django - Django ManyToMany 字段的 set() 操作是否清除现有关系？

Question

Django ORM 操作中下面2种情况有区别吗？会有任何性能提升等吗？

obj.manytomanyfield.clear()
obj.manytomanyfield.add(1,2,3,4,5)

和

obj.manytomanyfield.set([1,2,3,4,5])

Answer 1

来自文档，set()-Django doc

This method accepts a clear argument to control how to perform the operation. If False (the default), the elements missing from the new set are removed using remove() and only the new ones are added. If clear=True, the clear() method is called instead and the whole set is added at once.

这意味着，

obj.manytomanyfield.clear()
obj.manytomanyfield.add(1,2,3,4,5)

等于

obj.manytomanyfield.set([1,2,3,4,5], <b>clear=True</b>)