Laravel 5 Form Request data pre-manipulation

in laravel 5.1 you can do that

<?php namespace App\Http\Requests;

class UpdateSettingsRequest extends Request {

public function authorize()
{
    return true;
}

public function rules()
{
    return [];
}

protected function getValidatorInstance()
{
    $data = $this->all();
    $data['date_of_birth'] = 'test';
    $this->getInputSource()->replace($data);

    /*modify data before send to validator*/

    return parent::getValidatorInstance();
}

Since Laravel 5.4, you can use the prepareForValidation method on FormRequest classes.

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;

class StorePostRequest extends FormRequest
{
    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'title' => 'required|max:200',
            'body' => 'required',
            'tags' => 'required|array|max:10',
            'is_published' => 'required|boolean',
            'author_name' => 'required',
        ];
    }

    /**
     * Prepare the data for validation.
     *
     * @return void
     */
    protected function prepareForValidation()
    {
        $this->merge([
            'title' => fix_typos($this->title),
            'body' => filter_malicious_content($this->body),
            'tags' => convert_comma_separated_values_to_array($this->tags),
            'is_published' => (bool) $this->is_published,
        ]);
    }
}

There's a more detailed write-up here: https://sampo.co.uk/blog/manipulating-request-data-before-performing-validation-in-laravel