我有一个 User eloquent 模型，它在其构造函数中接受了 UserMailer 类的一个实例，但我得到了这个错误

Argument 1 passed to User::__construct() must be an instance of TrainerCompare\Mailers\UserMailer, none given, called in /var/www/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 631 and defined

我理解这个错误，但无法弄清楚我做错了什么，但我不太了解命名空间和 Composer 类映射与 psr0 自动加载。我记得使用 composer dump-autoload 所以不是那样

相关文件夹结构

composer.json
app/
  models/
    User.php
  TrainerCompare/
    Mailers/
      Mailer.php
      UserMailer.php
    Services/
      Validation/

composer.json 自动加载部分。当我添加您可以在 TrainerCompare/中看到的验证服务时，psr-0 部分就在那里，这些类工作得很好。我根据我正在遵循的教程将 app/TrainerCompare/Mailers 添加到类映射中以加载邮件程序类

"autoload": {
        "classmap": [
            "app/commands",
            "app/controllers",
            "app/models",
            "app/database/migrations",
            "app/database/seeds",
            "app/tests/TestCase.php",
            "app/tests/helpers",
            "app/TrainerCompare/Mailers"
        ],
        "psr-0":{
            "TrainerCompare": "app/"
        }
    }

用户.php

<?php

use Illuminate\Auth\UserInterface;
use Illuminate\Auth\Reminders\RemindableInterface;
use TrainerCompare\Mailers\UserMailer as Mailer;

class User extends BaseModel implements UserInterface, RemindableInterface
{
    protected $mailer;

    public function __construct(Mailer $mailer)
    {
        $this->mailer = $mailer;
    }
}

邮件程序.php

<?php namespace TrainerCompare\Mailers;

use Mail;

/**
* Email mailing class
*/
abstract class Mailer
{

    public function __construct()
    {
        # code...
    }

    public function sendTo($user, $subject, $view, $data = [])
    {
        Maill::send($view, $data, function ($message) use ($user, $subject) {
            $message->to($user->email)
                    ->subject($subject);
        });
    }
}

UserMailer.php

<?php namespace TrainerCompare\Mailers;

use User;

/**
* User Mailer Class
*/
class UserMailer extends Mailer
{

    public function __construct()
    {
        # code...
    }

    public function welcome($user)
    {
        $view = 'emails.users.welcome';
        $data = [];
        $subject = 'Welcome to Laracsts';

        return $this->sendTo($user, $subject, $view, $data);
    }
}

最佳答案

Eloquent 通过调用在内部(重新)创建自己:

new static

一个例子是创建一个新的查询:

return with(new static)->newQuery();

我不确定在这种情况下自动依赖解析是否有效，它应该总是在 laravel 中工作，但由于它也有自己的构造方法，你必须至少转发对它的调用并支持 $属性参数:

public function __construct(array $attributes = array(), Mailer $mailer)
{
    $this->mailer = $mailer;

    parent::__construct($attributes);
}

编辑

开个issue了解一下:https://github.com/laravel/framework/issues/3862

编辑 2

正如我在评论中所说，您最好创建一个服务，正如您自己指出的那样，这是一个更好的应用程序设计。您不应该使用您的模型来发送电子邮件。接收用户模型(或仅姓名和电子邮件)并将消息发送给该用户的服务将是更好的方式。

Taylor Otwell 在 issue 中给出的答案:

Models aren't really meant to have dependencies injected into them that way. Kind of just the style of ActiveRecord style ORMs I guess. I would suggest passing the User to a Mailer class or something similar. Or if you're comfortable with it you could use App::make to grab an instance of Mail from the model instance, especially if you only need that dependency from a single method.

关于php - 无法将类实例传递给构造函数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22338161/