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 theoperation. If False (the default), the elements missing from the newset are removed using remove() and only the new ones are added. Ifclear=True, the clear() method is called instead and the whole set isadded 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>)