Prevent HTTP Cache with PHP

HTTP Cache

HTTP Cache can be troublesome during development in some occasions specially in developing and testing web services, testing endpoints. We can use PHP headers to prevent and disable HTTP cache. 

header("Content-Type: application/json");
header("Expires: 0");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

 Other than the above, there are other techniques of prevent  browser caching.

CodeIgniter Like Flash Data in PHP

CodeIgniter

class FlashMessage {

    public static function render() {
        if (!isset($_SESSION['my_my_messages'])) {
            return null;
        }
        $my_messages = $_SESSION['my_messages'];
        unset($_SESSION['my_messages']);
        return implode('<br/>', $my_messages);
    }

    public static function add($message) {
        if (!isset($_SESSION['my_messages'])) {
            $_SESSION['my_messages'] = array();
        }
        $_SESSION['my_messages'][] = $message;
    }

}

iPhone Push Notifications PHP Server

<?php
$ctx = stream_context_create();
stream_context_set_option($ctx, 'ssl', 'local_cert', YOUR_.PEM_FILE);
stream_context_set_option($ctx, 'ssl', 'passphrase', YOUR_PASSPHRASE);
 
$fp = stream_socket_client(
        'ssl://gateway.sandbox.push.apple.com:2195', $err, $errstr, 60, STREAM_CLIENT_CONNECT | STREAM_CLIENT_PERSISTENT, $ctx);
 
if (!$fp) {
    exit("Failed to connect: $err $errstr

");
}
 
echo 'Connected to APN
';
 
 
// Create the payload body
$body['aps'] = array(
    'badge' => +1,
    'alert' => 'Testing push notifications',
    'sound' => 'new_wall_paper.wav',
    'action-loc-key' => 'OK'
);
 
$payload = json_encode($body);
 
for ($i = 0; $i < count($tokens); $i++) {
    $msg = chr(0) . pack('n', 32) . pack('H*', $tokens [$i]) . pack('n', strlen($payload)) . $payload;
    fwrite($fp, $msg, strlen($msg));
}
 
echo "Completed sending messages";
fclose($fp);
?>

Passing Multiple Parameters to Form Validation Custom Callbacks in Codeigniter

CI natively only allows for  single parameter in custom callbacks. For an instance see the following code.

$this->form_validation->set_rules
('hstate', 'State', 'required|callback_suburb_check[' . $suburb . ']');

If you need to pass multiple parameters, you have several options. Obviously you can change CI behaviour by subclassing the core library. But in this tutorial we follow the less pain approach. That 's to access required parameters via POST variables within your custom callback function. They are still available in this scope.

There is another way using your PHP string handling knowledge. Just formatting all the parameters as single string and passing to the callback function.

$parameters = 'first_arg' . '||' . 'second_arg' . '||' . 'third_arg';
$this->form_validation->set_rules
('some_field', 'Some Field Name', 'callback__my_callback_function['.$parameters.']');

Then in your callback,

function _my_callback_function($field_value, $second_parameter){
    list($first_param, $second_param, $third_param) = split('||', $second_parameter);
    ...
}

How to check HTML5 Web Storage Support in JavaScript?

HTML5 Data Storage

function supports_html5_storage() {
                try {
                    return 'sessionStorage' in window && window['sessionStorage'] !== null;
                } catch (e) {
                    return false;
                }
            }
            alert(supports_html5_storage());

How to remove index.php from CodeIgniter URL in Ubuntu

CodeIgniter

In application/config/config.php
change:

$config['index_page']='index.php';

to

$config['index_page']='';

Create or modify .htaccess in project root with following content.

# Customized error messages.
ErrorDocument 404 /index.php
# Set the default handler.
DirectoryIndex index.php
# Various rewrite rules.

  RewriteEngine on
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php?/$1 [L,QSA]

Also allow overriding .htaccess in your apache

/etc/apache2/sites-available/default

and edit the file & change to

AllowOverrideAll

and Restart Apache

sudo /etc/init.d/apache2 reload

or

sudo service apache2 reload

or

sudo /etc/init.d/httpd reload