还有一个问题，我使用
clean_deta打断点是为空，用data才有数据，这是为啥
所以我用了data，返回的fav_type是str，当到删除收藏的时候 给收藏数减1的if段，就要跟字符串的数字做判断

 if fav_type == 1:
                    course = Course.objects.get(id=fav_id)
                    course.fav_nums -= 1
                    course.save()
                elif fav_type == 2:
                    course_org = CourseOrg.objects.get(id=fav_id)
                    course_org.fav_nums -= 1
                    course_org.save()
                elif fav_type == 3:
                    teacher = Teacher.objects.get(id=fav_id)
                    teacher.fav_nums -= 1
                    teacher.save()