jcergolj/request-input-transformer-for-laravel

A Laravel package for transforming request inputs

v1.0 2025-05-28 12:13 UTC

Requires (Dev)

• larastan/larastan: ^3.0
• laravel/pint: ^1.9
• orchestra/testbench: ^10.0
• phpunit/phpunit: ^12.1

MIT

• Janez Cergolj

README

Clean up your prepareForValidation() — the right way.

Why?

If you’ve built more than a couple of Laravel apps, you’ve probably ended up stuffing too much logic into prepareForValidation().

Maybe you’ve written code like this:

protected function prepareForValidation(): void
{
    $this->merge([
        'email' => Str::of($this->email)->trim()->lower()->toString(),
        'first_name' => Str::of($this->first_name)->trim()->ucfirst()->toString(),
        'last_name' => Str::of($this->last_name)->trim()->ucfirst()->toString(),
        //...
    ]);
}

We've all been there — a quick trim() here, a lower() there. But soon, prepareForValidation() is packed with string cleanup, formatting, and conditionals.

This package solves this.

Installation

composer require jcergolj/request-input-transformer-for-laravel

Under the Hood: Pipeline Pattern

This package uses Laravel’s Pipeline Pattern under the hood.

That means your modifiers and transformers are run one by one, just like middleware — each one gets the current value (or request), does its thing, and passes it to the next.

Modifiers vs Transformers

This package gives you two ways to work with request input: modifiers and transformers.

🛠 Modifiers

Modifiers change values of existing fields in the request — great for cleanup and normalization.

// Modifying the 'email' field
'email' => [new Trim(), new Lowercase()],

Use modifiers when the field already exists and you need to modify only that field .

Modifiers merges fields automatically inside pipeline then method.

🔄 Transformers

Transformers have access to the entire request and can add or change fields based on logic, relationships, or conditions.

new AddFullName(),
new RemoveItemIfEmpty(),

Use transformers when you need to generate new fields or apply logic that involves more than one input.

Nested Input Support

This package supports nested input keys — including wildcard syntax — out of the box. You can apply modifiers or transformers to fields like:

'members.*.email' => [new Trim()],

Usage

Step 1: Create a Modifier and Transformer

Modifier: Trim strings

namespace App\Http\Modifiers;

class Trim
{
    public function handle($value, $next)
    {
        return $next(trim($value));
    }
}

Transformer: Generate a full name from first and last name

<?php

namespace App\Http\Transformers;

class FullNameTransformer
{
    public function handle($request, $next)
    {
        $request->merge([
            'full_name' => "{$request->first_name} {$request->last_name}",
        ]);

        return $next($request);
    }
}

Step 2: Apply in a FormRequest

<?php

use App\Http\Modifiers\Trim;
use App\Http\Modifiers\toLowercase;
use App\Http\Transformers\FullNameTransformer;
use Illuminate\Foundation\Http\FormRequest;
use Jcergolj\RequestPreprocessor\Facades\RequestPreprocessorFacade;

class MyFormRequest extends FormRequest
{
    protected function prepareForValidation()
    {
        RequestPreprocessorFacade::make($this, [
            'email'      => [new Trim(), new toLowercase(), // other modifiers],
            'first_name' => [new Trim()],
            'last_name'  => [new Trim()],
        ],
        [
            new FullNameTransformer(),
            /* other transformers */
        ])->apply();
    }
}

Generating Modifiers and Transformers

To quickly create modifier or transformer classes, you can use the included Artisan commands:

php artisan make:modifier TrimModifier
php artisan make:transformer FullNameTransformer

Testing

What about testing modifiers and transformers?

One of the challenges with prepareForValidation() is that Laravel doesn't offer a clean way to test if it actually ran — especially when you're trying to do as much on a unit level as possible.

I initially tried building custom PHPUnit assertions that would inspect the applied modifiers and transformers, but it quickly became complicated.

My current workaround

A practical alternative is to expose two public methods inside your FormRequest class — one returning modifiers, the other transformers — and then test those separately.

Example:

class MyFormRequest extends FormRequest
{
    public function modifiers(): array
    {
        return [
            'email' => [new Trim()],
        ];
    }

    public function transformers(): array
    {
        return [
            new FullNameTransformer(),
        ];
    }

    protected function prepareForValidation()
    {
        RequestPreprocessorFacade::make($this, $this->modifiers(), $this->transformers())->apply();
    }
}

Now in your test, you can do something like this:

public function test_my_form_request_defines_expected_modifiers()
{
    $request = new MyFormRequest();

    $this->assertEquals(
        [new Trim()],
        $request->modifiers()['email']
    );
}

This doesn’t guarantee that RequestPreprocessor was actually called inside prepareForValidation() — but it does confirm the configuration.

Mocking the RequestPreprocessor in Tests

Something that I haven't tried but it might actually work is using reflection for prepareForValidation and to mock RequestPreprocessorFacade.

Something like this.

use Jcergolj\RequestPreprocessor\Facades\RequestPreprocessorFacade;
use Tests\TestCase;

class MyFormRequestTest extends TestCase
{
    public function test_prepareForValidation_calls_preprocessor()
    {
        // Arrange: mock the facade
        RequestPreprocessorFacade::shouldReceive('make')
            ->once()
            ->withArgs(function ($request, $modifiers, $transformers) {
                // Optionally assert $request is the FormRequest instance
                // and $modifiers contain expected keys/classes
                return $request instanceof \App\Http\Requests\MyFormRequest
                    && isset($modifiers['email']);
            })
            ->andReturnSelf();

        RequestPreprocessorFacade::shouldReceive('apply')
            ->once()
            ->andReturnNull();

        // Act: instantiate and call prepareForValidation
        $request = new \App\Http\Requests\MyFormRequest();

        $reflection = new \ReflectionMethod($request, 'prepareForValidation');
        $reflection->setAccessible(true);
        $reflection->invoke($request);
    }
}

Testing

To run the tests:

composer test

License

The MIT License (MIT).