Django 模型根据另一个字段更新计算字段

Question

I use Django and I want update many records of my model by using a calculation like in SQL like that:

UPDATE table SET amount = pre_tax * 1.2 WHERE amount IS NULL;

I want do that with Django ORM. I didn't find any ways to do that.

This answer Django - Update model field based on another field don't use bulk update, I need a syntax that allows updating several records.

Answer 1

You can use an F expression and .update() to update multiple records at once . The F expression allows you to reference an existing value in the row

Model.objects.filter(amount__isnull=True).update(amount=F('pre_tax') * 1.2)