Touching Parent Timestamps

When a model defines a belongsTo or belongsToMany relationship to another model, such as a Comment which belongs to a Post, it is sometimes helpful to update the parent's timestamp when the child model is updated.

For example, when a Comment model is updated, you may want to automatically "touch" the updated_at timestamp of the owning Post so that it is set to the current date and time. To accomplish this, you may add a touches property to your child model containing the names of the relationships that should have their updated_at timestamps updated when the child model is updated:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;

class Comment extends Model
{
    /**
     * All of the relationships to be touched.
     *
     * @var array
     */
    protected $touches = ['post'];

    /**
     * Get the post that the comment belongs to.
     */
    public function post(): BelongsTo
    {
        return $this->belongsTo(Post::class);
    }
}

WARNING

Parent model timestamps will only be updated if the child model is updated using Eloquent's save method.