ORM: Manager.latest() use pk by default

[freek.wiekmeijer@…]

This is a proposal for a small improvement in the ORM layer.

Context:
The Manager class I'm referring to is django.db.models.manager.Manager. It has a public method named latest() which retrieves the most recent record from the applicable database table. For example MyModel.objects.latest() returns a MyModel object.

Current behaviour:
You need to specify which database column to use for the latest() method. Either through a Meta class in the model ("get_latest_by" option), or as a parameter in the latest() call (i.e. MyModel.objects.latest('id')).

Suggested change:
In many situations you just want the object with the highest primary key value, which is typically the latest record inserted into the table.
Change latest() to use the models primary key by default, if no "get_latest_by" is specified in the model and no parameter is supplied to the method call.

[Jacob]

I understand the use case here, but latest is specifically designed for dates, not for primary keys. Remember: we can't guarantee that the PK is in order, or even a number. Think, for example, about a model that uses UUIDs for primary keys.

Thanks for the idea!