首先,我们为你展示如何通过模型观察者实现前面模式事件中的第一个例子。
在 app/Observers文件夹中创建 WelcomeUserObserver.php文件,并加入下面的代码:
<?php namespace App\Observers; class WelcomeUserObserver { public function created($user){ Mail::send('emails.welcome', ['user' => $user], function($message) use ($user) { $message->to($user->email, $user->first_name . ' ' . $user->last_name)->subject('Welcome to My Awesome App, '.$user->first_name.'!'); }); } }
然后在 EventServiceProvider的 boot()方法中注册该观察者:
/** * Register any other events for your application. * * @param \Illuminate\Contracts\Events\Dispatcher $events * @return void */ public function boot(DispatcherContract $events) { parent::boot($events); User::observe(new WelcomeUserObserver); }
这样就 OK 了!现在你的观察者已经与模型关联起来了。
下面我们假设另一种情况。图书管理员对代码提出了一些新的需求:
- 当添加一个新的作者的时候,每一个用户都收到一条通知
- 每次添加/删除作者的时候,都发送一封邮件
- 最后,每次删除一本书的时候,图书管理员都要知道数据库中有多少作者是没有与相关的图书的
好了,下面我们就开始吧。我们需要三个单独的类(请记住我们的 单一职责原则): CustomerNewAuthorObserver、 LibrarianAuthorObserver、 AuthorsWithoutBooksObservers。
注意:你可以按自己喜欢的方式命名这些类,我们这里只是选择比较容易与所选行为关联起来的名称。
下面我们分别来创建三个类:
<?php // file: app/Observers/CustomerNewAuthorObserver namespace App\Observers; class CustomerNewAuthorObserver { public function created($author) { } }<?php // file: app/Observers/LibrarianAuthorObserver namespace App\Observers; class LibrarianAuthorObserver { public function created($author) { } public function deleted($author) { } }<?php // file: app/Observers/AuthorsWithoutBooksObservers namespace App\Observers; class AuthorsWithoutBooksObservers { public function deleted($author) { } }
好了,现在应该添加一些逻辑了,首先为 CustomerNewAuthorObserver添加:
<?php // file: app/Observers/CustomerNewAuthorObserver namespace App\Observers; class CustomerNewAuthorObserver { public function created($author) { // getting all users... $users = \App\User::all(); foreach($users as $user) { Mail::send('emails.created_author_customer', ['author' => $author], function($message) use ($user) { $message->to($user->email, $user->first_name . ' ' . $user->last_name)->subject('New Author Added!'); }); } } }
注意:我知道这是一种非常简单粗暴的方法,这里只是为了实现上面的目的。实际情况中可以使用 邮件队列。
<?php // file: app/Observers/LibrarianAuthorObserver namespace App\Observers; class LibrarianAuthorObserver { public function created($author) { Mail::send('emails.created_author_librarian', ['author' => $author], function($message) use ($author) { $message->to('librarian@awesomelibrary.com', 'The Librarian')->subject('New Author: ' . $author->first_name . ' ' . $author->last_name); }); } public function deleted($author) { Mail::send('emails.deleted_author_librarian', ['author' => $author], function($message) use ($author) { $message->to('librarian@awesomelibrary.com', 'The Librarian')->subject('New Author: ' . $author->first_name . ' ' . $author->last_name); }); } }
最后:
<?php // file: app/Observers/AuthorsWithoutBooksObservers namespace App\Observers; class AuthorsWithoutBooksObservers { public function deleted($author) { $authorsWithoutBooks = \App\Author::has('books', '=', 0)->get(); if(count($authorsWithoutBooks) > 0){ Mail::send('emails.author_without_books_librarian', ['authorsWithoutBooks' => $authorsWithoutBooks], function($message) { $message->to('librarian@awesomelibrary.com', 'The Librarian')->subject('Authors without Books! A check is required!'); }); } } }
注意:就像前面提过的,我们假定你已经了解了 Laravel 发送邮件的基本知识,没有的话可以到官网学习下相关知识。
到这里并没有结束。你可以在大量的案例和场景中使用 Laravel 的模型事件和模型观察者。举个例子,假设你写博客,你希望每次发布一篇新文章或者更新一篇原有文章的时候,都更新一些站点地图,这时就可以用到观察者。再比如,当添加新书的时候,记录一些东西,也可以用到观察者。
该篇属于专题:《 Laravel 的 Events(事件) 及 Observers(观察者)》
- 下一篇:《 Laravel 的 Events 及 Observers(六) — 总结》
- 上一篇:《 Laravel 的 Events 及 Observers(四) — 模型观察者》

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