保存ModelForm错误（无法创建User_Message，因为数据未验证）

I came across a thread that seemed like it might be related at djangocode but it didn't really help. I'm trying to save a modelform and it's throwing an exception. I think that it might be related to referring to the same foreign key twice in my model. It might also have to do with the definition of unique=True in one of the foreign key fields. I don't knowI came across a thread that seemed like it migh