Service Provider in Laravel

Overview

If you‘ve ever used Laravel framework in your project, you will hear about server container and service provider. They are the backbone of the Laravel framework and do all heavy jobs when your application runs.

Service container

In Laravel official documentation:

The Laravel service container is a powerful tool for managing class dependencies and performing dependency injection.

Reference : https://laravel.com/docs/5.6/container#introduction

In the simplest way to understand service container, we can assume that it is a box that holds various components’ bindings, and they are served as needed throughout the application.

Service provider

In Laravel official documentation:

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.

Reference : https://laravel.com/docs/5.6/providers#introduction

So whenever you want to inject a service into other services, you can add it into constructor or method, and it’s injected automatically from service container by the service provider.

Let’s have a look at a quick example to understand it.

class MyDemoClass
{
   public function __construct(AwesomeService $awesome_service)
   {
        $awesome_service->doAwesomeThing();
   }
}

As you can see, the MyDemoClass needs an instance of AwesomeService to instantiate itself. So basically, it has a dependency that needs to be injected. Laravel does this automatically by looking into the service container and injecting the appropriate dependency.

It looks great, doesn’t it? There is no charm here, you can look at the contents of file `config/app.php`. You’ll find an array which used to declare all service providers, These service providers will be loaded during the bootstrapping of the Laravel application.

'providers' => [
    /*
    * Laravel Framework Service Providers...
    */
   Illuminate\Auth\AuthServiceProvider::class,
   Illuminate\Broadcasting\BroadcastServiceProvider::class,
   Illuminate\Bus\BusServiceProvider::class,
   Illuminate\Cache\CacheServiceProvider::class,
   Illuminate\Foundation\Providers\ConsoleSupportServiceProvider::class,
   Illuminate\Cookie\CookieServiceProvider::class,
   Illuminate\Database\DatabaseServiceProvider::class,
   Illuminate\Encryption\EncryptionServiceProvider::class,
   Illuminate\Filesystem\FilesystemServiceProvider::class,
   Illuminate\Foundation\Providers\FoundationServiceProvider::class,
   Illuminate\Hashing\HashServiceProvider::class,
   Illuminate\Mail\MailServiceProvider::class,
   Illuminate\Notifications\NotificationServiceProvider::class,
   Illuminate\Pagination\PaginationServiceProvider::class,
   Illuminate\Pipeline\PipelineServiceProvider::class,
   Illuminate\Queue\QueueServiceProvider::class,
   Illuminate\Redis\RedisServiceProvider::class,
   Illuminate\Auth\Passwords\PasswordResetServiceProvider::class,
   Illuminate\Session\SessionServiceProvider::class,
   Illuminate\Translation\TranslationServiceProvider::class,
   Illuminate\Validation\ValidationServiceProvider::class,
   Illuminate\View\ViewServiceProvider::class,
/*
    * Application Service Providers...
    */
   App\Providers\AppServiceProvider::class,
   App\Providers\AuthServiceProvider::class,
   App\Providers\EventServiceProvider::class,
   App\Providers\RouteServiceProvider::class,
/**
    * Custom Provider
    */
],

Create service provider

Create service provider

In Laravel official document, you can create your own service provider by running following cli

php artisan make:provider AwesomeServiceProvider

All service providers extend the Illuminate\Support\ServiceProvider class. Most service providers contain a register and a boot method. 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.

Reference : https://laravel.com/docs/5.6/providers#writing-service-providers

<?php
namespace App\Providers;
use Illuminate\Support\ServiceProvider;
class AwesomeServiceProvider extends ServiceProvider
{
    public function boot()
    {
     //
    }
    public function register()
    {
     //
    }
}

As you see, there are 2 important methods in your class, boot and register.

The register method is the place where you declare all your service container bindings.

On the other hand, the boot method is the place where you can use already registered services via the register method to do awesome things, it means this method is called after all other service providers have been registered.

The register method

There is a very important note from Laravel official document

There is no need to bind classes into the container if they do not depend on any interfaces. The container does not need to be instructed on how to build these objects, since it can automatically resolve these objects using reflection.

Reference : https://laravel.com/docs/5.6/container#binding

So you don’t need to create your own service provider if you don’t have an interface. Laravel will use reflection. That’s what happens in above example with MyDemoClass and AwesomeService.

Now, we go ahead with an example which uses interface, so let create your interface.

<?php
namespace App\Service;
interface AwesomeServiceInterface
{
    public function doAwesomeThing();
}

And the service

<?php
namespace App\Service;
class AwesomeService implements AwesomeServiceInterface
{
    public function doAwesomeThing()
    {
        echo ‘do awesome thing !!!’;
    }
}

After that, instead of binding a class, we’ll bind an interface.

<?php
namespace App\Providers;
use Illuminate\Support\ServiceProvider;
class AwesomeServiceProvider extends ServiceProvider
{
    public function boot()
    {
        //
    }
    
    public function register()
    {
        $this->app->bind(‘App\Service\AwesomeServiceInterface’, ‘App\Service\AwesomeService’);
    }
}

Add your service provider into file config/app.php

‘providers’ => [
    ……
    /**
    * Custom Provider
    */
    App\Providers\AwesomeServiceProvider::class,
],

Let create controller to test your service

<?php
namespace App\Http\Controllers;
use App\Service\AwesomeServiceInterface;
use Illuminate\Http\Request;
use Illuminate\Http\Response;
class TestController extends Controller
{
     public function doAwesome(AwesomeServiceInterface $awesome_service)
     {
         $awesome_service->doAwesomeThing();
         return new Response();
     }
}

This is working follow of above example

Using service provider, it’s flexible to change service injected to others. Behaviors of the consumer are fixed.

And dependency injection decreases coupling between a class and its dependency. So we can implement a class and its dependency at the same time.

For a sample, you inject ProductService which provides function getAllProduct() into ProductController by using the constructor method. You can create MockProductService with hardcoded data to implement ProductController, and the other one can implement ProductService at the same time.

By using the service provider, you can change class injected quickly and easily.

The boot method

If you want to register a view composer within our service provider, this is a perfect place to do that

/**
* Bootstrap services.
*
* @return void
*/
public function boot()
{
    View::composer(
        ‘profile’, ‘App\Http\ViewComposers\ProfileComposer’
    );
}

Conclusion

We just go through the discussion about the service provider, it’s an important part of Laravel framework. And we also have some examples of the service provider.

I hope it’s helpful to you :)