auto_now_add=True column creates IntegrityError if model is saved by specifying an id

[gtorok@…]

To reproduce, create a new model which has an auto_now_add=True field and specify the id. When calling save() the IntegrityError is raised:

# Order has this field: created_at = models.DateTimeField(auto_now_add=True, null=False)
o = models.Order(id=1, name="abc")
o.save()
IntegrityError: null value in column "created_at" violates not-null constraint

[anonymous]

Here is the code section, correctly formatted:

# Order has this field: created_at = models.DateTimeField?(auto_now_add=True, null=False) 
o = models.Order(id=1, name="abc") 
o.save() 
IntegrityError: null value in column "created_at" violates not-null constraint

[anonymous]

Also, I should add that the Order with id=1 already existed in the db (with a valid created_at date) at the time it was saved again. So it's the second save() that causes the problem.

[Anssi Kääriäinen]

There isn't any bug if this happens only when there is already an object with the same PK in the database. Because now you are not doing an add, you are doing an update. I think it works as specified, although I can see that this might be a bit confusing. The key here is that the id field's value identifies the object, so from Django's point of view you are really saving the same object to the DB, not adding a new one.