CODEWITHSUNDEEP
pythondjango
Samuel Dauzon
Samuel Dauzon

Reputation: 11334

Django models update calculated field according another field

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.

Upvotes: 1

Views: 1930

Answers (1)

Iain Shelvington
Iain Shelvington

Reputation: 32294

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)

Upvotes: 5

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