<?php
/**
 * GitScrum v0.1.
 *
 * @author  Renato Marinho <renato.marinho@s2move.com>
 * @license http://opensource.org/licenses/GPL-3.0 GPLv3
 */
namespace GitScrum\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;
use GitScrum\Models\Sprint;

class IssueRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'title' => 'required',
        ];
    }

    protected function getValidatorInstance()
    {
        $data = $this->all();

        if (isset($data['slug_sprint'])) {
            $data['sprint_id'] = Sprint::where('slug', '=', $data['slug_sprint'])->first()->id;
            unset($data['slug_sprint']);
        }

        $this->getInputSource()->replace($data);

        return parent::getValidatorInstance();
    }
}

<?php
/**
 * GitScrum v0.1.
 *
 * @author  Renato Marinho <renato.marinho@s2move.com>
 * @license http://opensource.org/licenses/GPL-3.0 GPLv3
 */
namespace GitScrum\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;
use GitScrum\Models\Sprint;

class IssueRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'title' => 'required',
        ];
    }

    protected function getValidatorInstance()
    {
        $data = $this->all();

        if (isset($data['slug_sprint']) && !empty($data['slug_sprint'])) {
            $data['sprint_id'] = Sprint::where('slug', '=', $data['slug_sprint'])->first()->id;
            unset($data['slug_sprint']);
        }

        $this->getInputSource()->replace($data);

        return parent::getValidatorInstance();
    }
}

Check if array index has content
Check if array index has content
