What is the function of laravel facade

laravel What is the function of facade

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stay laravel in , The facade Facades For applications IoC The class of the service container provides a static interface ,Laravel As the static proxy of the underlying class in the service container , Compared to traditional static methods , It can provide syntax that is easier to test when maintaining .

The operating environment of this tutorial ：windows10 System 、Laravel6 edition ,DELL G3 The computer .

laravel What's the use of facade

Introduce

Facades For application IoC Service container The class of provides a static interface .Laravel There are some in it Facades, Such as Cache etc. .Laravel As the facade of the underlying class in the service container “ Static proxy ”, Compared to traditional static methods , It can provide easier testing during maintenance 、 More flexible 、 Concise and elegant grammar .

explain

stay Laravel In this context , One Facade It's a class , Using this class, you can access an object from the container , This function is in Facade class .Laravel Of Facades And anything you define Facades, Will inherit Facade This class .

Yours Facade Class only needs to implement one method ：getFacadeAccessor. In a container resolve What come out , It's all done in this way .Facade This base class uses __callStatic() Magic methods , It can be postponed to resolved On the object , come from Facade Call to .

therefore , When you use Facade When called , Like this ：Cache:get,laravel From Ioc Service container Inside resolves Cache management class , Then call the above of this class get Method .Laravel Of Facades You can go to location services , It's a use Laravel Of Ioc Service container More convenient grammar .

advantage

Facade There are many advantages , It provides a simple 、 Easy to remember grammar , Let's use it without remembering the long class name Laravel Features provided , Besides , Because of their concern for PHP Unique usage of dynamic methods , Make them easy to test .

The actual use

The following example , I called Laravel Cache system of . Take a look at the following line of code first , You might think , This is a direct call Cache The one above this class is called get Static method of .

$value = Cache::get('key');

however , If you check Illuminate\Support\Facades\Cache This class , You will find that there is no get This static method ：

class Cache extends Facade {
    /**
     * Get the registered name of the component.
     *
     * @return string
     */
    protected static function getFacadeAccessor() { return 'cache'; }
}

Cache This class inherits Facade The base class , It defines a name getFacadeAccessor() Methods . Be careful , What this method does is to return a Ioc Binding name , Here is the cache.

When the user is quoting anything in Cache This Facade When using static methods on ,Laravel It will start from Ioc Service container Go inside resolves cache This binding , And will execute the requested method on the object （ Here is the get This method ）.

therefore , We're calling Cache::get When , What it really means is this ：

$value = $app->make('cache')->get('key');

Import Facades

Be careful , In the use of facade When , If a namespace is used in the controller , You need to put Facade Class is imported into this namespace . be-all Facades All under the global namespace ：

<?php namespace App\Http\Controllers;
use Cache;
class PhotosController extends Controller {
    /**
     * Get all of the application photos.
     *
     * @return Response
     */
    public function index()
    {
        $photos = Cache::get('photos');
        //
    }
}

establish Facades

establish Facade Only three things are needed ：

• One IoC binding .

• One Facade class .

• One Facade Alias configuration .

Below we define a class ：PaymentGateway\Payment .

namespace PaymentGateway;
class Payment {
    public function process()
    {
        //
    }
}

We need to be able to Ioc Service container Go inside resolve This class . therefore , First, add a Service Provider binding ：

App::bind('payment', function()
{
    return new \PaymentGateway\Payment;
});

The best way to register this binding is to create a new Service Provider , Name it PaymentServiceProvider , Then bind it to register On the way . Then configure laravel stay config/app.php This configuration file loads your Service Provider.

The next step is to create your own Facade class ：

use Illuminate\Support\Facades\Facade;
class Payment extends Facade {
    protected static function getFacadeAccessor() {
             return 'payment'; 
    }
}

Last , If you will , You can go to Facade Add an alias , Put it in config/app.php In the configuration file aliases In the array .

You can call Payment Class process This method . like this ：

Payment::process();

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