ldc-dam/app/Models/Format.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Format extends Model
{
    /**
     * The attributes that should be cast.
     *
     * @var array
     */
    protected $casts = [
        'largeur' => 'int',
        'hauteur' => 'int',
        'system' => 'bool',
    ];

    /**
     * The sujet that belong to the format.
     */
    public function sujets()
    {
        return $this->belongsToMany('App\Models\Sujet', 'sujets_formats', 'format_id', 'sujet_id');
    }
}