac, my path was here. /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/jre/lib/security

this worked for me.

Leverage browser caching, how on apache or .htaccess?

I took my chance to provide full .htaccess code to pass on Google PageSpeed Insight:

  1. Enable compression
  2. Leverage browser caching
# Enable Compression
<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
  AddOutputFilterByType DEFLATE application/x-font
  AddOutputFilterByType DEFLATE application/x-font-opentype
  AddOutputFilterByType DEFLATE application/x-font-otf
  AddOutputFilterByType DEFLATE application/x-font-truetype
  AddOutputFilterByType DEFLATE application/x-font-ttf
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE font/opentype
  AddOutputFilterByType DEFLATE font/otf
  AddOutputFilterByType DEFLATE font/ttf
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE image/x-icon
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/javascript
  AddOutputFilterByType DEFLATE text/plain
</IfModule>
<IfModule mod_gzip.c>
  mod_gzip_on Yes
  mod_gzip_dechunk Yes
  mod_gzip_item_include file .(html?|txt|css|js|php|pl)$
  mod_gzip_item_include handler ^cgi-script$
  mod_gzip_item_include mime ^text/.*
  mod_gzip_item_include mime ^application/x-javascript.*
  mod_gzip_item_exclude mime ^image/.*
  mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</IfModule>

# Leverage Browser Caching
<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType image/jpg "access 1 year"
  ExpiresByType image/jpeg "access 1 year"
  ExpiresByType image/gif "access 1 year"
  ExpiresByType image/png "access 1 year"
  ExpiresByType text/css "access 1 month"
  ExpiresByType text/html "access 1 month"
  ExpiresByType application/pdf "access 1 month"
  ExpiresByType text/x-javascript "access 1 month"
  ExpiresByType application/x-shockwave-flash "access 1 month"
  ExpiresByType image/x-icon "access 1 year"
  ExpiresDefault "access 1 month"
</IfModule>
<IfModule mod_headers.c>
  <filesmatch "\.(ico|flv|jpg|jpeg|png|gif|css|swf)$">
  Header set Cache-Control "max-age=2678400, public"
  </filesmatch>
  <filesmatch "\.(html|htm)$">
  Header set Cache-Control "max-age=7200, private, must-revalidate"
  </filesmatch>
  <filesmatch "\.(pdf)$">
  Header set Cache-Control "max-age=86400, public"
  </filesmatch>
  <filesmatch "\.(js)$">
  Header set Cache-Control "max-age=2678400, private"
  </filesmatch>
</IfModule>

There is also some configurations for various web servers see here.
Hope this would help to get the 100/100 score.

optimized page score

Where can I find the Java SDK in Linux after installing it?

This is the best way which worked for me Execute this Command:-

$(dirname $(readlink $(which javac)))/java_home

android - setting LayoutParams programmatically

Just replace from bottom and add this

tv.setLayoutParams(new ViewGroup.LayoutParams(
    ViewGroup.LayoutParams.WRAP_CONTENT,
    ViewGroup.LayoutParams.WRAP_CONTENT));

before

llview.addView(tv);

C# Inserting Data from a form into an access Database

and doesnt give any clues

Yes it does, unfortunately your code is ignoring all of those clues. Take a look at your exception handler:

catch (OleDbException  ex)
{
    MessageBox.Show(ex.Source);
    conn.Close();
}

All you're examining is the source of the exception. Which, in this case, is "Microsoft Access Database Engine". You're not examining the error message itself, or the stack trace, or any inner exception, or anything useful about the exception.

Don't ignore the exception, it contains information about what went wrong and why.

There are various logging tools out there (NLog, log4net, etc.) which can help you log useful information about an exception. Failing that, you should at least capture the exception message, stack trace, and any inner exception(s). Currently you're ignoring the error, which is why you're not able to solve the error.

In your debugger, place a breakpoint inside the catch block and examine the details of the exception. You'll find it contains a lot of information.

How to remove/delete a large file from commit history in Git repository?

This will remove it from your history

git filter-branch --force --index-filter 'git rm -r --cached --ignore-unmatch bigfile.txt' --prune-empty --tag-name-filter cat -- --all

Check if a variable is a string in JavaScript

The following method will check if any variable is a string (including variables that do not exist).

const is_string = value => {
  try {
    return typeof value() === 'string';
  } catch (error) {
    return false;
  }
};

let example = 'Hello, world!';

console.log(is_string(() => example)); // true
console.log(is_string(() => variable_doesnt_exist)); // false

Deserializing JSON data to C# using JSON.NET

You can use:

JsonConvert.PopulateObject(json, obj);

here: json is the json string,obj is the target object. See: example

Note: PopulateObject() will not erase obj's list data, after Populate(), obj's list member will contains its original data and data from json string

Automatic prune with Git fetch or pull

If you want to always prune when you fetch, I can suggest to use Aliases.

Just type git config -e to open your editor and change the configuration for a specific project and add a section like

[alias]
pfetch = fetch --prune   

the when you fetch with git pfetch the prune will be done automatically.

Build a simple HTTP server in C

http://www.manning.com/hethmon/ -- "Illustrated Guide to HTTP by Paul S. Hethmon" from Manning is a very good book to learn HTTP protocol and will be very useful to someone implementing it /extending it.

MySQL Error 1153 - Got a packet bigger than 'max_allowed_packet' bytes

Error:

ERROR 1153 (08S01) at line 6772: Got a packet bigger than 'max_allowed_packet' bytes Operation failed with exitcode 1

QUERY:

SET GLOBAL max_allowed_packet=1073741824;
SHOW VARIABLES LIKE 'max_allowed_packet'; 

Max value:

Default Value (MySQL >= 8.0.3)  67108864
Default Value (MySQL <= 8.0.2)  4194304
Minimum Value   1024
Maximum Value   1073741824

Forbidden You don't have permission to access /wp-login.php on this server

The solution is to add this to the beginning of your .htaccess

<Files wp-login.php>
Order Deny,Allow
Deny from all
Allow from all
</Files>

It's because many hosts were under attack, using the wordpress from their clients.

How do you normalize a file path in Bash?

My recent solution was:

pushd foo/bar/..
dir=`pwd`
popd

Based on the answer of Tim Whitcomb.

Array of arrays (Python/NumPy)

It seems strange that you would write arrays without commas (is that a MATLAB syntax?)

Have you tried going through NumPy's documentation on multi-dimensional arrays?

It seems NumPy has a "Python-like" append method to add items to a NumPy n-dimensional array:

>>> p = np.array([[1,2],[3,4]])

>>> p = np.append(p, [[5,6]], 0)

>>> p = np.append(p, [[7],[8],[9]],1)

>>> p
array([[1, 2, 7], [3, 4, 8], [5, 6, 9]])

It has also been answered already...

From the documentation for MATLAB users:

You could use a matrix constructor which takes a string in the form of a matrix MATLAB literal:

mat("1 2 3; 4 5 6")

or

matrix("[1 2 3; 4 5 6]")

Please give it a try and tell me how it goes.

Simulate limited bandwidth from within Chrome?

If you are running Linux, the following command is really useful for this:

trickle -s -d 50 -w 100 firefox

The -s tells the command to run standalone, the -d 50 tells it to limit bandwidth to 50 KB/s, the -w 100 set the peak detection window size to 100 KB. firefox tells the command to start firefox with all of this rate limiting applied to any sites it attempts to load.

Update

Chrome 38 is out now and includes throttling. To find it, bring up the Developer Tools: Ctrl+Shift+I does it on my machine, otherwise Menu->More Tools->Developer Tools will bring you there.

Then Toggle Device Mode by clicking the phone in the upper left of the Developer Tools Panel (see the tooltip below).

Toggle device mode

Then activate throttling like so.

Activate Chrome throttling

If you find this a bit clunky, my suggestion above works for both Chrome and Firefox.

How to show/hide an element on checkbox checked/unchecked states using jQuery?

Try this

$(".answer").hide();
$(".coupon_question").click(function() {
    if($(this).is(":checked")) {
        $(".answer").show(300);
    } else {
        $(".answer").hide(200);
    }
});

FIDDLE

Set a request header in JavaScript

For people looking this up now:

It seems that now setting the User-Agent header is allowed since Firefox 43. See https://developer.mozilla.org/en-US/docs/Glossary/Forbidden_header_name for the current list of forbidden headers.

How to hide the Google Invisible reCAPTCHA badge

I decided to hide the badge on all pages except my contact page (using Wordpress):

/* Hides the reCAPTCHA on every page */
.grecaptcha-badge {
    visibility: hidden !important;
}

/* Shows the reCAPTCHA on the Contact page */
/* Obviously change the page number to your own */
.page-id-17 .grecaptcha-badge {
    visibility: visible !important;
}

I'm not a web developer so please correct me if there's something wrong.

EDIT: Updated to use visibility instead of display.

PHP: Return all dates between two dates in an array

Note that the answer provided by ViNce does NOT include the end date for the period.

If you are using PHP 5.3+, your best bet is to use a function like this:

/**
 * Generate an array of string dates between 2 dates
 *
 * @param string $start Start date
 * @param string $end End date
 * @param string $format Output format (Default: Y-m-d)
 *
 * @return array
 */
function getDatesFromRange($start, $end, $format = 'Y-m-d') {
    $array = array();
    $interval = new DateInterval('P1D');

    $realEnd = new DateTime($end);
    $realEnd->add($interval);

    $period = new DatePeriod(new DateTime($start), $interval, $realEnd);

    foreach($period as $date) { 
        $array[] = $date->format($format); 
    }

    return $array;
}

Then, you would call the function as expected:

getDatesFromRange('2010-10-01', '2010-10-05');

Run demo

Note about DatePeriod class: You can use the 4th parameter of DatePeriod to exclude the start date (DatePeriod::EXCLUDE_START_DATE) but you cannot, at this time, include the end date.

How to get values from selected row in DataGrid for Windows Form Application?

Description

Assuming i understand your question.

You can get the selected row using the DataGridView.SelectedRows Collection. If your DataGridView allows only one selected, have a look at my sample.

DataGridView.SelectedRows Gets the collection of rows selected by the user.

Sample

if (dataGridView1.SelectedRows.Count != 0)
{
    DataGridViewRow row = this.dataGridView1.SelectedRows[0];
    row.Cells["ColumnName"].Value
}

More Information

how to convert `content://media/external/images/media/Y` to `file:///storage/sdcard0/Pictures/X.jpg` in android?

If you just want the bitmap, This too works

InputStream inputStream = mContext.getContentResolver().openInputStream(uri);
Bitmap bmp = BitmapFactory.decodeStream(inputStream);
if( inputStream != null ) inputStream.close();

sample uri : content://media/external/images/media/12345

How can I measure the similarity between two images?

You might look at the code for the open source tool findimagedupes, though it appears to have been written in perl, so I can't say how easy it will be to parse...

Reading the findimagedupes page that I liked, I see that there is a C++ implementation of the same algorithm. Presumably this will be easier to understand.

And it appears you can also use gqview.

How do I get a div to float to the bottom of its container?

I have acheived this in JQuery by putting a zero width strut element above the float right, then sizing the strut (or pipe) according to parent height minus floated child's height.

Before js kicks in I am using the position absolute approach, which works but allows text flow behind. Therefore I switch to position static to enable the strut approach. (header is the parent element, cutout is the one i want bottom right, and pipe is my strut)

$("header .pipe").each(function(){
    $(this).next(".cutout").css("position","static");       
    $(this).height($(this).parent().height()-$(this).next(".cutout").height());                                                 
});

CSS

header{
    position: relative; 
}

header img.cutout{
    float:right;
    position:absolute;
    bottom:0;
    right:0;
    clear:right
}
header .pipe{
    width:0px; 
    float:right

}

The pipe must come 1st, then the cutout, then the text in the HTML order.

SQL Server convert string to datetime

UPDATE MyTable SET MyDate = CONVERT(datetime, '2009/07/16 08:28:01', 120)

For a full discussion of CAST and CONVERT, including the different date formatting options, see the MSDN Library Link below:

https://docs.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql

How do I run Java .class files?

This can mean a lot of things, but the most common one is that the class contained in the file doesn't have the same name as the file itself. So, check if your class is also called HelloWorld2.

How can I auto hide alert box after it showing it?

You can also try Notification API. Here's an example:

function message(msg){
    if (window.webkitNotifications) {
        if (window.webkitNotifications.checkPermission() == 0) {
        notification = window.webkitNotifications.createNotification(
          'picture.png', 'Title', msg);
                    notification.onshow = function() { // when message shows up
                        setTimeout(function() {
                            notification.close();
                        }, 1000); // close message after one second...
                    };
        notification.show();
      } else {
        window.webkitNotifications.requestPermission(); // ask for permissions
      }
    }
    else {
        alert(msg);// fallback for people who does not have notification API; show alert box instead
    }
    }

To use this, simply write:

message("hello");

Instead of:

alert("hello");

Note: Keep in mind that it's only currently supported in Chrome, Safari, Firefox and some mobile web browsers (jan. 2014)

Find supported browsers here.

Java stack overflow error - how to increase the stack size in Eclipse?

i also have the same problem while parsing schema definition files(XSD) using XSOM library,

i was able to increase Stack memory upto 208Mb then it showed heap_out_of_memory_error for which i was able to increase only upto 320mb.

the final configuration was -Xmx320m -Xss208m but then again it ran for some time and failed.

My function prints recursively the entire tree of the schema definition,amazingly the output file crossed 820Mb for a definition file of 4 Mb(Aixm library) which in turn uses 50 Mb of schema definition library(ISO gml).

with that I am convinced I have to avoid Recursion and then start iteration and some other way of representing the output, but I am having little trouble converting all that recursion to iteration.

Getting activity from context in android

  1. No
  2. You can't

There are two different contexts in Android. One for your application (Let's call it the BIG one) and one for each view (let's call it the activity context).

A linearLayout is a view, so you have to call the activity context. To call it from an activity, simply call "this". So easy isn't it?

When you use

this.getApplicationContext();

You call the BIG context, the one that describes your application and cannot manage your view.

A big problem with Android is that a context cannot call your activity. That's a big deal to avoid this when someone begins with the Android development. You have to find a better way to code your class (or replace "Context context" by "Activity activity" and cast it to "Context" when needed).

Regards.


Just to update my answer. The easiest way to get your Activity context is to define a static instance in your Activity. For example

public class DummyActivity extends Activity
{
    public static DummyActivity instance = null;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        // Do some operations here
    }

    @Override
    public void onResume()
    {
        super.onResume();
        instance = this;
    }

    @Override
    public void onPause()
    {
        super.onPause();
        instance = null;
    }
}

And then, in your Task, Dialog, View, you could use that kind of code to get your Activity context:

if (DummyActivity.instance != null)
{
    // Do your operations with DummyActivity.instance
}

How to store phone numbers on MySQL databases?

You can use varchar for storing phone numbers, so you need not remove the formatting

How to set a variable to current date and date-1 in linux?

You can also use the shorter format

From the man page:

%F     full date; same as %Y-%m-%d

Example:

#!/bin/bash
date_today=$(date +%F)
date_dir=$(date +%F -d yesterday)

React.js inline style best practices

There aren't a lot of "Best Practices" yet. Those of us that are using inline-styles, for React components, are still very much experimenting.

There are a number of approaches that vary wildly: React inline-style lib comparison chart

All or nothing?

What we refer to as "style" actually includes quite a few concepts:

  • Layout — how an element/component looks in relationship to others
  • Appearance — the characteristics of an element/component
  • Behavior and state — how an element/component looks in a given state

Start with state-styles

React is already managing the state of your components, this makes styles of state and behavior a natural fit for colocation with your component logic.

Instead of building components to render with conditional state-classes, consider adding state-styles directly:

// Typical component with state-classes
<li 
 className={classnames({ 'todo-list__item': true, 'is-complete': item.complete })} />


// Using inline-styles for state
<li className='todo-list__item'
 style={(item.complete) ? styles.complete : {}} />

Note that we're using a class to style appearance but no longer using any .is- prefixed class for state and behavior.

We can use Object.assign (ES6) or _.extend (underscore/lodash) to add support for multiple states:

// Supporting multiple-states with inline-styles
<li 'todo-list__item'
 style={Object.assign({}, item.complete && styles.complete, item.due && styles.due )}>

Customization and reusability

Now that we're using Object.assign it becomes very simple to make our component reusable with different styles. If we want to override the default styles, we can do so at the call-site with props, like so: <TodoItem dueStyle={ fontWeight: "bold" } />. Implemented like this:

<li 'todo-list__item'
 style={Object.assign({},
         item.due && styles.due,
         item.due && this.props.dueStyles)}>

Layout

Personally, I don't see compelling reason to inline layout styles. There are a number of great CSS layout systems out there. I'd just use one.

That said, don't add layout styles directly to your component. Wrap your components with layout components. Here's an example.

// This couples your component to the layout system
// It reduces the reusability of your component
<UserBadge
 className="col-xs-12 col-sm-6 col-md-8"
 firstName="Michael"
 lastName="Chan" />

// This is much easier to maintain and change
<div class="col-xs-12 col-sm-6 col-md-8">
  <UserBadge
   firstName="Michael"
   lastName="Chan" />
</div>

For layout support, I often try to design components to be 100% width and height.

Appearance

This is the most contentious area of the "inline-style" debate. Ultimately, it's up to the component your designing and the comfort of your team with JavaScript.

One thing is certain, you'll need the assistance of a library. Browser-states (:hover, :focus), and media-queries are painful in raw React.

I like Radium because the syntax for those hard parts is designed to model that of SASS.

Code organization

Often you'll see a style object outside of the module. For a todo-list component, it might look something like this:

var styles = {
  root: {
    display: "block"
  },
  item: {
    color: "black"

    complete: {
      textDecoration: "line-through"
    },

    due: {
      color: "red"
    }
  },
}

getter functions

Adding a bunch of style logic to your template can get a little messy (as seen above). I like to create getter functions to compute styles:

React.createClass({
  getStyles: function () {
    return Object.assign(
      {},
      item.props.complete && styles.complete,
      item.props.due && styles.due,
      item.props.due && this.props.dueStyles
    );
  },

  render: function () {
    return <li style={this.getStyles()}>{this.props.item}</li>
  }
});

Further watching

I discussed all of these in more detail at React Europe earlier this year: Inline Styles and when it's best to 'just use CSS'.

I'm happy to help as you make new discoveries along the way :) Hit me up -> @chantastic

using jquery $.ajax to call a PHP function

I would stick with normal approach to call the file directly, but if you really want to call a function, have a look at JSON-RPC (JSON Remote Procedure Call).

You basically send a JSON string in a specific format to the server, e.g.

{ "method": "echo", "params": ["Hello JSON-RPC"], "id": 1}

which includes the function to call and the parameters of that function.

Of course the server has to know how to handle such requests.
Here is jQuery plugin for JSON-RPC and e.g. the Zend JSON Server as server implementation in PHP.


This might be overkill for a small project or less functions. Easiest way would be karim's answer. On the other hand, JSON-RPC is a standard.

Could not autowire field in spring. why?

Well there's a problem with the creation of the ContactServiceImpl bean. First, make sure that the class is actually instantiated by debugging the no-args constructor when the Spring context is initiated and when an instance of ContactController is created.

If the ContactServiceImpl is actually instantiated by the Spring context, but it's simply not matched against your @Autowire annotation, try being more explicit in your annotation injection. Here's a guy dealing with a similar problem as yours and giving some possible solutions:

http://blogs.sourceallies.com/2011/08/spring-injection-with-resource-and-autowired/

If you ask me, I think you'll be ok if you replace

@Autowired
private ContactService contactService;

with:

@Resource
@Qualifier("contactService")
private ContactService contactService;

How do I get the unix timestamp in C as an int?

#include <stdio.h>
#include <time.h>

int main ()
{
   time_t seconds;

   seconds = time(NULL);
   printf("Seconds since January 1, 1970 = %ld\n", seconds);

   return(0);
}

And will get similar result:
Seconds since January 1, 1970 = 1476107865

Set CFLAGS and CXXFLAGS options using CMake

The easiest solution working fine for me is this:

export CFLAGS=-ggdb
export CXXFLAGS=-ggdb

CMake will append them to all configurations' flags. Just make sure to clear CMake cache.

Printing Batch file results to a text file

For showing result of batch file in text file, you can use

this command

chdir > test.txt

This command will redirect result to test.txt.

When you open test.txt you will found current path of directory in test.txt

Javascript: best Singleton pattern

Why use a constructor and prototyping for a single object?

The above is equivalent to:

var earth= {
    someMethod: function () {
        if (console && console.log)
            console.log('some method');                             
    }
};
privateFunction1();
privateFunction2();

return {
    Person: Constructors.Person,
    PlanetEarth: earth
};

"call to undefined function" error when calling class method

Another silly mistake you can do is copy recursive function from non class environment to class and don`t change inner self calls to $this->method_name()

i`m writing this because couldn`t understand why i got this error and this thread is first in google when you search for this error.

jQuery 'if .change() or .keyup()'

you can bind to multiple events by separating them with a space:

$(":input").on("keyup change", function(e) {
    // do stuff!
})

docs here.

hope that helps. cheers!

Import a module from a relative path

import os
import sys
lib_path = os.path.abspath(os.path.join(__file__, '..', '..', '..', 'lib'))
sys.path.append(lib_path)

import mymodule

org.postgresql.util.PSQLException: FATAL: sorry, too many clients already

The offending lines are the following:

MaxConnections=90
InitialConnections=80

You can increase the values to allow more connections.

Install mysql-python (Windows)

For folks using Python 3.0+ (which should be everyone now):

Unfortunately, MySQL-Python 1.2.5 does not support Python 3.0+ yet (which is kinda unreasonable IMHO, Python 3+ has been out for a while). Reference : https://pypi.python.org/pypi/MySQL-python/1.2.5

So, my workaround is to use Oracle's MySQL connector. In settings.py, change DATABASE's 'ENGINE' field to: 'ENGINE': 'mysql.connector.django',

More info could be found in the last paragraph of the first answer to this question: Setting Django up to use MySQL

Hope this helps!!

Launching Spring application Address already in use

This error basically happens when the specific port is not free. So there are two solutions, you can free that port by killing or closing the service which is using it or you can run your application (tomcat) on a different port.

Solution 1: Free the port

On a Linux machine you can find the process-id of port's consumer and then kill it. Use the following command (it is assume that the default port is 8080)

netstat -pnltu | grep -i "8080"

The output of the above-mentioned command would be something like:

tcp6   0  0 :::8080    :::*      LISTEN      20674/java 

Then you can easily kill the process with its processid:

kill 20674

On a windows machine to find a processid use netstat -ano -p tcp |find "8080". To kill the process use taskkill /F /PID 1234 (instead of 1234 enter the founded processid).

Solution 2: Change the default port

In the development process developers use the port 8080 that you can change it easily. You need to specify your desired port number in the application.properties file of your project (/src/main/resources/application.properties) by using the following specification:

server.port=8081

You can also set an alternative port number while executing the .jar file

- java -jar spring-boot-application.jar --server.port=8081

Please notice that sometimes (not necessarily) you have to change other ports too like:

management.port=
tomcat.jvmroute=
tomcat.ajp.port=
tomcat.ajp.redirectPort=
etc...

How to get ID of clicked element with jQuery

Your id will be passed through as #1, #2 etc. However, # is not valid as an ID (CSS selectors prefix IDs with #).

send/post xml file using curl command line

You can use this command:

curl -X POST --header 'Content-Type: multipart/form-data' --header 'Accept: application/json' --header 'Authorization: <<Removed>>' -F file=@"/home/xxx/Desktop/customers.json"  'API_SERVER_URL' -k 

Is there a way to "limit" the result with ELOQUENT ORM of Laravel?

Also, we can use it following ways

To get only first

 $cat_details = DB::table('an_category')->where('slug', 'people')->first();

To get by limit and offset

$top_articles = DB::table('an_pages')->where('status',1)->limit(30)->offset(0)->orderBy('id', 'DESC')->get();
$remaining_articles = DB::table('an_pages')->where('status',1)->limit(30)->offset(30)->orderBy('id', 'DESC')->get();

sql server #region

(I am developer of SSMSBoost add-in for SSMS)

We have recently added support for this syntax into our SSMSBoost add-in.

--#region [Optional Name]
--#endregion

It has also an option to automatically "recognize" regions when opening scripts.

How can I make a program wait for a variable change in javascript?

Super dated, but certainly good ways to accomodate this. Just wrote this up for a project and figured I'd share. Similar to some of the others, varied in style.

var ObjectListener = function(prop, value) {

  if (value === undefined) value = null;

  var obj = {};    
  obj.internal = value;
  obj.watcher = (function(x) {});
  obj.emit = function(fn) {
    obj.watch = fn;
  };

  var setter = {};
  setter.enumerable = true;
  setter.configurable = true;
  setter.set = function(x) {
    obj.internal = x;
    obj.watcher(x);
  };

  var getter = {};
  getter.enumerable = true;
  getter.configurable = true;
  getter.get = function() {
    return obj.internal;
  };

  return (obj,
    Object.defineProperty(obj, prop, setter),
    Object.defineProperty(obj, prop, getter),
    obj.emit, obj);

};


user._licenseXYZ = ObjectListener(testProp);
user._licenseXYZ.emit(testLog);

function testLog() {
  return function() {
    return console.log([
        'user._licenseXYZ.testProp was updated to ', value
    ].join('');
  };
}


user._licenseXYZ.testProp = 123;

ImportError: No module named sklearn.cross_validation

Splitting the dataset into the Training set and Test set

from sklearn.model_selection import train_test_split

How to set 24-hours format for date on java?

Use HH instead of hh in formatter string

Visual Studio C# IntelliSense not automatically displaying

I simply closed all pages of visual studio and reopened ..it worked.

error: request for member '..' in '..' which is of non-class type

I ran into a case where I got that error message and had

Foo foo(Bar());

and was basically trying to pass in a temporary Bar object to the Foo constructor. Turns out the compiler was translating this to

Foo foo(Bar(*)());

that is, a function declaration whose name is foo that returns a Foo that takes in an argument -- a function pointer returning a Bar with 0 arguments. When passing in temporaries like this, better to use Bar{} instead of Bar() to eliminate ambiguity.

How to make correct date format when writing data to Excel

This worked for me:

hoja_trabajo.Cells[i + 2, j + 1] = fecha.ToString("dd-MMM-yyyy").Replace(".", "");

How can I pass a parameter to a Java Thread?

In Java 8 you can use lambda expressions with the Concurrency API & the ExecutorService as a higher level replacement for working with threads directly:

newCachedThreadPool() Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available. These pools will typically improve the performance of programs that execute many short-lived asynchronous tasks.

    private static final ExecutorService executor = Executors.newCachedThreadPool();

    executor.submit(() -> {
        myFunction(myParam1, myParam2);
    });

See also executors javadocs.

MySQL - Meaning of "PRIMARY KEY", "UNIQUE KEY" and "KEY" when used together while creating a table

Just to add to the other answers, the documentation gives this explanation:

  • KEY is normally a synonym for INDEX. The key attribute PRIMARY KEY can also be specified as just KEY when given in a column definition. This was implemented for compatibility with other database systems.

  • A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL.

  • A PRIMARY KEY is a unique index where all key columns must be defined as NOT NULL. If they are not explicitly declared as NOT NULL, MySQL declares them so implicitly (and silently). A table can have only one PRIMARY KEY. The name of a PRIMARY KEY is always PRIMARY, which thus cannot be used as the name for any other kind of index.

How can I stop "property does not exist on type JQuery" syntax errors when using Typescript?

You can cast it to

(<any>$('.selector') ).function();

Ex: date picker initialize using jquery

(<any>$('.datepicker') ).datepicker();

How do you recursively unzip archives in a directory and its subdirectories from the Unix command-line?

I realise this is very old, but it was among the first hits on Google when I was looking for a solution to something similar, so I'll post what I did here. My scenario is slightly different as I basically just wanted to fully explode a jar, along with all jars contained within it, so I wrote the following bash functions:

function explode {
    local target="$1"
    echo "Exploding $target."
    if [ -f "$target" ] ; then
        explodeFile "$target"
    elif [ -d "$target" ] ; then
        while [ "$(find "$target" -type f -regextype posix-egrep -iregex ".*\.(zip|jar|ear|war|sar)")" != "" ] ; do
            find "$target" -type f -regextype posix-egrep -iregex ".*\.(zip|jar|ear|war|sar)" -exec bash -c 'source "<file-where-this-function-is-stored>" ; explode "{}"' \;
        done
    else
        echo "Could not find $target."
    fi
}

function explodeFile {
    local target="$1"
    echo "Exploding file $target."
    mv "$target" "$target.tmp"
    unzip -q "$target.tmp" -d "$target"
    rm "$target.tmp"
}

Note the <file-where-this-function-is-stored> which is needed if you're storing this in a file that is not read for a non-interactive shell as I happened to be. If you're storing the functions in a file loaded on non-interactive shells (e.g., .bashrc I believe) you can drop the whole source statement. Hopefully this will help someone.

A little warning - explodeFile also deletes the ziped file, you can of course change that by commenting out the last line.

What does this GCC error "... relocation truncated to fit..." mean?

I ran into the exact same issue. After compiling without the -fexceptions build flag, the file compiled with no issue

Why don't Java's +=, -=, *=, /= compound assignment operators require casting?

The problem here involves type casting.

When you add int and long,

  1. The int object is casted to long & both are added and you get long object.
  2. but long object cannot be implicitly casted to int. So, you have to do that explicitly.

But += is coded in such a way that it does type casting. i=(int)(i+m)

Set Session variable using javascript in PHP

I solved this question using Ajax. What I do is make an ajax call to a PHP page where the value that passes will be saved in session.

The example that I am going to show you, what I do is that when you change the value of the number of items to show in a datatable, that value is saved in session.

$('#table-campus').on( 'length.dt', function ( e, settings, len ) {
    $.ajax ({
       data:        {"numElems": len},
       url:        '../../Utiles/GuardarNumElems.php',
       type:        'post'
    }); 
});

And the GuardarNumElems.php is as following:

<?php    
    session_start();

    if(isset ($_POST['numElems'] )){
        $numElems = $_POST['numElems'];        
        $_SESSION['elems_table'] = $numElems;
    }else{
        $_SESSION['elems_table'] = 25;
    } 
?>

A simple jQuery form validation script

you can use jquery validator for that but you need to add jquery.validate.js and jquery.form.js file for that. after including validator file define your validation something like this.

<script type="text/javascript">
$(document).ready(function(){
    $("#formID").validate({
    rules :{
        "data[User][name]" : {
            required : true
        }
    },
    messages :{
        "data[User][name]" : {
            required : 'Enter username'
        }
    }
    });
});
</script>

You can see required : true same there is many more property like for email you can define email : true for number number : true

What is the opposite of evt.preventDefault();

This is what I used to set it:

$("body").on('touchmove', function(e){ 
    e.preventDefault(); 
});

And to undo it:

$("body").unbind("touchmove");

How should I read a file line-by-line in Python?

Yes,

with open('filename.txt') as fp:
    for line in fp:
        print line

is the way to go.

It is not more verbose. It is more safe.

How to check if a service is running via batch file and start it, if it is not running?

Maybe a much simpler way? Just adding to the list of answers here:

@for /f "tokens=1,* delims=: " %%a in ('sc queryex state=Inactive') do net start "%%b"

adb shell command to make Android package uninstall dialog appear

While the above answers work but in case you have multiple devices connected to your computer then the following command can be used to remove the app from one of them:

adb -s <device-serial> shell pm uninstall <app-package-name>

If you want to find out the device serial then use the following command:

adb devices -l

This will give you a list of devices attached. The left column shows the device serials.

How do I deal with "signed/unsigned mismatch" warnings (C4018)?

I had a similar problem. Using size_t was not working. I tried the other one which worked for me. (as below)

for(int i = things.size()-1;i>=0;i--)
{
 //...
}

Http Get using Android HttpURLConnection

A more contemporary way of doing it on a separate thread using Tasks and Kotlin

private val mExecutor: Executor = Executors.newSingleThreadExecutor()

private fun createHttpTask(u:String): Task<String> {
    return Tasks.call(mExecutor, Callable<String>{
        val url = URL(u)
        val conn: HttpURLConnection = url.openConnection() as HttpURLConnection
        conn.requestMethod = "GET"
        conn.connectTimeout = 3000
        conn.readTimeout = 3000
        val rc = conn.responseCode
        if ( rc != HttpURLConnection.HTTP_OK) {
            throw java.lang.Exception("Error: ${rc}")
        }
        val inp: InputStream = BufferedInputStream(conn.inputStream)
        val resp: String = inp.bufferedReader(UTF_8).use{ it.readText() }
        return@Callable resp
    })
}

and now you can use it like below in many places:

            createHttpTask("https://google.com")
                    .addOnSuccessListener {
                        Log.d("HTTP", "Response: ${it}") // 'it' is a response string here
                    }
                    .addOnFailureListener {
                        Log.d("HTTP", "Error: ${it.message}") // 'it' is an Exception object here
                    }

What's the difference between & and && in MATLAB?

A good rule of thumb when constructing arguments for use in conditional statements (IF, WHILE, etc.) is to always use the &&/|| forms, unless there's a very good reason not to. There are two reasons...

  1. As others have mentioned, the short-circuiting behavior of &&/|| is similar to most C-like languages. That similarity / familiarity is generally considered a point in its favor.
  2. Using the && or || forms forces you to write the full code for deciding your intent for vector arguments. When a = [1 0 0 1] and b = [0 1 0 1], is a&b true or false? I can't remember the rules for MATLAB's &, can you? Most people can't. On the other hand, if you use && or ||, you're FORCED to write the code "in full" to resolve the condition.

Doing this, rather than relying on MATLAB's resolution of vectors in & and |, leads to code that's a little bit more verbose, but a LOT safer and easier to maintain.

Boolean checking in the 'if' condition

My personal feeling when it comes to reading

if(!status) : if not status

if(status == false) : if status is false

if you are not used to !status reading. I see no harm doing as the second way.

if you use "active" instead of status I thing if(!active) is more readable

setting multiple column using one update

Just add parameters, split by comma:

UPDATE tablename SET column1 = "value1", column2 = "value2" ....

See also: mySQL manual on UPDATE

android: changing option menu items programmatically

Like Nikolay said do that in onPrepareOptionsMenu().

For menu items in the action bar you have to invalidate the menu with activity.invalidateOptionsMenu();

This is descriped in more detail here How can I refresh the ActionBar when onPrepareOptionsMenu switched menu entries?

Mongodb service won't start

I tried deleting the lock file, but the real reason that this happened to me was because I was using ~/data/db as the data directory. Mongo needs an absolute path to the database. Once I changed it to /home//data/db, I was in business.

Limitations of SQL Server Express

Another limitation to consider is that SQL Server Express editions go into an idle mode after a period of disuse.

Understanding SQL Express behavior: Idle time resource usage, AUTO_CLOSE and User Instances:

When SQL Express is idle it aggressively trims back the working memory set by writing the cached data back to disk and releasing the memory.

But this is easily worked around: Is there a way to stop SQL Express 2008 from Idling?

How to run Node.js as a background process and never die?

$ disown node server.js &

It will remove command from active task list and send the command to background

Python: For each list element apply a function across the list

Some readable python:

def JoeCalimar(l):
    masterList = []
    for i in l:
        for j in l:
            masterList.append(1.*i/j)
    pos = masterList.index(min(masterList))
    a = pos/len(masterList)
    b = pos%len(masterList)
    return (l[a],l[b])

Let me know if something is not clear.

Convert text to columns in Excel using VBA

If someone is facing issue using texttocolumns function in UFT. Please try using below function.

myxl.Workbooks.Open myexcel.xls
myxl.Application.Visible = false `enter code here`
set mysheet = myxl.ActiveWorkbook.Worksheets(1)
Set objRange = myxl.Range("A1").EntireColumn
Set objRange2 = mysheet.Range("A1")
objRange.TextToColumns objRange2,1,1, , , , true

Here we are using coma(,) as delimiter.

How can I stop .gitignore from appearing in the list of untracked files?

The .gitignore file should be in your repository, so it should indeed be added and committed in, as git status suggests. It has to be a part of the repository tree, so that changes to it can be merged and so on.

So, add it to your repository, it should not be gitignored.

If you really want you can add .gitignore to the .gitignore file if you don't want it to be committed. However, in that case it's probably better to add the ignores to .git/info/exclude, a special checkout-local file that works just like .gitignore but does not show up in "git status" since it's in the .git folder.

See also https://help.github.com/articles/ignoring-files

How can I strip first X characters from string using sed?

Another way, using cut instead of sed.

result=`echo $pid | cut -c 5-`

How to sort rows of HTML table that are called from MySQL

//this is a php file

<html>
<head>
<style>
a:link {color:green;}
a:visited {color:purple;}
A:active {color: red;}
A:hover {color: red;}
table
{
    width:50%;
    height:50%;
}
table,th,td
{
    border:1px solid black;
}
th,td
{
    text-align:center;  
    background-color:yellow;
}
th
{
    background-color:green;
    color:white;    
}
</style>
<script type="text/javascript">
function working(str)
{
if (str=="")
  {
  document.getElementById("tump").innerHTML="";
  return;
  } 
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("tump").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","getsort.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body bgcolor="pink">
<form method="post">
<select name="sortitems" onchange="working(this.value)">
<option value="">Select</option>
<option value="Id">Id</option>
<option value="Name">Name</option>
<option value="Email">Email</option>
<option value="Password">Password</option>
</select>
<?php 
$connect=mysql_connect("localhost","root","");
$db=mysql_select_db("test1",$connect);
$sql=mysql_query("select * from mine");
echo "<center><br><br><br><br><table id='tump' border='1'>
<tr>
<th>Id</th>
<th>Name</th>
<th>Email</th>
<th>Password</th>
</tr>";
echo "<tr>";
while ($row=mysql_fetch_array($sql))
{?>
<td><?php echo "$row[Id]";?></td>
<td><?php echo "$row[Name]";?></td>
<td><?php echo "$row[Email]";?></td>
<td><?php echo "$row[Password]";?></td>
<?php echo "</tr>";
}
echo "</table></center>";?>
</form>
<br>
<div id="tump"></div>
</body>
</html>
------------------------------------------------------------------------
that is another php file

<html>
<body bgcolor="pink">
<head>
<style>
a:link {color:green;}
a:visited {color:purple;}
A:active {color: red;}
A:hover {color: red;}
table
{
    width:50%;
    height:50%;
}
table,th,td
{
    border:1px solid black;
}
th,td
{
    text-align:center;  
    background-color:yellow;
}
th
{
    background-color:green;
    color:white;    
}
</style>
</head>
<?php
$q=$_GET['q'];
$connect=mysql_connect("localhost","root","");
$db=mysql_select_db("test1",$connect);
$sql=mysql_query("select * from mine order by $q");
echo "<table id='tump' border='1'>
<tr>
<th>Id</th>
<th>Name</th>
<th>Email</th>
<th>Password</th>
</tr>";
echo "<tr>";
while ($row=mysql_fetch_array($sql))
{?>
<td><?php echo "$row[Id]";?></td>
<td><?php echo "$row[Name]";?></td>
<td><?php echo "$row[Email]";?></td>
<td><?php echo "$row[Password]";?></td>
<?php echo "</tr>";
}
echo "</table>";?>
</body>
</html>



that will sort the table using ajax

Difference between <span> and <div> with text-align:center;?

It might be, because your span element sets is side as width as its content. if you have a div with 500px width and text-align center, and you enter a span tag it should be aligned in the center. So your problem might be a CSS one. Install Firebug at Firefox and check the style attributes your span or div object has.

Autoplay audio files on an iPad with HTML5

Apple does not support the standard completely, but there is a workaround. Their justification is cellular network congestion, maybe because you'll land on pages that play random audio. This behavior doesn't change when a device goes on wifi, maybe for consistency. By the way, those pages are usually a bad idea anyway. You should not be trying to put a soundtrack on every web page. That's just wrong. :)

html5 audio will play if it is started as the result of a user action. Loading a page does not count. So you need to restructure your web app to be an all-in-one-page app. Instead of a link that opens a page that plays audio, you need that link to play it on the current page, without a page change. This "user interaction" rule applies to the html5 methods you can call on an audio or video element. The calls return without any effect if they are fired automatically on page load, but they work when called from event handlers.

Prevent a webpage from navigating away using JavaScript

Use onunload.

For jQuery, I think this works like so:

$(window).unload(function() { 
  alert("Unloading"); 
  return falseIfYouWantToButBeCareful();
});

How to use Comparator in Java to sort

Here's an example of a Comparator that will work for any zero arg method that returns a Comparable. Does something like this exist in a jdk or library?

import java.lang.reflect.Method;
import java.util.Comparator;

public class NamedMethodComparator implements Comparator<Object> {

    //
    // instance variables
    //

    private String methodName;

    private boolean isAsc;

    //
    // constructor
    //

    public NamedMethodComparator(String methodName, boolean isAsc) {
        this.methodName = methodName;
        this.isAsc = isAsc;
    }

    /**
     * Method to compare two objects using the method named in the constructor.
     */
    @Override
    public int compare(Object obj1, Object obj2) {
        Comparable comp1 = getValue(obj1, methodName);
        Comparable comp2 = getValue(obj2, methodName);
        if (isAsc) {
            return comp1.compareTo(comp2);
        } else {
            return comp2.compareTo(comp1);
        }
    }

    //
    // implementation
    //

    private Comparable getValue(Object obj, String methodName) {
        Method method = getMethod(obj, methodName);
        Comparable comp = getValue(obj, method);
        return comp;
    }

    private Method getMethod(Object obj, String methodName) {
        try {
            Class[] signature = {};
            Method method = obj.getClass().getMethod(methodName, signature);
            return method;
        } catch (Exception exp) {
            throw new RuntimeException(exp);
        }
    }

    private Comparable getValue(Object obj, Method method) {
        Object[] args = {};
        try {
            Object rtn = method.invoke(obj, args);
            Comparable comp = (Comparable) rtn;
            return comp;
        } catch (Exception exp) {
            throw new RuntimeException(exp);
        }
    }

}

Android Studio - How to Change Android SDK Path

  1. Click on File menu.
  2. Select Project Structure.
  3. Edit the path in SDK Location text box. From the next time Android Studio will use this location for all your projects.

N.B.: Avoid having spaces in the path as it may sometimes lead to issues.

How can I specify a local gem in my Gemfile?

If you want the branch too:

gem 'foo', path: "point/to/your/path", branch: "branch-name"

How to return rows from left table not found in right table?

I also like to use NOT EXISTS. When it comes to performance if index correctly it should perform the same as a LEFT JOIN or better. Plus its easier to read.

SELECT Column1
FROM TableA a
WHERE NOT EXISTS ( SELECT Column1
                   FROM Tableb b
                   WHERE a.Column1 = b.Column1
                 )

How to empty/destroy a session in rails?

session in rails is a hash object. Hence any function available for clearing hash will work with sessions.

session.clear

or if specific keys have to be destroyed:

session.delete(key)

Tested in rails 3.2

added

People have mentioned by session={} is a bad idea. Regarding session.clear, Lobati comments- It looks like you're probably better off using reset_session [than session.clear], as it does some other cleaning up beyond what session.clear does. Internally, reset_session calls session.destroy, which itself calls clear as well some other stuff.

What certificates are trusted in truststore?

Trust store generally (actually should only contain root CAs but this rule is violated in general) contains the certificates that of the root CAs (public CAs or private CAs). You can verify the list of certs in trust store using

keytool -list -v -keystore truststore.jks

Can linux cat command be used for writing text to file?

simply pipeline echo with cat

For example

echo write something to file.txt | cat > file.txt

Change string color with NSAttributedString?

Update for Swift 4.2

var attributes = [NSAttributedString.Key: AnyObject]()

attributes[.foregroundColor] = UIColor.blue

let attributedString = NSAttributedString(string: "Very Bad",
attributes: attributes)

label.attributedText = attributedString

Text overflow ellipsis on two lines

Easy CSS properties can do the trick. The following is for a three-line ellipsis.

display: -webkit-box;
-webkit-line-clamp: 3;
-webkit-box-orient: vertical;
overflow: hidden;
text-overflow: ellipsis;

Activity transition in Android

Yes. You can tell the OS what kind of transition you want to have for your activity.

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    getWindow().setWindowAnimations(ANIMATION);

    ...

}

Where ANIMATION is an integer referring to a built in animation in the OS.

How to redirect to another page in node.js

In another way you can use window.location.href="your URL"

e.g.:

res.send('<script>window.location.href="your URL";</script>');

or:

return res.redirect("your url");

Finding common rows (intersection) in two Pandas dataframes

If I understand you correctly, you can use a combination of Series.isin() and DataFrame.append():

In [80]: df1
Out[80]:
   rating  user_id
0       2  0x21abL
1       1  0x21abL
2       1   0xdafL
3       0  0x21abL
4       4  0x1d14L
5       2  0x21abL
6       1  0x21abL
7       0   0xdafL
8       4  0x1d14L
9       1  0x21abL

In [81]: df2
Out[81]:
   rating      user_id
0       2      0x1d14L
1       1    0xdbdcad7
2       1      0x21abL
3       3      0x21abL
4       3      0x21abL
5       1  0x5734a81e2
6       2      0x1d14L
7       0       0xdafL
8       0      0x1d14L
9       4  0x5734a81e2

In [82]: ind = df2.user_id.isin(df1.user_id) & df1.user_id.isin(df2.user_id)

In [83]: ind
Out[83]:
0     True
1    False
2     True
3     True
4     True
5    False
6     True
7     True
8     True
9    False
Name: user_id, dtype: bool

In [84]: df1[ind].append(df2[ind])
Out[84]:
   rating  user_id
0       2  0x21abL
2       1   0xdafL
3       0  0x21abL
4       4  0x1d14L
6       1  0x21abL
7       0   0xdafL
8       4  0x1d14L
0       2  0x1d14L
2       1  0x21abL
3       3  0x21abL
4       3  0x21abL
6       2  0x1d14L
7       0   0xdafL
8       0  0x1d14L

This is essentially the algorithm you described as "clunky", using idiomatic pandas methods. Note the duplicate row indices. Also, note that this won't give you the expected output if df1 and df2 have no overlapping row indices, i.e., if

In [93]: df1.index & df2.index
Out[93]: Int64Index([], dtype='int64')

In fact, it won't give the expected output if their row indices are not equal.

How to set a border for an HTML div tag

In bootstrap 4, you can use border utilities like so.

_x000D_
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" rel="stylesheet" />_x000D_
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js"></script>_x000D_
_x000D_
<style>_x000D_
  .border-5 {_x000D_
    border-width: 5px !important;_x000D_
  }_x000D_
</style>_x000D_
_x000D_
<textarea class="border border-dark border-5">some content</textarea>
_x000D_
_x000D_
_x000D_

How to join two sets in one line without using "|"

You can do union or simple list comprehension

[A.add(_) for _ in B]

A would have all the elements of B

GROUP BY and COUNT in PostgreSQL

I think you just need COUNT(DISTINCT post_id) FROM votes.

See "4.2.7. Aggregate Expressions" section in http://www.postgresql.org/docs/current/static/sql-expressions.html.

EDIT: Corrected my careless mistake per Erwin's comment.

How to match all occurrences of a regex

Using scan should do the trick:

string.scan(/regex/)

Magento - How to add/remove links on my account navigation?

Open navigation.phtml

app/design/frontend/yourtheme/default/template/customer/account/navigation.phtml

replace

<?php $_links = $this->getLinks(); ?>

with unset link which you want to remove

<?php 
$_count = count($_links);
unset($_links['account']); // Account Information     
unset($_links['account_edit']); // Account Information  
unset($_links['address_book']); // Address Book
unset($_links['orders']); // My Orders
unset($_links['billing_agreements']); // Billing Agreements
unset($_links['recurring_profiles']); // Recurring Profiles
unset($_links['reviews']);  // My Product Reviews
unset($_links['wishlist']); // My Wishlist
unset($_links['OAuth Customer Tokens']); // My Applications
unset($_links['newsletter']); // Newsletter Subscriptions
unset($_links['downloadable_products']); // My Downloadable Products
unset($_links['tags']); // My Tags
unset($_links['invitations']); // My Invitations
unset($_links['enterprise_customerbalance']); // Store Credit
unset($_links['enterprise_reward']); // Reward Points
unset($_links['giftregistry']); // Gift Registry
unset($_links['enterprise_giftcardaccount']); // Gift Card Link
?>

How do I parse JSON into an int?

I use a combination of json.get() and instanceof to read in values that might be either integers or integer strings.

These three test cases illustrate:

int val;
Object obj;
JSONObject json = new JSONObject();
json.put("number", 1);
json.put("string", "10");
json.put("other", "tree");

obj = json.get("number");
val = (obj instanceof Integer) ? (int) obj : (int) Integer.parseInt((String) obj);
System.out.println(val);

obj = json.get("string");
val = (obj instanceof Integer) ? (int) obj : (int) Integer.parseInt((String) obj);
System.out.println(val);

try {
    obj = json.get("other");
    val = (obj instanceof Integer) ? (int) obj : (int) Integer.parseInt((String) obj);
} catch (Exception e) {
    // throws exception
}

Android WebView, how to handle redirects in app instead of opening a browser

@Override
public void onPageStarted(WebView view, String url, Bitmap favicon) {
    super.onPageStarted(view, url, favicon);
    if (url.equals("your url")) {
        
            Intent intent = new Intent(view.getContext(), TransferAllDoneActivity.class);
            startActivity(intent);
        
    }
}

Where to put Gradle configuration (i.e. credentials) that should not be committed?

If you have user specific credentials ( i.e each developer might have different username/password ) then I would recommend using the gradle-properties-plugin.

  1. Put defaults in gradle.properties
  2. Each developer overrides with gradle-local.properties ( this should be git ignored ).

This is better than overriding using $USER_HOME/.gradle/gradle.properties because different projects might have same property names.

How to printf uint64_t? Fails with: "spurious trailing ‘%’ in format"

The ISO C99 standard specifies that these macros must only be defined if explicitly requested.

#define __STDC_FORMAT_MACROS
#include <inttypes.h>

... now PRIu64 will work

WHERE clause on SQL Server "Text" data type

If you can't change the datatype on the table itself to use varchar(max), then change your query to this:

SELECT *
FROM   [Village]
WHERE  CONVERT(VARCHAR(MAX), [CastleType]) = 'foo'

MongoDB not equal to

If there is a null in an array and you want to avoid it:

db.test.find({"contain" : {$ne :[] }}).pretty()

rsync: difference between --size-only and --ignore-times

You are missing that rsync can also compare files by checksum.

--size-only means that rsync will skip files that match in size, even if the timestamps differ. This means it will synchronise fewer files than the default behaviour. It will miss any file with changes that don't affect the overall file size. If you have something that changes the dates on files without changing the files, and you don't want rsync to spend lots of time checksumming those files to discover they haven't changed, this is the option to use.

--ignore-times means that rsync will checksum every file, even if the timestamps and file sizes match. This means it will synchronise more files than the default behaviour. It will include changes to files even where the file size is the same and the modification date/time has been reset to the original value. Checksumming every file means it has to be entirely read from disk, which may be slow. Some build pipelines will reset timestamps to a specific date (like 1970-01-01) to ensure that the final build file is reproducible bit for bit, e.g. when packed into a tar file that saves the timestamps.

Moment JS start and end of given month

const dates = getDatesFromDateRange("2014-05-02", "2018-05-12", "YYYY/MM/DD", 1);           
console.log(dates);
// you get the whole from-to date ranges as per parameters
var onlyStartDates = dates.map(dateObj => dateObj["to"]);
console.log(onlyStartDates);
// moreover, if you want only from dates then you can grab by "map" function

function getDatesFromDateRange( startDate, endDate, format, counter ) {
    startDate = moment(startDate, format);
    endDate = moment(endDate, format);

    let dates = [];
    let fromDate = startDate.clone();
    let toDate = fromDate.clone().add(counter, "month").startOf("month").add(-1, "day");
    do {
        dates.push({
            "from": fromDate.format(format),
            "to": ( toDate < endDate ) ? toDate.format(format) : endDate.format(format)
        });
        fromDate = moment(toDate, format).add(1, "day").clone();
        toDate = fromDate.clone().add(counter, "month").startOf("month").add(-1, "day");
    } while ( fromDate < endDate );
    return dates;
}

Please note, .clone() is essential in momentjs else it'll override the value. It seems in your case.

It's more generic, to get bunch of dates that fall between dates.

Read XLSX file in Java

AFAIK there are no xlsx-libraries available yet. But there are some for old xls:

One library is jxls which internally uses the already mentioned POI.

2 other links: Handle Excel files, Java libraries to read and write Excel XLS document files.

AWS EFS vs EBS vs S3 (differences & when to use?)

To add to the comparison: (burst)read/write-performance on EFS depends on gathered credits. Gathering of credits depends on the amount of data you store on it. More date -> more credits. That means that when you only need a few GB of storage which is read or written often you will run out of credits very soon and througphput drops to about 50kb/s. The only way to fix this (in my case) was to add large dummy files to increase the rate credits are earned. However more storage -> more cost.

onClick function of an input type="button" not working

You have to change the ID of the button to be different from the function name JSFiddle

_x000D_
_x000D_
var counter = 0;_x000D_
_x000D_
_x000D_
function moreFields() {_x000D_
  counter++;_x000D_
  var newFields = document.getElementById('readroot').cloneNode(true);_x000D_
  newFields.id = '';_x000D_
  newFields.style.display = 'block';_x000D_
  var newField = newFields.childNodes;_x000D_
  for (var i = 0; i < newField.length; i++) {_x000D_
    var theName = newField[i].name_x000D_
    if (theName) newField[i].name = theName + counter;_x000D_
  }_x000D_
  var insertHere = document.getElementById('writeroot');_x000D_
  insertHere.parentNode.insertBefore(newFields, insertHere);_x000D_
}_x000D_
_x000D_
window.onload = moreFields();
_x000D_
<div id="readroot" style="display: none">_x000D_
  <input type="button" value="Remove review" onclick="this.parentNode.parentNode.removeChild(this.parentNode);" />_x000D_
  <br />_x000D_
  <br />_x000D_
  <input name="cd" value="title" />_x000D_
  <select name="rankingsel">_x000D_
    <option>Rating</option>_x000D_
    <option value="excellent">Excellent</option>_x000D_
    <option value="good">Good</option>_x000D_
    <option value="ok">OK</option>_x000D_
    <option value="poor">Poor</option>_x000D_
    <option value="bad">Bad</option>_x000D_
  </select>_x000D_
  <br />_x000D_
  <br />_x000D_
  <textarea rows="5" cols="20" name="review">Short review</textarea>_x000D_
  <br />Radio buttons included to test them in Explorer:_x000D_
  <br />_x000D_
  <input type="radio" name="something" value="test1" />Test 1_x000D_
  <br />_x000D_
  <input type="radio" name="something" value="test2" />Test 2</div>_x000D_
<form method="post" action="index1.php"> <span id="writeroot"></span>_x000D_
_x000D_
  <input type="button" onclick="moreFields();" id="moreFieldsButton" value="Give me more fields!" />_x000D_
  <input type="submit" value="Send form" />_x000D_
</form>
_x000D_
_x000D_
_x000D_

Cut Java String at a number of character

Jakarta Commons StringUtils.abbreviate(). If, for some reason you don't want to use a 3rd-party library, at least copy the source code.

One big benefit of this over the other answers to date is that it won't throw if you pass in a null.

SSL Connection / Connection Reset with IISExpress

In my case, I was getting this exact error running on port 443, and (for reasons I won't go into here) switching to a different port was not an option. In order to get IIS Express to work on port 443, I had to run this command...

C:\Program Files\IIS Express>IisExpressAdminCmd.exe setupsslUrl -url:https://localhost:443/ -UseSelfSigned

Much thanks to Robert Muehsig for originally posting this solution here.

https://blog.codeinside.eu/2018/10/31/fix-ERR_CONNECTION_RESET-and-ERR_CERT_AUTHORITY_INVALID-with-iisexpress-and-ssl/

How to open specific tab of bootstrap nav tabs on click of a particuler link using jQuery?

HTML:

<a href="PageName.php#tabID">link to other page tab</a>

Javascript:

window.onload = function(){  

    var url = document.location.toString();
    if (url.match('#')) {
        $('.nav-tabs a[href="#' + url.split('#')[1] + '"]').tab('show');
    }

    //Change hash for page-reload
    $('.nav-tabs a[href="#' + url.split('#')[1] + '"]').on('shown', function (e) {
        window.location.hash = e.target.hash;
    }); 
} 

Why is <deny users="?" /> included in the following example?

"At run time, the authorization module iterates through the allow and deny elements, starting at the most local configuration file, until the authorization module finds the first access rule that fits a particular user account. Then, the authorization module grants or denies access to a URL resource depending on whether the first access rule found is an allow or a deny rule. The default authorization rule is . Thus, by default, access is allowed unless configured otherwise."

Article at MSDN

deny = * means deny everyone
deny = ? means deny unauthenticated users

In your 1st example deny * will not affect dan, matthew since they were already allowed by the preceding rule.

According to the docs, here is no difference in your 2 rule sets.

What does \u003C mean?

Those are unicode escapes. The general unicode escapes looks like \uxxxx where xxxx are the hexadecimal digits of the ASCI characters. They are used mainly to insert special characters inside a javascript string.

Laravel Request::all() Should Not Be Called Statically

use the request() helper instead. You don't have to worry about use statements and thus this sort of problem wont happen again.

$input = request()->all();

simple

How to create a session using JavaScript?

You can store and read string information in a cookie.

If it is a session id coming from the server, the server can generate this cookie. And when another request is sent to the server the cookie will come too. Without having to do anything in the browser.

However if it is javascript that creates the session Id. You can create a cookie with javascript, with a function like:

The read function work from any page or tab of the same domain that has written it, either if the cookie was created from the page in javascript or from the server.

Phone number validation Android

You can use android's inbuilt Patterns:

public boolean validCellPhone(String number)
{
    return android.util.Patterns.PHONE.matcher(number).matches();
}

This pattern is intended for searching for things that look like they might be phone numbers in arbitrary text, not for validating whether something is in fact a phone number. It will miss many things that are legitimate phone numbers.

The pattern matches the following:

  • Optionally, a + sign followed immediately by one or more digits. Spaces, dots, or dashes may follow.
  • Optionally, sets of digits in parentheses, separated by spaces, dots, or dashes.
  • A string starting and ending with a digit, containing digits, spaces, dots, and/or dashes.

What is the correct JSON content type?

JSON is a domain-specific language (DSL) and a data format independent of JavaScript, and as such has its own MIME type, application/json. Respect for MIME types is of course client driven, so text/plain may do for transfer of bytes, but then you would be pushing up interpretation to the vendor application domain unnecessarily - application/json. Would you transfer XML via text/plain?

But honestly, your choice of MIME type is advice to the client as to how to interpret the data- text/plain or text/HTML (when it's not HTML) is like type erasure- it's as uninformative as making all your objects of type Object in a typed language.

No browser runtime I know of will take a JSON document and automatically make it available to the runtime as a JavaScript accessible object without intervention, but if you are working with a crippled client, that's an entirely different matter. But that's not the whole story- RESTful JSON services often don't have JavaScript runtimes, but it doesn't stop them using JSON as a viable data interchange format. If clients are that crippled... then I would consider perhaps HTML injection via an Ajax templating service instead.

Application/JSON!

Install a .NET windows service without InstallUtil.exe

You can always fall back to the good old WinAPI calls, although the amount of work involved is non-trivial. There is no requirement that .NET services be installed via a .NET-aware mechanism.

To install:

  • Open the service manager via OpenSCManager.
  • Call CreateService to register the service.
  • Optionally call ChangeServiceConfig2 to set a description.
  • Close the service and service manager handles with CloseServiceHandle.

To uninstall:

  • Open the service manager via OpenSCManager.
  • Open the service using OpenService.
  • Delete the service by calling DeleteService on the handle returned by OpenService.
  • Close the service and service manager handles with CloseServiceHandle.

The main reason I prefer this over using the ServiceInstaller/ServiceProcessInstaller is that you can register the service with your own custom command line arguments. For example, you might register it as "MyApp.exe -service", then if the user runs your app without any arguments you could offer them a UI to install/remove the service.

Running Reflector on ServiceInstaller can fill in the details missing from this brief explanation.

P.S. Clearly this won't have "the same effect as calling: InstallUtil MyService.exe" - in particular, you won't be able to uninstall using InstallUtil. But it seems that perhaps this wasn't an actual stringent requirement for you.

Extract a part of the filepath (a directory) in Python

All you need is parent part if you use pathlib.

from pathlib import Path
p = Path(r'C:\Program Files\Internet Explorer\iexplore.exe')
print(p.parent) 

Will output:

C:\Program Files\Internet Explorer    

Case you need all parts (already covered in other answers) use parts:

p = Path(r'C:\Program Files\Internet Explorer\iexplore.exe')
print(p.parts) 

Then you will get a list:

('C:\\', 'Program Files', 'Internet Explorer', 'iexplore.exe')

Saves tone of time.

Where does Git store files?

It will create your repository in the .git folder in the current directory.

Using comma as list separator with AngularJS

I think it's better to use ng-if. ng-show creates an element in the dom and sets it's display:none. The more dom elements you have the more resource hungry your app becomes, and on devices with lower resources the less dom elements the better.

TBH <span ng-if="!$last">, </span> seems like a great way to do it. It's simple.

How to declare a global variable in C++

In addition to other answers here, if the value is an integral constant, a public enum in a class or struct will work. A variable - constant or otherwise - at the root of a namespace is another option, or a static public member of a class or struct is a third option.

MyClass::eSomeConst (enum)
MyNamespace::nSomeValue 
MyStruct::nSomeValue (static) 

Xcode 4 - build output directory

This was so annoying. Open your project, click on Target, Open Build Phases tab. Check your Copy Bundle Resources for any red items.

Check if a specific tab page is selected (active)

I think that using the event tabPage1.Enter is more convenient.

tabPage1.Enter += new System.EventHandler(tabPage1_Enter);

private void tabPage1_Enter(object sender, EventArgs e)
{
    MessageBox.Show("you entered tabPage1");
}

This is better than having nested if-else statement when you have different logic for different tabs. And more suitable in case new tabs may be added in the future.

Note that this event fires if the form loads and tabPage1 is opened by default.

'AND' vs '&&' as operator

Precedence differs between && and and (&& has higher precedence than and), something that causes confusion when combined with a ternary operator. For instance,

$predA && $predB ? "foo" : "bar"

will return a string whereas

$predA and $predB ? "foo" : "bar"

will return a boolean.

Move UIView up when the keyboard appears in iOS

It can be done easily & automatically if that textfield is in a table's cell (even when the table.scrollable = NO).

NOTE that: the position and size of the table must be reasonable. e.g:

  • if the y position of table is 100 counted from the view's bottom, then the 300 height keyboard will overlap the whole table.
  • if table's height = 10, and the textfield in it must be scrolled up 100 when keyboard appears in order to be visible, then that textfield will be out of the table's bound.

Parsing JSON with Unix tools

On the basis that some of the recommendations here (esp in the comments) suggested the use of Python, I was disappointed not to find an example.

So, here's a one liner to get a single value from some JSON data. It assumes that you are piping the data in (from somewhere) and so should be useful in a scripting context.

echo '{"hostname":"test","domainname":"example.com"}' | python -c 'import json,sys;obj=json.load(sys.stdin);print obj["hostname"]'

Java: Insert multiple rows into MySQL with PreparedStatement

we can be submit multiple updates together in JDBC to submit batch updates.

we can use Statement, PreparedStatement, and CallableStatement objects for bacth update with disable autocommit

addBatch() and executeBatch() functions are available with all statement objects to have BatchUpdate

here addBatch() method adds a set of statements or parameters to the current batch.

MySQL vs MySQLi when using PHP

What is better is PDO; it's a less crufty interface and also provides the same features as MySQLi.

Using prepared statements is good because it eliminates SQL injection possibilities; using server-side prepared statements is bad because it increases the number of round-trips.

MS SQL Date Only Without Time

WHERE DATEDIFF(day, tstamp, @dateParam) = 0

This should get you there if you don't care about time.

This is to answer the meta question of comparing the dates of two values when you don't care about the time.

List the queries running on SQL Server

In the Object Explorer, drill-down to: Server -> Management -> Activity Monitor. This will allow you to see all connections on to the current server.

What is the difference between HTTP 1.1 and HTTP 2.0?

HTTP/2 supports queries multiplexing, headers compression, priority and more intelligent packet streaming management. This results in reduced latency and accelerates content download on modern web pages.

More details here.

Comparing object properties in c#

This method will get properties of the class and compare the values for each property. If any of the values are different, it will return false, else it will return true.

public static bool Compare<T>(T Object1, T object2)
{
    //Get the type of the object
    Type type = typeof(T);

    //return false if any of the object is false
    if (Object1 == null || object2 == null)
        return false;

    //Loop through each properties inside class and get values for the property from both the objects and compare
    foreach (System.Reflection.PropertyInfo property in type.GetProperties())
    {
        if (property.Name != "ExtensionData")
        {
            string Object1Value = string.Empty;
            string Object2Value = string.Empty;
            if (type.GetProperty(property.Name).GetValue(Object1, null) != null)
                Object1Value = type.GetProperty(property.Name).GetValue(Object1, null).ToString();
            if (type.GetProperty(property.Name).GetValue(object2, null) != null)
                Object2Value = type.GetProperty(property.Name).GetValue(object2, null).ToString();
            if (Object1Value.Trim() != Object2Value.Trim())
            {
                return false;
            }
        }
    }
    return true;
}

Usage:

bool isEqual = Compare<Employee>(Object1, Object2)

How do I clear only a few specific objects from the workspace?

A useful way to remove a whole set of named-alike objects:

rm(list = ls()[grep("^tmp", ls())])

thereby removing all objects whose name begins with the string "tmp".

Edit: Following Gsee's comment, making use of the pattern argument:

rm(list = ls(pattern = "^tmp"))

Edit: Answering Rafael comment, one way to retain only a subset of objects is to name the data you want to retain with a specific pattern. For example if you wanted to remove all objects whose name do not start with paper you would issue the following command:

rm(list = grep("^paper", ls(), value = TRUE, invert = TRUE))

Rails create or update magic?

Old question but throwing my solution into the ring for completeness. I needed this when I needed a specific find but a different create if it doesn't exist.

def self.find_by_or_create_with(args, attributes) # READ CAREFULLY! args for finding, attributes for creating!
        obj = self.find_or_initialize_by(args)
        return obj if obj.persisted?
        return obj if obj.update_attributes(attributes) 
end

How can I use LEFT & RIGHT Functions in SQL to get last 3 characters?

You can use RTRIM or cast your value to VARCHAR:

SELECT RIGHT(RTRIM(Field),3), LEFT(Field,LEN(Field)-3)

Or

SELECT RIGHT(CAST(Field AS VARCHAR(15)),3), LEFT(Field,LEN(Field)-3)

CentOS: Copy directory to another directory

As I understand, you want to recursively copy test directory into /home/server/ path...

This can be done as:

-cp -rf /home/server/folder/test/* /home/server/

Hope this helps

How do I remove repeated elements from ArrayList?

If you want to preserve your Order then it is best to use LinkedHashSet. Because if you want to pass this List to an Insert Query by Iterating it, the order would be preserved.

Try this

LinkedHashSet link=new LinkedHashSet();
List listOfValues=new ArrayList();
listOfValues.add(link);

This conversion will be very helpful when you want to return a List but not a Set.

Fatal error: Class 'ZipArchive' not found in

If you are running into this error while using a Docker image and that you are calling the class properly, or that the error comes from an up-to-date library, then the zip module is probably missing.

Assuming we use docker-compose, we can confirm it's missing by running docker-compose run php php -m for instance and see that zip is not listed.

To install it in your image, modify your Dockerfile so it does the same as this example.

FROM php:7.3-apache 

RUN set -eux \
    && apt-get update \
    && apt-get install -y libzip-dev zlib1g-dev \
    && docker-php-ext-install zip

Then rebuild the image with docker-compose build php and you are good to go.

Display only 10 characters of a long string?

Creating own answer, as nobody has considered that the split might not happened (shorter text). In that case we don't want to add '...' as suffix.

Ternary operator will sort that out:

var text = "blahalhahkanhklanlkanhlanlanhak";
var count = 35;

var result = text.slice(0, count) + (text.length > count ? "..." : "");

Can be closed to function:

function fn(text, count){
    return text.slice(0, count) + (text.length > count ? "..." : "");
}

console.log(fn("aognaglkanglnagln", 10));

And expand to helpers class so You can even choose if You want the dots or not:

function fn(text, count, insertDots){
    return text.slice(0, count) + (((text.length > count) && insertDots) ? "..." : "");
}

console.log(fn("aognaglkanglnagln", 10, true));
console.log(fn("aognaglkanglnagln", 10, false));

Remove Server Response Header IIS7

In IIS7 you have to use an HTTP module. Build the following as a class library in VS:

namespace StrongNamespace.HttpModules
{
  public class CustomHeaderModule : IHttpModule
  { 
    public void Init(HttpApplication context)
    {
      context.PreSendRequestHeaders += OnPreSendRequestHeaders;
    } 

    public void Dispose() { } 

    void OnPreSendRequestHeaders(object sender, EventArgs e)
    {
      HttpContext.Current.Response.Headers.Set("Server", "Box of Bolts");
    }
  }
}

Then add the following to your web.config, or you configure it within IIS (if you configure within IIS, the assembly must be in the GAC).

<configuration>
  <system.webServer>
    <modules>
      <add name="CustomHeaderModule"
       type="StrongNamespace.HttpModules.CustomHeaderModule" />
    </modules>
  </system.webServer>
</configuration>

How to show grep result with complete path or file name

The easiest way to print full paths is replace relative start path with absolute path:

grep -r --include="*.sh" "pattern" ${PWD}

CSS3 Fade Effect

You can't transition between two background images, as there's no way for the browser to know what you want to interpolate. As you've discovered, you can transition the background position. If you want the image to fade in on mouse over, I think the best way to do it with CSS transitions is to put the image on a containing element and then animate the background colour to transparent on the link itself:

span {
    background: url(button.png) no-repeat 0 0;
}
a {
    width: 32px;
    height: 32px;
    text-align: left;
    background: rgb(255,255,255);

    -webkit-transition: background 300ms ease-in 200ms; /* property duration timing-function delay */
    -moz-transition: background 300ms ease-in 200ms;
    -o-transition: background 300ms ease-in 200ms;
    transition: background 300ms ease-in 200ms;
    }
a:hover {
    background: rgba(255,255,255,0);
}

On npm install: Unhandled rejection Error: EACCES: permission denied

If none of suggestions in answers worked out, try the following command: npm cache clear --force. It worked for me.

I found it at https://github.com/vuejs/vue-cli/issues/1809.

error: (-215) !empty() in function detectMultiScale

the error may be due to, the required xml files has not been loaded properly. Search for the file haarcascade_frontalface_default.xml by using the search engine of ur OS get the full path and put it as the argument to cv2.CascadeClassifier as string

How to Set Focus on Input Field using JQuery

Justin's answer did not work for me (Chromium 18, Firefox 43.0.1). jQuery's .focus() creates visual highlight, but text cursor does not appear in the field (jquery 3.1.0).

Inspired by https://www.sitepoint.com/jqueryhtml5-input-focus-cursor-positions/ , I added autofocus attribute to the input field and voila!

function addfield() {
    n=$('table tr').length;
    $('table').append('<tr><td><input name=field'+n+' autofocus></td><td><input name=value'+n+'></td></tr>');
    $('input[name="aa"'+n+']').focus();
}

How to remove the default link color of the html hyperlink 'a' tag?

This is also possible:

        a {
            all: unset;
        }

unset: This keyword indicates to change all the properties applying to the element or the element's parent to their parent value if they are inheritable or to their initial value if not. unicode-bidi and direction values are not affected.

Source: Mozilla description of all

How can I slice an ArrayList out of an ArrayList in Java?

I have found a way if you know startIndex and endIndex of the elements one need to remove from ArrayList

Let al be the original ArrayList and startIndex,endIndex be start and end index to be removed from the array respectively:

al.subList(startIndex, endIndex + 1).clear();

How can I detect whether an iframe is loaded?

You can try onload event as well;

var createIframe = function (src) {
        var self = this;
        $('<iframe>', {
            src: src,
            id: 'iframeId',
            frameborder: 1,
            scrolling: 'no',
            onload: function () {
                self.isIframeLoaded = true;
                console.log('loaded!');
            }
        }).appendTo('#iframeContainer');

    };

Could not instantiate mail function. Why this error occurring

Make sure that you also include smtp class which comes with phpmailer:

// for mailing
require("phpmailer/class.phpmailer.php");
require("phpmailer/class.smtp.php");

Use Ant for running program with command line arguments

Can you be a bit more specific about what you're trying to do and how you're trying to do it?

If you're attempting to invoke the program using the <exec> task you might do the following:

<exec executable="name-of-executable">
  <arg value="arg0"/>
  <arg value="arg1"/>
</exec>

Update a column value, replacing part of a string

Try using the REPLACE function:

mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
        -> 'WwWwWw.mysql.com'

Note that it is case sensitive.

Invalid default value for 'dateAdded'

I had the same issue, following fix solved my problem.

  • Select Type as 'TIMESTAMP'

  • DON'T ENTER ANYTHING IN LENGTH/VALUES FIELD. KEEP IT BLANK

  • Select CURRENT_TIMESTAMP as Default value.

I am using MySQL ver 5.5.56

How do I remove time part from JavaScript date?

Split it by space and take first part like below. Hope this will help you.

var d = '12/12/1955 12:00:00 AM';
d = d.split(' ')[0];
console.log(d);

How do I move a file from one location to another in Java?

Try this :-

  boolean success = file.renameTo(new File(Destdir, file.getName()));

Check number of arguments passed to a Bash script

Here a simple one liners to check if only one parameter is given otherwise exit the script:

[ "$#" -ne 1 ] && echo "USAGE $0 <PARAMETER>" && exit

How to use the pass statement?

The pass statement does nothing. It can be used when a statement is required syntactically but the program requires no action.

How to copy file from one location to another location?

  public static void copyFile(File oldLocation, File newLocation) throws IOException {
        if ( oldLocation.exists( )) {
            BufferedInputStream  reader = new BufferedInputStream( new FileInputStream(oldLocation) );
            BufferedOutputStream  writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
            try {
                byte[]  buff = new byte[8192];
                int numChars;
                while ( (numChars = reader.read(  buff, 0, buff.length ) ) != -1) {
                    writer.write( buff, 0, numChars );
                }
            } catch( IOException ex ) {
                throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
            } finally {
                try {
                    if ( reader != null ){                      
                        writer.close();
                        reader.close();
                    }
                } catch( IOException ex ){
                    Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() ); 
                }
            }
        } else {
            throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
        }
    }  

Horizontal swipe slider with jQuery and touch devices support?

Have you seen FlexSlider from WooThemes? I've used it on several recent projects with great success. It's touch enabled too so it will work on both mouse-based browsers as well as touch-based browsers in iOS and Android.

Create random list of integers in Python

Firstly, you should use randrange(0,1000) or randint(0,999), not randint(0,1000). The upper limit of randint is inclusive.

For efficiently, randint is simply a wrapper of randrange which calls random, so you should just use random. Also, use xrange as the argument to sample, not range.

You could use

[a for a in sample(xrange(1000),1000) for _ in range(10000/1000)]

to generate 10,000 numbers in the range using sample 10 times.

(Of course this won't beat NumPy.)

$ python2.7 -m timeit -s 'from random import randrange' '[randrange(1000) for _ in xrange(10000)]'
10 loops, best of 3: 26.1 msec per loop

$ python2.7 -m timeit -s 'from random import sample' '[a%1000 for a in sample(xrange(10000),10000)]'
100 loops, best of 3: 18.4 msec per loop

$ python2.7 -m timeit -s 'from random import random' '[int(1000*random()) for _ in xrange(10000)]' 
100 loops, best of 3: 9.24 msec per loop

$ python2.7 -m timeit -s 'from random import sample' '[a for a in sample(xrange(1000),1000) for _ in range(10000/1000)]'
100 loops, best of 3: 3.79 msec per loop

$ python2.7 -m timeit -s 'from random import shuffle
> def samplefull(x):
>   a = range(x)
>   shuffle(a)
>   return a' '[a for a in samplefull(1000) for _ in xrange(10000/1000)]'
100 loops, best of 3: 3.16 msec per loop

$ python2.7 -m timeit -s 'from numpy.random import randint' 'randint(1000, size=10000)'
1000 loops, best of 3: 363 usec per loop

But since you don't care about the distribution of numbers, why not just use:

range(1000)*(10000/1000)

?

How to read a single character from the user?

This is NON-BLOCKING, reads a key and and stores it in keypress.key.

import Tkinter as tk


class Keypress:
    def __init__(self):
        self.root = tk.Tk()
        self.root.geometry('300x200')
        self.root.bind('<KeyPress>', self.onKeyPress)

    def onKeyPress(self, event):
        self.key = event.char

    def __eq__(self, other):
        return self.key == other

    def __str__(self):
        return self.key

in your programm

keypress = Keypress()

while something:
   do something
   if keypress == 'c':
        break
   elif keypress == 'i': 
       print('info')
   else:
       print("i dont understand %s" % keypress)

Get width/height of SVG element

Use getBBox function

http://jsfiddle.net/Xkv3X/1/

var bBox = svg1.getBBox();
console.log('XxY', bBox.x + 'x' + bBox.y);
console.log('size', bBox.width + 'x' + bBox.height);

There can be only one auto column

My MySQL says "Incorrect table definition; there can be only one auto column and it must be defined as a key" So when I added primary key as below it started working:

CREATE TABLE book (
   id INT AUTO_INCREMENT NOT NULL,
   accepted_terms BIT(1) NOT NULL,
   accepted_privacy BIT(1) NOT NULL,
   primary key (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

SQL Server 2008 - IF NOT EXISTS INSERT ELSE UPDATE

At first glance your original attempt seems pretty close. I'm assuming that clockDate is a DateTime fields so try this:

IF (NOT EXISTS(SELECT * FROM Clock WHERE cast(clockDate as date) = '08/10/2012') 
    AND userName = 'test') 
BEGIN 
    INSERT INTO Clock(clockDate, userName, breakOut) 
    VALUES(GetDate(), 'test', GetDate()) 
END 
ELSE 
BEGIN 
    UPDATE Clock 
    SET breakOut = GetDate()
    WHERE Cast(clockDate AS Date) = '08/10/2012' AND userName = 'test'
END 

Note that getdate gives you the current date. If you are trying to compare to a date (without the time) you need to cast or the time element will cause the compare to fail.


If clockDate is NOT datetime field (just date), then the SQL engine will do it for you - no need to cast on a set/insert statement.

IF (NOT EXISTS(SELECT * FROM Clock WHERE clockDate = '08/10/2012') 
    AND userName = 'test') 
BEGIN 
    INSERT INTO Clock(clockDate, userName, breakOut) 
    VALUES(GetDate(), 'test', GetDate()) 
END 
ELSE 
BEGIN 
    UPDATE Clock 
    SET breakOut = GetDate()
    WHERE clockDate = '08/10/2012' AND userName = 'test'
END 

As others have pointed out, the merge statement is another way to tackle this same logic. However, in some cases, especially with large data sets, the merge statement can be prohibitively slow, causing a lot of tran log activity. So knowing how to logic it out as shown above is still a valid technique.

How to convert a String to CharSequence?

You can use

CharSequence[] cs = String[] {"String to CharSequence"};

Calling a user defined function in jQuery

in my case I did

function myFunc() {
  console.log('myFunc', $(this));
}
$("selector").on("click", "selector", function(e) {
  e.preventDefault();
  myFunc.call(this);
});

properly calls myFunc with the correct this.

Clearing UIWebview cache

After various attempt, only this works well for me (under ios 8):

NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:1 diskCapacity:1 diskPath:nil];
[NSURLCache setSharedURLCache:cache];

Why do people use Heroku when AWS is present? What distinguishes Heroku from AWS?

Sometimes, I wonder why people compare AWS to Heroku. AWS is an IAAS( infrastructure as a service) it clearly speaks how robust and calculative the system is. Heroku, on the other hand, is just a SAAS, it is basically just one fraction of AWS services. So why struggle with setting up AWS when you can ship your first product to the prime using Heroku.

Heroku is free, simple and easy to deploy almost all types of stacks to the web. Heroku is specifically built to bypass all the hassles of shipping your application to a live server in less than no time.

Nevertheless, you may want to deploy your application using any of the tutorials from both parties and compare

AWS DOCS and Heroku Docs

Non-Static method cannot be referenced from a static context with methods and variables

You can either

1) Declare printMenu(), getUserchoice() and input as static

OR

2) If you want to design it better, move the logic from your main into a separate instance method. And then from the main create a new instance of your class and call your instance method(s)

How to hide close button in WPF window?

After much searching for the answer to this, I worked out this simple solution that I will share here in hopes it helps others.

I set WindowStyle=0x10000000.

This sets the WS_VISIBLE (0x10000000) and WS_OVERLAPPED (0x0) values for Window Style. "Overlapped" is the necessary value to show the title bar and window border. By removing the WS_MINIMIZEBOX (0x20000), WS_MAXIMIZEBOX (0x10000), and WS_SYSMENU (0x80000) values from my style value, all the buttons from the title bar were removed, including the Close button.

CMD what does /im (taskkill)?

If you type the executable name and a /? switch at the command line, there is typically help information available. Doing so with taskkill /? provides the following, for instance:

TASKKILL [/S system [/U username [/P [password]]]]
         { [/FI filter] [/PID processid | /IM imagename] } [/T] [/F]

Description:
    This tool is used to terminate tasks by process id (PID) or image name.

Parameter List:
    /S    system           Specifies the remote system to connect to.

    /U    [domain\]user    Specifies the user context under which the
                           command should execute.

    /P    [password]       Specifies the password for the given user
                           context. Prompts for input if omitted.

    /FI   filter           Applies a filter to select a set of tasks.
                           Allows "*" to be used. ex. imagename eq acme*

    /PID  processid        Specifies the PID of the process to be terminated.
                           Use TaskList to get the PID.

    /IM   imagename        Specifies the image name of the process
                           to be terminated. Wildcard '*' can be used
                           to specify all tasks or image names.

    /T                     Terminates the specified process and any
                           child processes which were started by it.

    /F                     Specifies to forcefully terminate the process(es).

    /?                     Displays this help message.

Filters:
    Filter Name   Valid Operators           Valid Value(s)
    -----------   ---------------           -------------------------
    STATUS        eq, ne                    RUNNING |
                                            NOT RESPONDING | UNKNOWN
    IMAGENAME     eq, ne                    Image name
    PID           eq, ne, gt, lt, ge, le    PID value
    SESSION       eq, ne, gt, lt, ge, le    Session number.
    CPUTIME       eq, ne, gt, lt, ge, le    CPU time in the format
                                            of hh:mm:ss.
                                            hh - hours,
                                            mm - minutes, ss - seconds
    MEMUSAGE      eq, ne, gt, lt, ge, le    Memory usage in KB
    USERNAME      eq, ne                    User name in [domain\]user
                                            format
    MODULES       eq, ne                    DLL name
    SERVICES      eq, ne                    Service name
    WINDOWTITLE   eq, ne                    Window title

    NOTE
    ----
    1) Wildcard '*' for /IM switch is accepted only when a filter is applied.
    2) Termination of remote processes will always be done forcefully (/F).
    3) "WINDOWTITLE" and "STATUS" filters are not considered when a remote
       machine is specified.

Examples:
    TASKKILL /IM notepad.exe
    TASKKILL /PID 1230 /PID 1241 /PID 1253 /T
    TASKKILL /F /IM cmd.exe /T 
    TASKKILL /F /FI "PID ge 1000" /FI "WINDOWTITLE ne untitle*"
    TASKKILL /F /FI "USERNAME eq NT AUTHORITY\SYSTEM" /IM notepad.exe
    TASKKILL /S system /U domain\username /FI "USERNAME ne NT*" /IM *
    TASKKILL /S system /U username /P password /FI "IMAGENAME eq note*"

You can also find this information, as well as documentation for most of the other command-line utilities, in the Microsoft TechNet Command-Line Reference

How to detect DIV's dimension changed?

Only Window.onResize exists in the specification, but you can always utilize IFrame to generate new Window object inside your DIV.

Please check this answer. There is a new little jquery plugin, that is portable and easy to use. You can always check the source code to see how it's done.

<!-- (1) include plugin script in a page -->
<script src="/src/jquery-element-onresize.js"></script>

// (2) use the detectResizing plugin to monitor changes to the element's size:
$monitoredElement.detectResizing({ onResize: monitoredElement_onResize });

// (3) write a function to react on changes:
function monitoredElement_onResize() {    
    // logic here...
}

.prop('checked',false) or .removeAttr('checked')?

use checked : true, false property of the checkbox.

jQuery:

if($('input[type=checkbox]').is(':checked')) {
    $(this).prop('checked',true);
} else {
    $(this).prop('checked',false);
}

Crystal Reports - Adding a parameter to a 'Command' query

When you are in the Command, click Create to create a new parameter; call it project_name. Once you've created it, double click its name to add it to the command's text. You query should resemble:

SELECT Projecttname, ReleaseDate, TaskName
FROM DB_Table
WHERE Project_Name LIKE {?project_name} + '*'
AND ReleaseDate >= getdate() --assumes sql server

If desired, link the main report to the subreport on this ({?project_name}) field. If you don't establish a link between the main and subreport, CR will prompt you for the subreport's parameter.

In versions prior to 2008, a command's parameter was only allowed to be a scalar value.

Convert List<String> to List<Integer> directly

Guava Converters do the trick.

import com.google.common.base.Splitter;
import com.google.common.primitives.Longs;

final Iterable<Long> longIds = 
    Longs.stringConverter().convertAll(
        Splitter.on(',').trimResults().omitEmptyStrings()
            .splitToList("1,2,3"));

CROSS JOIN vs INNER JOIN in SQL

The inner join will give the result of matched records between two tables where as the cross join gives you the possible combinations between two tables.

ToList()-- does it create a new list?

From the Reflector'd source:

public static List<TSource> ToList<TSource>(this IEnumerable<TSource> source)
{
    if (source == null)
    {
        throw Error.ArgumentNull("source");
    }
    return new List<TSource>(source);
}

So yes, your original list won't be updated (i.e. additions or removals) however the referenced objects will.

Default value in Doctrine

Adding to @romanb brilliant answer.

This adds a little overhead in migration, because you obviously cannot create a field with not null constraint and with no default value.

// this up() migration is autogenerated, please modify it to your needs
$this->abortIf($this->connection->getDatabasePlatform()->getName() != "postgresql");

//lets add property without not null contraint        
$this->addSql("ALTER TABLE tablename ADD property BOOLEAN");

//get the default value for property       
$object = new Object();
$defaultValue = $menuItem->getProperty() ? "true":"false";

$this->addSql("UPDATE tablename SET property = {$defaultValue}");

//not you can add constraint
$this->addSql("ALTER TABLE tablename ALTER property SET NOT NULL");

With this answer, I encourage you to think why do you need the default value in the database in the first place? And usually it is to allow creating objects with not null constraint.

How to free memory in Java?

Althrough java provides automatic garbage collection sometimes you will want to know how large the object is and how much of it is left .Free memory using programatically import java.lang; and Runtime r=Runtime.getRuntime(); to obtain values of memory using mem1=r.freeMemory(); to free memory call the r.gc(); method and the call freeMemory()

Make 2 functions run at the same time

The answer about threading is good, but you need to be a bit more specific about what you want to do.

If you have two functions that both use a lot of CPU, threading (in CPython) will probably get you nowhere. Then you might want to have a look at the multiprocessing module or possibly you might want to use jython/IronPython.

If CPU-bound performance is the reason, you could even implement things in (non-threaded) C and get a much bigger speedup than doing two parallel things in python.

Without more information, it isn't easy to come up with a good answer.

Correct way to remove plugin from Eclipse

Inspired by sergionni's answer, I ended up doing the following steps:

Help --> Installation Details --> Installation History tab

In the Previous configurations table, you can select a configuration and see in the Configuration contents exactly which plugins were installed and are included in it.

It's easy to find the configuration that contains the plugin you want to remove, using the Compare button. This button is enabled when two configurations are selected.

After tracking the configuration that's responsible for that plugin, select the previous configuration and press the Revert button.

Note that if you revert to a configuration that isn't the one just right before the Current Installation, it causes any other plugins that were installed since, to be uninstalled as well.

What is a callback?

Definition

A callback is executable code that is passed as an argument to other code.

Implementation

// Parent can Read
public class Parent
{
    public string Read(){ /*reads here*/ };
}

// Child need Info
public class Child
{
    private string information;
    // declare a Delegate
    delegate string GetInfo();
    // use an instance of the declared Delegate
    public GetInfo GetMeInformation;

    public void ObtainInfo()
    {
        // Child will use the Parent capabilities via the Delegate
        information = GetMeInformation();
    }
}

Usage

Parent Peter = new Parent();
Child Johny = new Child();

// Tell Johny from where to obtain info
Johny.GetMeInformation = Peter.Read;

Johny.ObtainInfo(); // here Johny 'asks' Peter to read

Links

Create folder with batch but only if it doesn't already exist

if exist C:\VTS\NUL echo "Folder already exists"

if not exist C:\VTS\NUL echo "Folder does not exist"

See also https://support.microsoft.com/en-us/kb/65994

(Update March 7, 2018; Microsoft article is down, archive on https://web.archive.org/web/20150609092521/https://support.microsoft.com/en-us/kb/65994 )

Mercurial undo last commit

One way would be hg rollback (deprecated as of Hg2.7, August 2013)

Please use hg commit --amend instead of rollback to correct mistakes in the last commit.

Roll back the last transaction in a repository.

When committing or merging, Mercurial adds the changeset entry last.
Mercurial keeps a transaction log of the name of each file touched and its length prior to the transaction. On abort, it truncates each file to its prior length. This simplicity is one benefit of making revlogs append-only. The transaction journal also allows an undo operation.

See TortoiseHg Recovery section:

alt text

This thread also details the difference between hg rollback and hg strip:
(written by Martin Geisler who also contributes on SO)

  • 'hg rollback' will remove the last transaction. Transactions are a concept often found in databases. In Mercurial we start a transaction when certain operations are run, such as commit, push, pull...
    When the operation finishes succesfully, the transaction is marked as complete. If an error occurs, the transaction is "rolled back" and the repository is left in the same state as before.
    You can manually trigger a rollback with 'hg rollback'. This will undo the last transactional command. If a pull command brought 10 new changesets into the repository on different branches, then 'hg rollback' will remove them all. Please note: there is no backup when you rollback a transaction!

  • 'hg strip' will remove a changeset and all its descendants. The changesets are saved as a bundle, which you can apply again if you need them back.

ForeverWintr suggests in the comments (in 2016, 5 years later)

You can 'un-commit' files by first hg forgetting them, e.g.: hg forget filea; hg commit --amend, but that seems unintuitive.
hg strip --keep is probably a better solution for modern hg.

Steps to send a https request to a rest service in Node js

Note if you are using https.request do not directly use the body from res.on('data',... This will fail if you have a large data coming in chunks. So you need to concatenate all the data and then process the response in res.on('end'. Example -

  var options = {
    hostname: "www.google.com",
    port: 443,
    path: "/upload",
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Content-Length': Buffer.byteLength(post_data)
    }
  };

  //change to http for local testing
  var req = https.request(options, function (res) {
    res.setEncoding('utf8');

    var body = '';

    res.on('data', function (chunk) {
      body = body + chunk;
    });

    res.on('end',function(){
      console.log("Body :" + body);
      if (res.statusCode != 200) {
        callback("Api call failed with response code " + res.statusCode);
      } else {
        callback(null);
      }
    });

  });

  req.on('error', function (e) {
    console.log("Error : " + e.message);
    callback(e);
  });

  // write data to request body
  req.write(post_data);
  req.end();

Calculating moving average

Or you can simply calculate it using filter, here's the function I use:

ma <- function(x, n = 5){filter(x, rep(1 / n, n), sides = 2)}

If you use dplyr, be careful to specify stats::filter in the function above.

How do I get my Maven Integration tests to run

You should try using maven failsafe plugin. You can tell it to include a certain set of tests.

Completely remove MariaDB or MySQL from CentOS 7 or RHEL 7

systemd

sudo systemctl stop mysqld.service && sudo yum remove -y mariadb mariadb-server && sudo rm -rf /var/lib/mysql /etc/my.cnf

sysvinit

sudo service mysql stop && sudo apt-get remove mariadb mariadb-server && sudo rm -rf /var/lib/mysql /etc/my.cnf

How exactly does <script defer="defer"> work?

Should be also noted that there might be problems in IE<=9 when using script defer in certain situations. More on this: https://github.com/h5bp/lazyweb-requests/issues/42

Error: the entity type requires a primary key

Yet another reason may be that your entity class has several properties named somhow /.*id/i - so ending with ID case insensitive AND elementary type AND there is no [Key] attribute.

EF will namely try to figure out the PK by itself by looking for elementary typed properties ending in ID.

See my case:

public class MyTest, IMustHaveTenant
{
  public long Id { get; set; }
  public int TenantId { get; set; }
  [MaxLength(32)]
  public virtual string Signum{ get; set; }
  public virtual string ID { get; set; }
  public virtual string ID_Other { get; set; }
}

don't ask - lecacy code. The Id was even inherited, so I could not use [Key] (just simplifying the code here)

But here EF is totally confused.

What helped was using modelbuilder this in DBContext class.

            modelBuilder.Entity<MyTest>(f =>
            {
                f.HasKey(e => e.Id);
                f.HasIndex(e => new { e.TenantId });
                f.HasIndex(e => new { e.TenantId, e.ID_Other });
            });

the index on PK is implicit.

535-5.7.8 Username and Password not accepted

Goto config/initializers/setup_mail.rb Check whether the configuration there matches the configuration written in the development.rb file.It should look like the following in both files:

config.action_mailer.smtp_settings = {
     :address =>"[email protected]",
     :port => 587,
     :domain => "gmail.com",
     :user_name => "[email protected]",
     :password => "********",
     :authentication => 'plain',
     :enable_starttls_auto => true,
     :openssl_verify_mode => 'none' 
     } 

This will most certainly solve your problem.

Is there a way to get the XPath in Google Chrome?

You can use $x in the Chrome javascript console. No extensions needed.

ex: $x("//img")

Also the search box in the web inspector will accept xpath