update code

app/Http/Requests/Attachment/CreateRequest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Http\Requests\Attachment;
+
+use Illuminate\Foundation\Http\FormRequest;
+use App\Entities\Document;
+
+class CreateRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     *
+     * @return bool
+     */
+    public function authorize()
+    {
+        return Document::find($this->document_id)->creator_id == $this->user()->id;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     *
+     * @return array
+     */
+    public function rules()
+    {
+        return [
+            'document_id' => 'required|exists:documents,id',
+            'attachments' => 'required|file',
+        ];
+    }
+}