{"id":1863,"date":"2021-05-26T07:48:01","date_gmt":"2021-05-26T07:48:01","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=1863"},"modified":"2021-06-27T05:07:41","modified_gmt":"2021-06-27T05:07:41","slug":"php-composer-autoload","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-oop\/php-composer-autoload\/","title":{"rendered":"PHP Composer Autoload"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use Composer to autoload PHP classes from files using PSR-4 standard.<\/p>\n\n\n\n

Loading classes using the require_once construct #<\/a><\/h2>\n\n\n\n

First, create the following directory structure with files:<\/p>\n\n\n

.\n\u251c\u2500\u2500 app\n\u2502   \u251c\u2500\u2500 bootstrap.php\n\u2502   \u2514\u2500\u2500 models\n\u2502       \u2514\u2500\u2500 User.php\n\u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
<?php<\/span>\n\nclass<\/span> User<\/span>\n<\/span>{\n    private<\/span> $username;\n\n    private<\/span> $password;\n\n    public<\/span> function<\/span> __construct<\/span>($username, $password)<\/span>\n    <\/span>{\n        $this<\/span>->username = $username;\n        $this<\/span>->password = password_hash($password);\n    }\n\n    public<\/span> function<\/span> getUsername<\/span>()<\/span>: string<\/span>\n    <\/span>{\n        return<\/span> $this<\/span>->username;\n    }\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The bootstrap.php<\/code> file uses the require_once<\/a><\/code> construct to load the User<\/code> class from the User.php<\/code> file in the models<\/code> folder:<\/p>\n\n\n
<?php<\/span>\n\nrequire_once<\/span> 'models\/User.php'<\/span>;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
When you have more classes in the models<\/code> folder, you can add more require_once<\/code> statement to the bootstrap.php<\/code> file to load those classes.<\/p>\n\n\n\n
The index.php<\/code> file loads the bootstrap.php<\/code> file and uses the User<\/code> class:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> '.\/app\/bootstrap.php'<\/span>;\n\n$user = new<\/span> User('admin'<\/span>, '$ecurePa$$w0rd1'<\/span>);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The problem with the spl_autoload_register()<\/code> function is that you have to implement the autoloader functions by yourself. And your autoloaders may not like autoloaders developed by other developers.<\/p>\n\n\n\n
Therefore, when you work with a different codebase, you need to study the autoloaders in that particular codebase to understand how they work.<\/p>\n\n\n\n
This is why Composer comes into play.<\/p>\n\n\n\n
Introduction to the Composer #<\/a><\/h2>\n\n\n\n
Composer <\/a>is a dependency manager for PHP. Composer allows you to manage dependencies in your PHP project. In this tutorial, we’ll focus on how to use the Composer for autoloading classes.<\/p>\n\n\n\n
Before using Composer, you need to download and install it. The official documentation provides you with the detailed steps of how to download and install Composer on your computer<\/a>. <\/p>\n\n\n\n
To check whether the Composer installed successfully, you run the following command from the Command Prompt on Windows or Terminal on macOS and Linux:<\/p>\n\n\n
composer -v<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
It’ll return the current version and a lot of options that you can use with the composer<\/code> command.<\/p>\n\n\n\n
Autoloading classes with Composer #<\/a><\/h2>\n\n\n\n
Back the the previous example, to use the Composer, you first create a new file called composer.json<\/code> under the project’s root folder. The project directory will look like this:<\/p>\n\n\n
.\n\u251c\u2500\u2500 app\n\u2502   \u251c\u2500\u2500 bootstrap.php\n\u2502   \u2514\u2500\u2500 models\n\u2502       \u2514\u2500\u2500 User.php\n\u251c\u2500\u2500 composer.json\n\u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In the composer.json<\/code>, you add the following code:<\/p>\n\n\n
{\n    \"autoload\"<\/span>: {\n        \"classmap\"<\/span>: [\"app\/models\"<\/span>]\n    }\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
This code means that Composer will autoload all class files defined the app\/models<\/code> folder.<\/p>\n\n\n\n
If you have classes from other folders that you want to load, you can specify them in classmap<\/code> array:<\/p>\n\n\n
    {\n        \"autoload\"<\/span>: {\n            \"classmap\"<\/span>: [\"app\/models\"<\/span>, \"app\/services\"<\/span>]\n        }\n    }<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, Composer will load classes from both models<\/code> and services<\/code> folders under the app<\/code> folder.<\/p>\n\n\n\n
Next, launch the Command Prompt on Windows or Terminal on macOS and Linux, and navigate to the project directory.<\/p>\n\n\n\n
Then, type the following command from the project directory:<\/p>\n\n\n
composer dump-autoload<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Composer will generate a directory called vendor<\/code> that contains a number of files like this:<\/p>\n\n\n
.\n\u251c\u2500\u2500 app\n\u2502   \u251c\u2500\u2500 bootstrap.php\n\u2502   \u2514\u2500\u2500 models\n\u2502       \u2514\u2500\u2500 User.php\n\u251c\u2500\u2500 composer.json\n\u251c\u2500\u2500 index.php\n\u2514\u2500\u2500 vendor\n    \u251c\u2500\u2500 autoload.php\n    \u2514\u2500\u2500 composer\n        \u251c\u2500\u2500 autoload_classmap.php\n        \u251c\u2500\u2500 autoload_namespaces.php\n        \u251c\u2500\u2500 autoload_psr4.php\n        \u251c\u2500\u2500 autoload_real.php\n        \u251c\u2500\u2500 autoload_static.php\n        \u251c\u2500\u2500 ClassLoader.php\n        \u2514\u2500\u2500 LICENSE<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The most important file to you for now is autoload.php<\/code> file.<\/p>\n\n\n\n
After that, load the autoload.php<\/code> file in the bootstrap.php<\/code> file using the require_once<\/code> construct:<\/p>\n\n\n
<?php<\/span>\n\nrequire_once<\/span> __DIR__<\/span> . '\/..\/vendor\/autoload.php'<\/span>;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Finally, you can use the User<\/code> class in the index.php<\/code>:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> '.\/app\/bootstrap.php'<\/span>;\n\n$user = new<\/span> User('admin'<\/span>, '$ecurePa$$w0rd1'<\/span>);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
From now, whenever you have a new class in the models<\/code> directory, you need to run the command composer dump-autoload<\/code> again to regenerate the autoload.php<\/code> file.<\/p>\n\n\n\n
For example, the following defines a new class called Comment<\/code> in the Comment.php<\/code> file under the models<\/code> folder:<\/p>\n\n\n
<?php<\/span>\n\nclass<\/span> Comment<\/span>\n<\/span>{\n    private<\/span> $comment;\n\n    public<\/span> function<\/span> __construct<\/span>(string $comment)<\/span>\n    <\/span>{\n        $this<\/span>->comment = $comment;\n    }\n\n    public<\/span> function<\/span> getComment<\/span>()<\/span>: string<\/span>\n    <\/span>{\n        return<\/span> strip_tags($this<\/span>->comment);\n    }\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
If you don’t run the composer dump-autoload<\/code> command and use the Comment<\/code> class in the index.php<\/code> file, you’ll get an error:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> '.\/app\/bootstrap.php'<\/span>;\n\n$user = new<\/span> User('admin'<\/span>, '$ecurePa$$w0rd1'<\/span>);\n\n$comment = new<\/span> Comment('<h1>Hello<\/h1>'<\/span>);\necho<\/span> $comment->getComment();<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Error:<\/p>\n\n\n
Fatal error: Uncaught Error: Class<\/span> 'Comment<\/span>' not<\/span> found<\/span> in<\/span>...<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
However, if you run the composer dump-autoload<\/code> command again, the index.php<\/code> file will work properly.<\/p>\n\n\n\n
Composer autoload with PSR-4 #<\/a><\/h2>\n\n\n\n
PSR stands for PHP Standard Recommendation. PSR is a PHP specification published by the PHP Framework Interop Group or PHP-FIG.<\/p>\n\n\n\n
The goals of PSR are to enable interoperability of PHP components and to provide a common technical basis for the implementation of best practices in PHP programming.<\/p>\n\n\n\n
PHP-FIG has published a lot of PSR starting from PSR-0. For a complete list of PSR, check it out the PSR page<\/a>.<\/p>\n\n\n\n
PSR-4 is auto-loading standard<\/a> that describes the specification for autoloading classes from file paths. https:\/\/www.php-fig.org\/psr\/psr-4\/<\/p>\n\n\n\n
According to the PSR-4, a fully qualified class name has the following structure:<\/p>\n\n\n
 \\<NamespaceName>(\\<SubNamespaceNames>)*\\<ClassName><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The structure starts with a namespace, followed by one or more sub namespaces, and the class name.<\/p>\n\n\n\n
To comply with PSR-4, you need to structure the previous application like this:<\/p>\n\n\n
.\n\u251c\u2500\u2500 app\n\u2502   \u251c\u2500\u2500 Acme\n\u2502   \u2502   \u251c\u2500\u2500 Auth\n\u2502   \u2502   \u2502   \u2514\u2500\u2500 User.php\n\u2502   \u2502   \u2514\u2500\u2500 Blog\n\u2502   \u2502       \u2514\u2500\u2500 Comment.php\n\u2502   \u2514\u2500\u2500 bootstrap.php\n\u251c\u2500\u2500 composer.json\n\u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The new structure has the following changes:<\/p>\n\n\n\n
First, the models<\/code> directory is deleted.<\/p>\n\n\n\n
Second, the User.php<\/code> is under the Acme\/Auth<\/code> folder. And the User<\/code> class is namespaced with Acme\/Auth<\/code>. Notice how namespaces map to the directory structure. This also helps you find a class file more quickly by looking at its namespace.<\/p>\n\n\n
<?php<\/span>\n\nnamespace<\/span> Acme<\/span>\\Auth<\/span>;\n\nclass<\/span> User<\/span>\n<\/span>{\n    \/\/ implementation<\/span>\n    \/\/ ...<\/span>\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, the Comment.php<\/code> is under the Acme\/Blog<\/code> folder. The Comment<\/code> class has the namespace Acme\\Blog<\/code>:<\/p>\n\n\n
<?php<\/span>\n\nnamespace<\/span> Acme<\/span>\\Blog<\/span>;\n\nclass<\/span> Comment<\/span>\n<\/span>{\n    \/\/ implementation<\/span>\n    \/\/ ...<\/span>\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Fourth, the composer.json<\/code> file looks like the following:<\/p>\n\n\n
{\n    \"autoload\"<\/span>: {\n        \"psr-4\"<\/span>: {\n            \"Acme\\\\\"<\/span>:\"app\/Acme\"<\/span>\n        }\n    }\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Instead using the classmap<\/code>, the composer.json<\/code> file now uses psr-4<\/code>. The psr-4<\/code> maps the namespace \"Acme\\\\\"<\/code> to the \"app\/Acme\"<\/code> folder.<\/p>\n\n\n\n
Note that the second backslash (\\<\/code>) in the Acme\\<\/code> namespace is used to escape the first backslash (\\<\/code>).<\/p>\n\n\n\n
Fifth, to use the User<\/code> and Comment<\/code> classes in the index.php<\/code> file, you need to run the composer dump-autoload<\/code> command to generate the autoload.php file:<\/p>\n\n\n
composer dump-autoload<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Since the User<\/code> and Comment<\/code> classes have namespaces, you need to have the use<\/code> statements in index.php<\/code> as follows:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> '.\/app\/bootstrap.php'<\/span>;\n\nuse<\/span> Acme<\/span>\\Auth<\/span>\\User<\/span> as<\/span> User<\/span>;\nuse<\/span> Acme<\/span>\\Blog<\/span>\\Comment<\/span> as<\/span> Comment<\/span>;\n\n$user = new<\/span> User('admin'<\/span>, '$ecurePa$$w0rd1'<\/span>);\n\n$comment = new<\/span> Comment('<h1>Hello<\/h1>'<\/span>);\necho<\/span> $comment->getComment();<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • Composer is a dependency management tool in PHP.<\/li>
  • Use PSR-4 for organizing directory and class files.<\/li>
  • Use the composer dump-autoload<\/code> command to generate the autoload.php<\/code> file.<\/li><\/ul>\n
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    Did you find this tutorial useful?<\/div>\n\t\t
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This application structure works well if you have a small number of classes. However, when the application has a large number of classes, the require_once<\/code> doesn’t scale well. In this case, you can use the spl_autoload_register()<\/a><\/code> function to automatically loads the classes from their files<\/a>.<\/p>\n\n\n\n
The User<\/code> is a simple class. It has two properties $username<\/code> and $password<\/code>. The constructor<\/a> initializes the properties from its arguments. Also, it uses the password_hash()<\/code> function to hash the $password<\/code>.<\/p>\n\n\n\n
The User.php<\/code> file in the models<\/code> folder holds the User<\/code> class<\/a>:<\/p>\n\n\n