invoiceninja/app/Http/Requests/Expense/StoreExpenseRequest.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com).
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Http\Requests\Expense;

use App\Http\Requests\Request;
use App\Http\ValidationRules\Expense\UniqueExpenseNumberRule;
use App\Models\Expense;
use App\Utils\Traits\MakesHash;
use Illuminate\Validation\Rule;

class StoreExpenseRequest extends Request
{
    use MakesHash;

    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize() : bool
    {
        return auth()->user()->can('create', Expense::class);
    }

    public function rules()
    {
        $rules = [];

        if ($this->number) 
            $rules['number'] = Rule::unique('expenses')->where('company_id', auth()->user()->company()->id);
        
        if(!empty($this->client_id))
            $rules['client_id'] = 'bail|sometimes|exists:clients,id,company_id,'.auth()->user()->company()->id;

        return $this->globalRules($rules);
    }

    protected function prepareForValidation()
    {
        $input = $this->all();

        $input = $this->decodePrimaryKeys($input);

        if (array_key_exists('category_id', $input) && is_string($input['category_id'])) {
            $input['category_id'] = $this->decodePrimaryKey($input['category_id']);
        }

        if (! array_key_exists('currency_id', $input) || strlen($input['currency_id']) == 0) {
            $input['currency_id'] = (string)auth()->user()->company()->settings->currency_id;
        }

        if(array_key_exists('color', $input) && is_null($input['color']))
            $input['color'] = '#fff';

        $this->replace($input);
    }

    public function messages()
    {
        return [
            'unique' => ctrans('validation.unique', ['attribute' => 'email']),
        ];
    }
}