php 无法解析的依赖解析 [Parameter #0 [ <required> $name ]]

Unresolvable dependency resolving [Parameter #0 [ <required> $name ]]

提问by Martin

Warning:This question is Laravel 4 specific.

警告：这个问题是 Laravel 4 特有的。

I've been using Facades in my controllers before. Therefore I know the code is working. Now I need to introduce dependency injection for various reasons.

我之前一直在我的控制器中使用 Facades。因此我知道代码正在运行。现在由于各种原因需要引入依赖注入。

After refactoring the controller I get following error:

重构控制器后，我收到以下错误：

Illuminate \ Container \ BindingResolutionException

Unresolvable dependency resolving [Parameter #0 [ $name ]].

照亮 \ 容器 \ BindingResolutionException

无法解析的依赖解析 [Parameter #0 [ $name ]]。

I can't figure out where the problem is. The Error message seems cryptic to me and I don't understand it. (I don't see any problem with my __constructorparameters since I've registered the binding for the HelpersInterface)

我无法弄清楚问题出在哪里。错误消息对我来说似乎很神秘，我不明白。（我没有看到我的__constructor参数有任何问题，因为我已经为 注册了绑定HelpersInterface）

Here are the important parts of my code:

以下是我的代码的重要部分：

File: app/start/global.php

文件：app/start/global.php

<?php

// ...

App::bind('Acme\Interfaces\HelpersInterface', 'Acme\Services\Helpers');

File: composer.json

文件：composer.json

// ...

"autoload": {
    // ...
    "psr-0": {
        "Acme": "app/"
    }
},

// ...

File: app/Acme/Controllers/BaseController.php

文件：app/Acme/Controllers/BaseController.php

<?php namespace Acme\Controllers;

use Carbon\Carbon;
use Controller;
use Illuminate\Foundation\Application as App;
use Illuminate\View\Factory as View;
use Acme\Interfaces\HelpersInterface as Helpers;
use Illuminate\Http\Response;

class BaseController extends Controller {

    /**
     * @var \Illuminate\Foundation\Application
     */
    private $app;

    /**
     * @var \Carbon\Carbon
     */
    private $carbon;

    /**
     * @var \Illuminate\View\Factory
     */
    private $view;

    /**
     * @var \Acme\Interfaces\HelpersInterface
     */
    private $helpers;

    function __construct(App $app, Carbon $carbon, View $view, Helpers $helpers)
    {
        $this->app = $app;
        $this->carbon = $carbon;
        $this->view = $view;
        $this->helpers = $helpers;

        $lang = $this->app->getLocale();
        $now = $this->carbon->now();

        $this->view->share('lang', $lang);
        $this->view->share('now', $now);
    }

    /**
     * Missing Method
     *
     * Abort the app and return a 404 response
     *
     * @param array $parameters
     * @return Response
     */
    public function missingMethod($parameters = array())
    {
        return $this->helpers->force404();
    }

}

File: app/Acme/Services/Helpers.php

文件：app/Acme/Services/Helpers.php

<?php namespace Acme\Services;

use Illuminate\Config\Repository as Config;
use Illuminate\Database\Connection as DB;
use Illuminate\Http\Request;
use Illuminate\Routing\Redirector as Redirect;
use Illuminate\Session\Store as Session;
use Illuminate\Support\Facades\Response;
use Illuminate\Translation\Translator as Lang;
use Illuminate\View\Factory as View;
use Acme\Interfaces\MockablyInterface;
use Monolog\Logger as Log;

class Helpers implements HelpersInterface {

// ...

    public function __construct(
        Config $config,
        Lang $lang,
        View $view,
        MockablyInterface $mockably,
        Log $log,
        Request $request,
        Session $session,
        DB $db,
        Redirect $redirect,
        Response $response
    ) {
        // ...
    }

// ...

}

File: app/Acme/Providers/HelpersServiceProvider.php

文件：app/Acme/Providers/HelpersServiceProvider.php

<?php namespace Acme\Providers;

use Illuminate\Support\ServiceProvider;
use Acme\Services\Helpers;

class HelpersServiceProvider extends ServiceProvider {

private $db;
private $defaultDbConnection;

protected function init()
{
    $this->db = $this->app['db'];
    $this->defaultDbConnection = $this->db->getDefaultConnection();
}

public function register()
{
    $this->init();

    $this->app->bind('helpers', function ()
    {
        return new Helpers(
            $this->app['config'],
            $this->app['translator'],
            $this->app['view'],
            $this->app['mockably'],
            $this->app->make('log')->getMonolog(),
            $this->app['request'],
            $this->app['session.store'],
            $this->db->connection($this->defaultDbConnection),
            $this->app['redirect'],
            $this->app['Illuminate\Support\Facades\Response']
        );
    });
}

回答by Joseph Silber

It seems your Acme\Services\Helpersconstructor takes a $nameparameter, but is not type hinted.

似乎您的Acme\Services\Helpers构造函数接受一个$name参数，但没有类型提示。

Laravel's IoC is not magic. If your don't provide a type hint for every parameter, the IoC container has no way of knowing what to pass in.

Laravel 的 IoC 并不神奇。如果您没有为每个参数提供类型提示，则 IoC 容器无法知道要传入什么。

回答by CIRCLE

For me it was just a matter of running

对我来说这只是跑步的问题

php artisan optimize:clear

回答by Martin

Got it fixed. All the tutorials about dependency injection were referring to concrete implementations of interfaces so that I thought that's the way to go about it. Joseph Silber'sanswer got me on the right track.

搞定了 所有关于依赖注入的教程都指的是接口的具体实现，所以我认为这是解决问题的方法。Joseph Silber's答案让我走上正轨。

The trick is to bind the Interface to the binding of the ServiceProviderlike shown below. That way Laravel will know how to instantiate the Helpers service.

诀窍是将接口绑定到ServiceProvider如下所示的绑定。这样 Laravel 就会知道如何实例化 Helpers 服务。

File: app/start/global.php

文件：app/start/global.php

<?php

// ...

App::bind('Acme\Interfaces\HelpersInterface', 'helpers');