invoiceninja/app/Http/Requests/CreateDocumentRequest.php

<?php namespace App\Http\Requests;

use App\Models\Invoice;
use App\Models\Expense;

class CreateDocumentRequest extends DocumentRequest
{
    protected $autoload = [
        ENTITY_INVOICE,
        ENTITY_EXPENSE,
    ];

    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        if ( ! $this->user()->hasFeature(FEATURE_DOCUMENTS)) {
            return false;
        }
        
        if ($this->invoice && $this->user()->cannot('edit', $this->invoice)) {
            return false;
        }

        if ($this->expense && $this->user()->cannot('edit', $this->expense)) {
            return false;
        }

        return $this->user()->can('create', ENTITY_DOCUMENT);
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            //'file' => 'mimes:jpg'
        ];
    }

}