public async Task <dynamic> OnCreateDiscussionAsync([FromForm] Discussion discussion, [FromForm] string token)
        {
            try
            {
                var t = await tokenService.GetTokenAsync(token);

                if (t == null)
                {
                    throw new Exception("请先登录");
                }
                if (t.Role != UserRole.Admin)
                {
                    var uc = await courseService.GetUserCourseAsync(t.UserID, discussion.CourseId);

                    if (uc == null)
                    {
                        throw new Exception("权限不足");
                    }
                }

                await courseService.AddDiscussionAsync(discussion);

                await eventService.AddDiscussionCreatedEventAsync(discussion.DiscussionId, discussion.Title, discussion.CreatorID, discussion.CourseId);

                return(new { Res = true });
            }
            catch (Exception e)
            {
                return(new { Res = false, Error = e.Message });
            }
        }