public async Task <IActionResult> DeselectTopic([FromRoute] long groupId, [FromRoute] long topicId) { try { if (User.Type() != Type.Student) { return(StatusCode(403, new { msg = "权限不足" })); } await _topicService.DeleteSeminarGroupTopicByIdAsync(groupId, topicId); return(NoContent()); } catch (GroupNotFoundException) { return(StatusCode(404, new { msg = "没有找到该课程" })); } catch (ArgumentException) { return(StatusCode(400, new { msg = "组号格式错误" })); } }