The Default Validation Setup

Let’s begin with a simple example of a Laravel controller for handling cart items. In this example, we have a ‘store’ method that validates the ‘qty’ and ‘productId’ fields:

<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;

class CartItemsController extends Controller
{
    public function store()
    {
        request()->validate([
            'qty' => ['required', 'integer', 'min:10'],
            'productId' => ['required', 'exists:products,id']
        ]);
    }
}

The validation rules here are quite straightforward, but there’s room for improvement in the error messages that users might encounter.

Customizing Error Messages

1. Descriptive Language

The first issue we notice is that the error message for the ‘qty’ field uses the abbreviation ‘qty.’ While developers might understand this, it’s not very user-friendly. We should replace ‘qty’ with ‘quantity’ in the error message. You can customize error messages by passing a second array as an argument, where keys are formed using the name of the parameter and the name of the validation rule. The value will be the error message you want to display:

<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;

class CartItemsController extends Controller
{
    public function store()
    {
        request()->validate([
            'qty' => ['required', 'integer', 'min:10'],
            'productId' => ['required', 'exists:products,id']
        ], [
            'qty.min' => 'The quantity must be at least :min.',
            'productId.exists' => 'The product is no longer available.'
        ]);
    }
}

By customizing the error messages, we now provide a clear and descriptive message to the user, making it easier for them to understand what went wrong.

2. Using Form Request Objects

While the above approach works perfectly well, you can achieve the same results using form request objects in Laravel. Form request objects encapsulate the validation rules, and you can include a ‘messages’ method to specify custom error messages. Here’s an example:

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;

class StoreCartItemRequest extends FormRequest
{
    public function authorize()
    {
        return true;
    }

    public function rules()
    {
        return [
            'qty' => ['required', 'integer', 'min:10'],
            'productId' => ['required', 'exists:products,id']
        ];
    }

    public function messages()
    {
        return [
            'qty.min' => 'The quantity must be at least :min.',
            'productId.exists' => 'The product is no longer available.'
        ];
    }
}

Using form request objects can make your code cleaner and more organized, especially when dealing with multiple validation rules and messages.