Adding Composer support in your Dotkernel project

TL;DR

Composer is an application-level package manager that auto-loads dependencies (and custom classes) on demand. This article covers the steps needed to add a composer.json file to a Dotkernel project, run composer update, and safely require the generated autoloader so the project works whether or not Composer is present.

First things first

The Dotkernel project must have a composer.json file so that Composer can work. It should look like this:

{
  "require" : {
    "zendframework/zendframework1" : "1.12.*",
    "mobiledetect/mobiledetectlib" : "2.8.*"
  },
  "require-dev" : {
    "php" : ">=5.4.0"
  }
}

Note: zendframework/zendframework1 may not be necessary if you already have ZendServer running or the Zend Framework folder within /usr/share/.

This file makes sure:

• Zend Framework is present and at version > 1.12.*
• MobileDetect is present and at version > 2.8
• The PHP executable is at least at version > 5.4.0 (only for development, because it is not present in the main require)

The dependencies provided in the require section are also loaded for development purposes if not provided in require-dev.

In order to have these components installed, run the following command in your Dotkernel root path:

composer update

If the vendor folder is present, Composer will check for updates and update the packages as needed. If the vendor folder does not exist, Composer will create it, containing all the requested packages, along with an autoload file used to load the dependencies/packages.

Adding Composer Support to Dotkernel

The autoload file created by Composer is used to load the packages:

$composerAutoLoaderPath = realpath(APPLICATION_PATH.'/vendor/autoload.php');
require_once($composerAutoLoaderPath);

But what if the file does not exist, or Composer is not present? First make sure the Composer autoload path exists, and only load the dependencies if the autoload file was found:

$composerAutoLoaderPath = realpath('./vendor/autoload.php');

$composerEnabled = file_exists($composerAutoLoaderPath);

if ($composerEnabled == true) {
    require_once($composerAutoLoaderPath);
} else {
    // handle the error gracefully
    // or load fallbacks - if exist
}

The variable $composerEnabled will be true only if the Composer path exists, so the application behavior can be controlled if Composer is not present.

Later on, the packages can be used like this:

use VendorName\PackageName\ClassName as MyDependency;

$myDependency = new MyDependency($neededArguments);
$myDependency->doSomething();

This article works for any Dotkernel 1.x version if your server is running PHP >5.4.0.

Frequently Asked Questions