Tag Archives: Computing

Detecting Pressed Key with e.which in JavaScript

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You have definitely decided to get which key has been pressed with JavaScript? This is very common when it comes to an Enter key press over a form element. Actually this should be automatically done by the browser, but when it comes to a default prevented form you’ve to check it for yourself.

The job can be done with a event’s which check. Let me show you some JavaScript/jQuery code:

$('.selector').click(function(e) {
	console.log(e.which);	
});

Note that this can be checked under Firefox and/or Safari like browsers which support the console object. This will give you the idea which key is pressed in a number value. The Enter is usually 13!
If you don’t have such browser, you can replace that code with something like:

$('.selector').click(function(e) {
	alert(e.which);	
});

PHP: Conditionals Coding Style

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Just to continue with PHP coding style, let me suggest a conditional statement coding standard. Just don’t use large three operands conditions like that:

condition ? if_true : if_false

If it’s too long it will be difficult to read and maintain. Better is:

(condition)
	? (if_true)
	: (if_false);

Download Files with Zend Framework

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Download a File

The title may sound unclear enough, but the task is simple. You’ve to make a file download process within a Zend Framework’s controller. Let’s assume we’ve the DownloadController setup:

<?php
 
class DownloadController extends Zend_Controller_Action
{
	public function indexAction()
	{}	
}

In PHP there are at least three simple lines of code that will do the job of downloading a file.

header('Content-Type: image/jpeg');
header('Content-Disposition: attachment; filename="logo.jpg"');
readfile('images/logo.jpg');

Note that here there is a content-type header, which is important cause the browsers understands what kind of file is supposed to be downloaded. The second line suggests a name of the downloaded file and the third one returns the file to the client.

Download a File … within Zend Framework

Those three lines wont work alone in a ZF application, because there’s no view, but even if you create a .phtml (view) file for this action it won’t work, because the header of the returned file is modified.

The question is how to possibly return the file for download, perhaps write some statistics to the database and if there’s a problem (some permission issues for instance) return a message to the user.

The Basic Solution

The solution is simple. First make it work by disabling the view and possibly the layout for this action:

public function indexAction()
{
	header('Content-Type: image/jpeg');
	header('Content-Disposition: attachment; filename="logo.jpg"');
	readfile('images/logo.jpg');
 
	// disable the view ... and perhaps the layout
	$this->view->layout()->disableLayout();
        $this->_helper->viewRenderer->setNoRender(true);
}

Than add some code where you can check the permissions. Just because there’s no view for this action you can redirect to another – errorAction():

public function indexAction()
{
    if (userHasNoPermissions) {
        $this->view->msg = 'This file cannot be downloaded!';
        $this->_forward('error', 'download');
    }
 
    header('Content-Type: image/jpeg');
    header('Content-Disposition: attachment; filename="logo.jpg"');
    readfile('images/logo.jpg');
 
    // disable layout and view
    $this->view->layout()->disableLayout();
    $this->_helper->viewRenderer->setNoRender(true);
}

But that still will prompt you a file to download, so there should be a return statement that will return false:

public function indexAction()
{
    if (userHasNoPermissions) {
        $this->view->msg = 'This file cannot be downloaded!';
        $this->_forward('error', 'download');
        return FALSE;
    }
 
    header('Content-Type: image/jpeg');
    header('Content-Disposition: attachment; filename="logo.jpg"');
    readfile('images/logo.jpg');
 
    // disable layout and view
    $this->view->layout()->disableLayout();
    $this->_helper->viewRenderer->setNoRender(true);
}

So here’s the complete source of DownloadController.php:

<?php
 
class DownloadController extends Zend_Controller_Action
{
	public function indexAction()
	{
	    if (userHasNoPermissions) {
	        $this->view->msg = 'This file cannot be downloaded!';
	        $this->_forward('error', 'download');
	        return FALSE;
	    }
 
	    header('Content-Type: image/jpeg');
	    header('Content-Disposition: attachment; filename="logo.jpg"');
	    readfile('images/logo.jpg');
 
	    // disable layout and view
	    $this->view->layout()->disableLayout();
	    $this->_helper->viewRenderer->setNoRender(true);
	}	
 
	public function errorAction()
	{}
}

and the error.phtml:

<?php echo $this->msg ?>

PHP Coding Style: Large IF Statements

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Have you ever seen some PHP code like that:

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if ($condition1 && $condition2 && $string1 == $string2 . $string3 && $string4 != $string5 . $string6) {
   // write some code here!?
}

It is ugly, isn’t it?

I’d prefer to make it clearer! What about that?

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if ($condition1 
   && $condition2
   && $string1 == $string2
                . $string3
   && $string4 != $string5
                . $string6
) {
   // write some code here
}

JavaScript Objects Coding Style

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JavaScript vs. PHP

Continuing from my post about PHP arrays coding style and following the comments of that post, I’d like to write a bit about JavaScript objects’ coding style.

You perhaps know that the term object is quite undefined or under estimated in the JavaScript world, but I’d speak about the key/value pairs in JS commonly formatted like that:

var obj = { key : 'value' }

Here you can add more and more key/value pairs, but what’s different from the PHP associative arrays and what’s the same and should be cosidered.

The Same as PHP?

I wrote about the alignment in PHP and hashes. Than I showed how I align them:

$arr = array(
   'short'   => 'val',
   'longkey' => 'val'
);

In JavaScript you should use the same technique of alignment:

var obj = {
   'short'   : 'val',
   'longkey' : 'val'
};

Some Differences

Yes, there are more differences, which is normal. First of all you don’t have the => notation in JavaScript and a : is used. Second and most important you cannot add a trailing comma after the last key/value pair. Note that in PHP that’s fine!

// that will throw an error in MSIE
var obj = {
   'short'   : 'val',
   'longkey' : 'val',
};

while this is OK in PHP and it’s encouraged:

$arr = array(
   'short'   => 'val',
   'longkey' => 'val',
);