初窥Laravel模型观察者

如果想在一个模型中监听多个事件，那么你可以把它写成一个类，类中的方法名称即是你想要监听的事件名称。

阅读之前建议看下Laravel模型事件模型的事件观察者是模型的高级应用，我们不局限于将模型事件书写在模型中，可以使用模型观察者将相应事件独立出来。

创建观察者类，类所在目录：app\Observers下，命名为：PostObservers

数据准备

命令行执行如下命令：

laravel new laravel-model-observers
cd laravel-model-observers
php artisan make:model Post -m
touch database/database.sqlite

上面的命令会创建一个Laravel项目并创建一个Post模型文件和对应的迁移文件与数据库配置文件。

修改项目本地环境文件.env文件中的数据库连接

DB_CONNECTION=sqlite

修改数据库迁移文件database\migrations\****_**_**_******_create_posts_table.php中的 up()方法

public function up()
{
    Schema::create('posts', function (Blueprint $table) {
        $table->increments('id');
        $table->string('title');
        $table->text('body');
        $table->softDeletes();
        $table->timestamps();
    });
}

修改好迁移文件之后，执行迁移

php artisan migrate

模型内容

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Post extends Model
{
    use SoftDeletes;
    protected $fillable = [
        'title', 'body',
    ];

    public static function boot()
    {
        parent::boot();
        static::observe(new \App\Observers\PostObserver());
    }
}

使用类的boot()静态方法注册模型观察者类。

观察者类

<?php
namespace App\Observers;

class PostObserver
{
    // 新增模型数据触发
    public function creating($post) {
        echo "creating event is fired\n";
    }

    // 新增模型数据触发
    public function created($post) {
        echo "created event is fired\n";
    }

    // 编辑模型数据触发
    public function updating($post) {
        echo "updating event is fired\n";
    }

    // 编辑模型数据触发
    public function updated($post) {
        echo "updated event is fired\n";
    }

    // 新增、编辑模型数据触发
    public function saving($post) {
        echo "saving event is fired\n";
    }

    // 新增、编辑模型数据触发
    public function saved($post) {
        echo "saved event is fired\n";
    }

    // 删除模型数据触发
    public function deleting($post) {
        echo "deleting event is fired\n";
    }

    // 删除模型数据触发
    public function deleted($post) {
        echo "deleted event is fired\n";
    }

    // 监听数据即将从软删除状态恢复的事件。
    public function restoring($post)
    {
        echo "restoring event is fired\n";
    }

    // 监听数据从软删除状态恢复后的事件。
    public function restored($post)
    {
        echo "restored event is fired\n";
    }
}

注意: 如果 saving/creating/updating/deleting/restoring 事件逻辑中返回false，则相应的创建/更新/删除操作会退出，不再往下执行。 其中restoring和restored事件需要模型 use Illuminate\Database\Eloquent\SoftDeletes;才能正常使用。

在Tinker中测试

增

☁  laravel-model-observers [master] ⚡ tinker
Psy Shell v0.8.17 (PHP 7.1.13 — cli) by Justin Hileman
>>> App\Post::create(['title'=>'title', 'body'=>'Body']);
saving event is fired
creating event is fired
created event is fired
saved event is fired
=> App\Post {#753
     title: "title",
     body: "Body",
     updated_at: "2018-01-16 08:30:08",
     created_at: "2018-01-16 08:30:08",
     id: 1,
   }
>>>

通过执行上面的代码我们可以看到，执行模型create()方法，会依次触发saving、creating、created 和 saved 事件。

删

☁ laravel-model-observers [master] ⚡ tinker
Psy Shell v0.8.17 (PHP 7.1.13 — cli) by Justin Hileman
>>> App\Post::destroy(1)
deleting event is fired
deleted event is fired
=> 1

通过执行上面的删除代码，我们可以看到会依次触发deleting和deleted事件。

>>> $post = Post::find(1)
=> App\Post {#770
     id: "1",
     title: "title",
     body: "Body",
     deleted_at: null,
     created_at: "2018-01-16 09:26:50",
     updated_at: "2018-01-16 09:26:50",
   }
>>> $post->restore();
restoring event is fired
saving event is fired
updating event is fired
updated event is fired
saved event is fired
restored event is fired

通过执行上面的恢复删除代码，可以依次触发了restoring、saving、updating、updated、saved和restored事件中的代码

改

☁  laravel-model-observers [master] ⚡ tinker
Psy Shell v0.8.17 (PHP 7.1.13 — cli) by Justin Hileman
>>> $post = App\Post::first();
=> App\Post {#752
     id: "2",
     title: "title",
     body: "Body",
     created_at: "2018-01-16 08:31:30",
     updated_at: "2018-01-16 08:31:30",
   }
>>> $post->title = 'New Title'
=> "New Title"
>>> $post->save();
saving event is fired
updating event is fired
updated event is fired
saved event is fired
=> true

通过执行上面的代码，我们可以看到会依次触发saving updating updated 和 saved 事件。