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

This only works after an event happened on your model.

Method 1, using Observers

Create an observer for your model

php artisan make:observer UserObserver --model=User

this will create an event observer on your model

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

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

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

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

You must register this observer in the boot method on one of your ServiceProviders preferably the AppServiceProvider

// App\Providers\AppServiceProvider.php

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

Method 2, using Closures

You can register custom events in the static booted method of your model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class User extends Model
{
    /**
     * The "booted" method of the model.
     *
     * @return void
     */
    protected static function boot()
    {
        parent::boot();
        static::created(function ($user) {
            //
        });
    }
}

Available observable events

// Illuminate\Database\Eloquent\Concerns

/**
 * Get the observable event names.
 *
 * @return array
 */
public function getObservableEvents()
{
    return array_merge(
        [
            'retrieved', 'creating', 'created', 'updating', 'updated',
            'saving', 'saved', 'restoring', 'restored', 'replicating',
            'deleting', 'deleted', 'forceDeleted', 'trashed'
        ],
        $this->observables
    );
}

Note from Laravel documentation

When issuing a mass update via Eloquent, the saving, saved, updating, and updated model events will not be fired for the updated models. This is because the models are never actually retrieved when issuing a mass update.

Create a provider by using this command

php artisan make:provider ProviderClassName

then define the callbacks for models in boot function

Model::created(function($model){
  //Do you want to do
});

List of available callbacks:

Model::creating(function($model){});
Model::updated(function($model){});
Model::updating(function($model){});
Model::deleted(function($model){});
Model::deleting(function($model){});
Model::saving(function($model){});
Model::saved(function($model){});