Laravel service container (Application of context binding)

Context binding , According to different strategies, dependency injection is agreed service .

The example on the official website shows that , Different file types , Different storage schemes are used .

use App\Http\Controllers\PhotoController;
use App\Http\Controllers\UploadController;
use App\Http\Controllers\VideoController;
use Illuminate\Contracts\Filesystem\Filesystem;
use Illuminate\Support\Facades\Storage;

$this->app->when(PhotoController::class)
          ->needs(Filesystem::class)
          ->give(function () {
    
              return Storage::disk('local');
          });

$this->app->when([VideoController::class, UploadController::class])
          ->needs(Filesystem::class)
          ->give(function () {
    
              return Storage::disk('s3');
          });

It's easy to understand , What other scenarios can this be used in , How to use it ？ Here's an example .

Example

For example, I want to deliver a batch of e-commerce products , To ship Fruits , And nuts . The timeliness of fruits is relatively strong , Therefore, it is recommended to deliver Shunfeng . If the shelf life of nuts is long, it's ok , I choose a Zhongtong .

Code implementation

Create an interface ：

<?php
namespace App\Contracts;
interface Express
{
    
    /** *  Access to third parties   The price of logistics configuration  * @return mixed */
    public function getAmount();
}

At present, I only need to get the express price .

Create SF ：

<?php
namespace App\Services\express;
use App\Contracts\Express;

class Shunfeng implements Express
{
    
    public function getAmount()
    {
    
        return 20;
    }
}

Tact

<?php


namespace App\Services\express;
use App\Contracts\Express;
class Yuantong implements Express
{
    
    public function getAmount()
    {
    
        return 10;
    }
}

stay Providers/AppServiceProvider.php Of register Method to add binding information

 $this->app->when('App\Http\Controllers\Fruit')
     ->needs(Express::class)
     ->give(Shunfeng::class);

 $this->app->when('App\Http\Controllers\Nut')
     ->needs(Express::class)
     ->give(Yuantong::class);

You can see from the registration information above , If the controller of the fruit is called , At the same time, the interface is Express When , Inject the instance of SF . If the controller of the nut is called , At the same time, the interface is Express When , An example of injecting circularity .

controller ：

<?php
namespace App\Http\Controllers;
class Fruit
{
    
    public $express;
    public function __construct(\App\Contracts\Express $express)
    {
    
        $this->express = $express;
    }
    public function get()
    {
    
        return $this->express->getAmount();
    }
}

Here is an example of a fruit , When routing to Fruit When the controller , It will inject the instance of SF just defined .

stay routers/web.php Add routing information

Route::get('fruit',[\App\Http\Controllers\Fruit::class,'get']);

Route::get('nut',[\App\Http\Controllers\Nut::class,'get']);

request /fruit The data obtained is ：

request /nut The data obtained is ：

git Source code