Undefined index: title in laravel

public function store(Request $request) {

    $data      = $request->only('title','body');
    $data      = str_slug($data['title']);
    $data      = Auth::user()->id;
    $post      = Post::create($data);
    return redirect()->route('edit_post',['id'=>$post->id]);
}

in postController.php

via Chebli Mohamed