Service Providers

• Introduction
• Writing Service Providers
  • The Register Method
  • The Boot Method
• Registering Providers
• Deferred Providers

Introduction

Service providers are the central place of all Laravel application bootstrapping. Your own application, as well as all of Laravel's core services are bootstrapped via service providers.

But, what do we mean by "bootstrapped"? In general, we mean registering things, including registering service container bindings, event listeners, middleware, and even routes. Service providers are the central place to configure your application.

If you open the config/app.php file included with Laravel, you will see a providers array. These are all of the service provider classes that will be loaded for your application. Of course, many of them are "deferred" providers, meaning they will not be loaded on every request, but only when the services they provide are actually needed.

In this overview you will learn how to write your own service providers and register them with your Laravel application.

Writing Service Providers

All service providers extend the Illuminate\Support\ServiceProvider class. This abstract class requires that you define at least one method on your provider: register. Within the register method, you should only bind things into the service container. You should never attempt to register any event listeners, routes, or any other piece of functionality within the register method.

The Artisan CLI can easily generate a new provider via the make:provider command:

php artisan make:provider RiakServiceProvider

The Register Method

As mentioned previously, within the register method, you should only bind things into the service container. You should never attempt to register any event listeners, routes, or any other piece of functionality within the register method. Otherwise, you may accidently use a service that is provided by a service provider which has not loaded yet.

Now, let's take a look at a basic service provider:

<?php
namespace App\Providers;
use Riak\Connection;
use Illuminate\Support\ServiceProvider;
class RiakServiceProvider extends ServiceProvider
{
    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function register()
    {
        $this->app->singleton(Connection::class, function ($app) {
            return new Connection(config('riak'));
        });
    }
}

This service provider only defines a register method, and uses that method to define an implementation of Riak\Connection in the service container. If you don't understand how the service container works, check out its documentation.

The Boot Method

So, what if we need to register a view composer within our service provider? This should be done within the boot method. This method is called after all other service providers have been registered, meaning you have access to all other services that have been registered by the framework:

<?php
namespace App\Providers;
use Illuminate\Contracts\Events\Dispatcher as DispatcherContract;
use Illuminate\Foundation\Support\Providers\EventServiceProvider as ServiceProvider;
class EventServiceProvider extends ServiceProvider
{
    // Other Service Provider Properties...
    /**
     * Register any other events for your application.
     *
     * @param  \Illuminate\Contracts\Events\Dispatcher  $events
     * @return void
     */
    public function boot(DispatcherContract $events)
    {
        parent::boot($events);
        view()->composer('view', function () {
            //
        });
    }
}

Boot Method Dependency Injection

You are able to type-hint dependencies for your service provider's boot method. The service container will automatically inject any dependencies you need:

use Illuminate\Contracts\Routing\ResponseFactory;
public function boot(ResponseFactory $factory)
{
    $factory->macro('caps', function ($value) {
        //
    });
}

Registering Providers

All service providers are registered in the config/app.php configuration file. This file contains a providers array where you can list the names of your service providers. By default, a set of Laravel core service providers are listed in this array. These providers bootstrap the core Laravel components, such as the mailer, queue, cache, and others.

To register your provider, simply add it to the array:

'providers' => [
    // Other Service Providers
    App\Providers\AppServiceProvider::class,
],

Deferred Providers

If your provider is only registering bindings in the service container, you may choose to defer its registration until one of the registered bindings is actually needed. Deferring the loading of such a provider will improve the performance of your application, since it is not loaded from the filesystem on every request.

To defer the loading of a provider, set the defer property to true and define a provides method. The provides method returns the service container bindings that the provider registers:

<?php
namespace App\Providers;
use Riak\Connection;
use Illuminate\Support\ServiceProvider;
class RiakServiceProvider extends ServiceProvider
{
    /**
     * Indicates if loading of the provider is deferred.
     *
     * @var bool
     */
    protected $defer = true;
    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        $this->app->singleton(Connection::class, function ($app) {
            return new Connection($app['config']['riak']);
        });
    }
    /**
     * Get the services provided by the provider.
     *
     * @return array
     */
    public function provides()
    {
        return [Connection::class];
    }
}

Laravel compiles and stores a list of all of the services supplied by deferred service providers, along with the name of its service provider class. Then, only when you attempt to resolve one of these services does Laravel load the service provider.