Laravel Model Events - I'm a bit confused abou

Question

So the way I see it is that a good Laravel application should be very model- and event-driven.

I have a Model called Article. I wish to send email alerts when the following events happen:

• When an Article is created
• When an Article is updated
• When an Article is deleted

The docs say I can use Model Events and register them within the boot() function of App\Providers\EventServiceProvider.

But this is confusing me because...

• What happens when I add further models like Comment or Author that need full sets of all their own Model Events? Will the single boot() function of EventServiceProvider just be absolutely huge?
• What is the purpose of Laravel's 'other' Events? Why would I ever need to use them if realistically my events will only respond to Model CRUD actions?

I am a beginner at Laravel, having come from CodeIgniter, so trying to wrap my head around the proper Laravel way of doing things. Thanks for your advice!

Answer 1

Recently I came to same problem in one of my Laravel 5 project, where I had to log all Model Events. I decided to use Traits. I created ModelEventLogger Trait and simply used in all Model class which needed to be logged. I am going to change it as per your need Which is given below.

<?php

namespace App\Traits;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\Event;

/**
 * Class ModelEventThrower 
 * @package App\Traits
 *
 *  Automatically throw Add, Update, Delete events of Model.
 */
trait ModelEventThrower {

    /**
     * Automatically boot with Model, and register Events handler.
     */
    protected static function bootModelEventThrower()
    {
        foreach (static::getModelEvents() as $eventName) {
            static::$eventName(function (Model $model) use ($eventName) {
                try {
                    $reflect = new \ReflectionClass($model);
                    Event::fire(strtolower($reflect->getShortName()).'.'.$eventName, $model);
                } catch (\Exception $e) {
                    return true;
                }
            });
        }
    }

    /**
     * Set the default events to be recorded if the $recordEvents
     * property does not exist on the model.
     *
     * @return array
     */
    protected static function getModelEvents()
    {
        if (isset(static::$recordEvents)) {
            return static::$recordEvents;
        }

        return [
            'created',
            'updated',
            'deleted',
        ];
    }
} 

Now you can use this trait in any Model you want to throw events for. In your case in Article Model.

<?php namespace App;

use App\Traits\ModelEventThrower;
use Illuminate\Database\Eloquent\Model;

class Article extends Model {

    use ModelEventThrower;

    //Just in case you want specific events to be fired for Article model
    //uncomment following line of code

   // protected static $recordEvents = ['created'];

}

Now in your app/Providers/EventServiceProvider.php, in boot() method register Event Handler for Article.

 public function boot(DispatcherContract $events)
 {
     parent::boot($events);
     $events->subscribe('App\Handlers\Events\ArticleEventHandler');
 }

Now create Class ArticleEventHandler under app/Handlers/Events directory as below,

<?php namespace App\Handlers\Events;

use App\Article;

class ArticleEventHandler{

    /**
     * Create the event handler.
     *
     * @return \App\Handlers\Events\ArticleEventHandler
     */
    public function __construct()
    {
        //
    }

    /**
    * Handle article.created event
    */

   public function created(Article $article)
   {
      //Implement logic
   }

   /**
   * Handle article.updated event
   */

   public function updated(Article $article)
   {
      //Implement logic
   }

  /**
  * Handle article.deleted event
  */

  public function deleted(Article $article)
  {
     //Implement logic
  }

 /**
 * @param $events
 */
 public function subscribe($events)
 {
     $events->listen('article.created',
            'App\Handlers\Events\ArticleEventHandler@created');
     $events->listen('article.updated',
            'App\Handlers\Events\ArticleEventHandler@updated');
     $events->listen('article.deleted',
            'App\Handlers\Events\ArticleEventHandler@deleted');
 }

}

As you can see from different answers, from different Users, there are more than 1 way of handling Model Events. There are also Custom events That can be created in Events folder and can be handled in Handler folder and can be dispatched from different places. I hope it helps.

Answer 2

1) You may create an event listener for each new Model (ArticleEventSubscriber,CommentEventSubscriber) at boot method:

EventServiceProvider.php

public function boot(DispatcherContract $events)
{
    parent::boot($events);

    $events->subscribe('App\Listeners\ArticleEventListener');
    $events->subscribe('App\Listeners\CommentEventListener');
}

or you may also use $subscribe property

protected $subscribe = [
        'App\Listeners\ArticleEventListener',
        'App\Listeners\CommentEventListener',
    ];

There are many ways to listen and handle events. Take a look to current master documentation for discovering more ways(like usings closures) to do so : Laravel Docs (master) and this other answer

2) Model events are just events provided by default by Eloquent.

https://github.com/illuminate/database/blob/491d58b5cc4149fa73cf93d499efb292cd11c88d/Eloquent/Model.php#L1171

https://github.com/illuminate/database/blob/491d58b5cc4149fa73cf93d499efb292cd11c88d/Eloquent/Model.php#L1273