Managing Application Versions

Would it not be nice if we make our application versions, this way we can create new versions of our application while supporting backward compatibility.
By doing this, we would be able to handle multiple versions of our application in a single CodeIgniter installation using the same index file.



There are a couple things we need to setup in order for this to work.

Step 1. Rename Application Folder

Rename your "Application" folder with the first version number you want. You simply rename it with 1.0.0 if its the first version you're creating.

Step 2. Rename index.php

Rename your "index.php" file under the root folder with the new Application folder name which is "1.0.0.php". You would also need to replace the line 117 with the following:

$application_folder = '1.0.0';

Step 3. Create an index.php file

We now have our first application version. We're not done yet, we need to create an index.php file.

<?php
define( 'API_VER', 'v' );
 
array_key_exists( API_VER, $_REQUEST ) ? $v = $_REQUEST[ API_VER ] : $v = '1.0.0';
 
if ( file_exists( "{$v}.php" ) ) {
    if ( is_dir( dirname( __FILE__ ) . "/{$v}" ) ) {
        require dirname( __FILE__ ) . "/{$v}.php";
    } else {
        $error  = new stdClass();
        $error->error        = true;
        $error->description  = 'INVALID_API_VERSION';
        echo json_encode( $error );
        exit;
    }
} else {
    $error  = new stdClass();
    $error->error        = true;
    $error->description  = 'INVALID_API_VERSION';
    echo json_encode( $error );
    exit;
}

What our index file does is it takes the value of "v" variable then checks the file with the version name if it exists. If it does exists, it loads the corresponding application version, otherwise, it throws an error message. If no version is passed, it simply loads the 1.0.0 version.
To add more application folder, simply duplicate 1.0.0 folder and 1.0.0.php file then rename it with the version number you want. You can now access your application versions by simply adding your version number after your base url.
Ex. "localhost/ci_proj/?v=1.0.0"
I hope you've found this tip useful.
Learn more advanced codeigniter techniques.