如何在Laravel中使用触发器？ [英] How to use triggers in laravel?

问题描述

我的代码，使用PHP工匠制作：migration create_trigger命令

My code, using PHP artisan make: migration create_trigger command

public function up()
{
  DB::unprepared(' 
  CREATE TRIGGER roll_no BEFORE INSERT ON `students` FOR EACH ROW 
  BEGIN 
  SET @roll_num = IFNULL((substring((SELECT student_roll_no FROM students WHERE
    class_code = NEW.class_code ORDER BY created_at DESC LIMIT 1),-2) + 1), `1`),
    NEW.student_roll_no = CONCAT(
    YEAR(CURRENT_DATE),
    NEW.class_code,
    IF (@roll_num < 10, CONCAT(`0`, @roll_num), @roll_num) 
  )
  END;
  ');
}

推荐答案

您不需要为模型事件创建迁移。 Laravel雄辩的事件具有多个事件，例如被检索，创建，创建，更新，更新，保存，保存，删除，删除，还原，恢复，您可以轻松地使用它们。

You don't need to create a migration for a model event. Laravel eloquent has multiple events such as retrieved, creating, created, updating, updated, saving, saved, deleting, deleted, restoring, restored that you can easily use them.

首先，您应该像这样为模型创建观察者

first, you should create Observer for your model like this

php artisan make：observer UserObserver --model = User


在UserObserver中，您可以收听任何喜欢的事件，例如：

in the UserObserver you can listen to any event that you like such as:

class UserObserver
{
    /**
     * Handle the User "created" event.
     *
     * @param  \App\User  $user
     * @return void
     */
    public function created(User $user)
    {
        //
    }

    /**
     * Handle the User "updated" event.
     *
     * @param  \App\User  $user
     * @return void
     */
    public function updated(User $user)
    {
        //
    }
}

之后，您应该注册您的观察者以在 app / providers / AppServiceProvider 引导方法中建模，例如：

after that you should register your observer to model in app/providers/AppServiceProvider boot method such as:

public function boot()
{
     User::observe(UserObserver::class);
}

有关详细信息，请访问 Laravel文档。

for more detail visit Laravel documentation.

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