sqlalchemy.exc.InvalidRequestError：无法附加实例另一个具有密钥的实例已存在于此会话中

Here I have a mistake that I can't find the solution. Please excuse me for the quality of the code, I didn't start classes until 6 months ago. I've tried to detach category objects with expunge but once it's added it doesn't work.I was thinking when detaching the object with expunge it will work. and I can't find a solution :( . I pasted as much code as I could so you could see Here I have a mistake that I can't find the sol