Laravel Model Callbacks After Save, Before Save, etc

laravel model callbacks after save, before save, etc

Actually, Laravel has real callback before|after save|update|create some model. check this:

https://github.com/laravel/laravel/blob/3.0/laravel/database/eloquent/model.php#L362

the EventListener like saved and saving are the real callbacks

$this->fire_event('saving'); 

$this->fire_event('saved');

how can we work with that? just assign it to this eventListener example:

 \Laravel\Event::listen('eloquent.saving: User', function($user){
  $user->saving();//your event or model function
});

Laravel: how to create a function After or Before save|update

Inside your model, you can add a boot() method which will allow you to manage these events.

For example, having User.php model:

class User extends Model 
{

    public static function boot()
    {
        parent::boot();

        self::creating(function($model){
            // ... code here
        });

        self::created(function($model){
            // ... code here
        });

        self::updating(function($model){
            // ... code here
        });

        self::updated(function($model){
            // ... code here
        });

        self::deleting(function($model){
            // ... code here
        });

        self::deleted(function($model){
            // ... code here
        });
    }

}

You can review all available events over here: https://laravel.com/docs/5.2/eloquent#events

how to know if laravel model values changed on save callback

You can use the isDirty() method which returns a bool and getDirty() which returns an array with the changed values.

public function save(array $options = array())
{
    $changed = $this->isDirty() ? $this->getDirty() : false;

    // before save code
     parent::save();

    // Do stuff here
    if($changed)
    {
        foreach($changed as $attr)
        {
            // My logic
        }
    }

}

What's the most reliable way to catch saves and deletes in Laravel 5.2?

The three methods and 4th referred by @joko. There may be more as well but lets focus on the 4 methods.

Let me describe you them one by one:

1) Override the save and delete methods on the model

In this method you are using OOPD method overriding. You are overriding Laravel's interal save method and adding your additional code by defining your own save method on top of it. This should be avoided as Laravel keep evolving and it may happen that thing start to fail if major change is done like Suppose in future laravel replace save method with any other method to save the records. Then again you will have to create another method to override that new method. Also writing code here may grow your model class file. You model may keep handling things like he shouldn't handle(Example: Sending Email). This method should be avoided.

2) Add creating/updating/deleting callbacks in the boot method

Here you are defining code on the Boot method of the Model. This method should only be used if there is much little code/things that you need to handle on event. The drawback of this method is that it make code more complicated and cluttered as you may write all logic in one like like functional programming. Suppose if you have to do some stuff on before creating and after created. You boot method will grow.

3) Bind an observer in the boot method

This method is pretty good. You create one observer class which handles such stuff that what should happen on Laravel events. It makes code more cleaner and easy to maintain.

Example: Suppose you have to write code in creating, saving, saved, deleting in these methods. In this case, method 1) and method 2) won't be good practice because in

Method 1: We will have to create this 4 methods and override them as well and support them in future releases of Laravel. In this case, code in your Model will also grow because of overriding this methods

Method 2: In this case your boot method will grow as well so you Model file will become a junk of code.

In method 1 and 2 also remember that its not responsibility of your Model to do many of the stuff that you going to write. Like sending email when user is created. These codes you may end up writing in created method.

Suppose now you have scenario where you need to send email to user on created event as well as you need to make user's entry log user in customer CRM. then you will have to write code for both in same method. Probably, you may not following single responsibility principle there. What should we do in the case? See method 4.

4) Other method suggested by @joko

The scenario that i suggested in method 4's end. You may send email to user and log him in Customer CRM whenever it is created. Then your method will do 2 things(Sending email and logging in CRM). It may not following single responsibility principle. What if better we can decouple both of them. Then comes this method.

class EventServiceProvider extends ServiceProvider
{
    /**
     * The event listener mappings for the application.
     *
     * @var array
     */
    protected $listen = [
        'eloquent.saved: App\User' => 'App\Listeners\SendWelcomeEmailToUser'
        'eloquent.saved: App\User' => 'App\Listeners\LogUserInCRM'
    ];
}

Create two listener classes:

class SendWelcomeEmailToUser
{
    public function handle(User $user){
        // Write code to send email
    }
}

class LogUserInCRM
{
    public function handle(User $user){
        // Write code to log
    }
}

Through this you can separate out codes and make them more cleaner.

I generally prefer this method its mode clean. It also gives you much better idea that what actually happen when event happens. It becomes one single point for Event to Listener mapping.

How to access model attribute from an overrided eloquent save() method? (converting empty input to null)

You should be able to access it using $this:

class Page extends Eloquent {

   public function save()
   {
      $this->sanitize();

      parent::save();
   }

   public function sanitize()
   {
      foreach($this->getAttributes() as $key => $value)
      {
         if ( ! $value)
         {
             $this->{$key} = null;
         }
      }   
   }
}

This is untested code, but should work.

Laravel Update Eloquent Field automatically on save

So i think i have the answer here. it is two folds:

1. in the event callback you need to update the field in question using the $model->setAttribute($field, $value); function.
2. in my generateSku function i was relying on the models relationships to get names etc from child relationships; however on the even the models relationships had not updated at this time, thus the function was using old relationships. Changing this to use the data from the model/table that was being updated rather than its relationships had the desired effect.

All in all the event code now looks like this:

static::saving(function ($model) {
        CustomLog::debug(__CLASS__, __FUNCTION__, __LINE__, 'saving model fired');
        $model->setAttribute('sku', static::generateSku($model));
    });

Ignore the updated event when an Eloquent model is restored

The trait HasLogs adds a Boolean attribute to the Model named loggableIsBeingRestored set to false by default.

The trait also registers a new listener for restoring which sets loggableIsBeingRestored to true at the begging of the described actions.

Then the updated listener checks for loggableIsBeingRestored before proceeding with its actions.

trait HasLogs
{
    public bool $loggableIsBeingRestored = false;

    public static function bootHasLogs(): void
    {
        // ...

        self::updated(callback: function ($model) {
            if (isset($model->loggableIsBeingRestored) && $model->loggableIsBeingRestored) {
                // This is a restored event so don't log!
                return;
            }

            self::log($model, 'updated');
        });

        // ...

        self::restored(callback: function ($model) {
            self::log($model, 'restored');

            $model->loggableIsBeingRestored = false;
        });

        self::restoring(callback: function ($model) {
            $model->loggableIsBeingRestored = true;
        });
    }
    // ...
}

How to save NOW() to the same field in my Laravel Eloquent model every time I save?

You can accomplish this in the saving event, for which you can register a callback in you model's boot method:

class User extends Eloquent {

    public static function boot()
    {
        static::saving(function($user)
        {
            $user->modified = DB::raw('NOW()');

            // Alternatively, you can use this:
            $user->modified = Carbon\Carbon::now();
        });

        parent::boot();
    }

}

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