无法解析的依赖解析 [Parameter #0 [ <required&

问题描述

警告:这个问题是针对 Laravel 4 的.

Warning: This question is Laravel 4 specific.

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.

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.

重构控制器后出现以下错误:

After refactoring the controller I get following error:

照亮容器BindingResolutionException

Illuminate Container BindingResolutionException

无法解析的依赖解析 [Parameter #0 [ $name ]].

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

我不知道问题出在哪里.错误消息对我来说似乎很神秘，我不明白.(我没有发现 __constructor 参数有任何问题，因为我已经为 HelpersInterface 注册了绑定)

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 __constructor parameters since I've registered the binding for the HelpersInterface)

以下是我的代码的重要部分:

Here are the important parts of my code:

文件:app/start/global.php

<?php
 
// ...
 
App::bind('AcmeInterfacesHelpersInterface', 'AcmeServicesHelpers');

文件:composer.json

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

文件:app/Acme/Controllers/BaseController.php

<?php namespace AcmeControllers;
 
use CarbonCarbon;
use Controller;
use IlluminateFoundationApplication as App;
use IlluminateViewFactory as View;
use AcmeInterfacesHelpersInterface as Helpers;
use IlluminateHttpResponse;
 
class BaseController extends Controller {
 
    /**
     * @var IlluminateFoundationApplication
     */
    private $app;
 
    /**
     * @var CarbonCarbon
     */
    private $carbon;
 
    /**
     * @var IlluminateViewFactory
     */
    private $view;
 
    /**
     * @var AcmeInterfacesHelpersInterface
     */
    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();
    }
 
}

文件:app/Acme/Services/Helpers.php

<?php namespace AcmeServices;

use IlluminateConfigRepository as Config;
use IlluminateDatabaseConnection as DB;
use IlluminateHttpRequest;
use IlluminateRoutingRedirector as Redirect;
use IlluminateSessionStore as Session;
use IlluminateSupportFacadesResponse;
use IlluminateTranslationTranslator as Lang;
use IlluminateViewFactory as View;
use AcmeInterfacesMockablyInterface;
use MonologLogger 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
    ) {
        // ...
    }

// ...

}

文件:app/Acme/Providers/HelpersServiceProvider.php

<?php namespace AcmeProviders;

use IlluminateSupportServiceProvider;
use AcmeServicesHelpers;

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['IlluminateSupportFacadesResponse']
        );
    });
}

推荐答案

看起来你的 AcmeServicesHelpers 构造函数接受了一个 $name 参数，但不是类型暗示.

It seems your AcmeServicesHelpers constructor takes a $name parameter, but is not type hinted.

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

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.

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