ldc-legaulois/app/Http/Requests/UpdateRecipe.php

<?php

namespace App\Http\Requests;

class UpdateRecipe extends StoreRecipe
{
    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        $rules = [
            'slug' => 'required|unique:recipes,slug,' . $this->recipe->id . '|min:1|max:255',
        ];
        if ($this->recipe->picture) {
            $rules['picture'] = 'image|mimes:jpeg,png,jpg|max:2048|dimensions:width=683,height=434';
        }
        return array_merge(parent::rules(), $rules);
    }
}