'nullable|string|max:255', 'student_id' => 'required|integer|exists:students,id', 'file' => $this->isMethod('POST') ? 'required|file|mimes:jpeg,png,gif,pdf,mp4,mov,avi|max:20480' : 'sometimes|file|mimes:jpeg,png,gif,pdf,mp4,mov,avi|max:20480', ]; } }