Django model latest() method

问题:

I am having the following issue (BTW I think I had not had this problem the day before):

>>> rule = Rule.objects.get(user=user)
>>> rule.id
1
>>> rule = Rule.objects.get(user=user).latest('id')

AttributeError: 'Rule' object has no attribute 'latest'

Why am I getting the error?

回答1:

The get() function of the Model Manager returns an instance of the Model itself.

The latest() function you mention belongs to the QuerySet class. Calling .filter(), .all(), .exclude() etc, all return a QuerySet.

What you're likely looking for is to first filter for the specific user, then get the latest result by 'id':

rule = Rule.objects.filter(user=user).latest('id')

See here for the docs on querying models

回答2:

latest method belongs to QuerySet, not model.

Replace following line:

rule = Rule.objects.get(user=user).latest('id')

with:

rule = Rule.objects.filter(user=user).latest('id')