Queries using prefetch_relations are not lazy

[fgmacedo]

Hi, I've found that prefetch_relations evaluates all queries, not alowing cascading further filters.

So, the following query will retrive all notifications from DB:

Notification.objects.active().filter(nf_type='my_type')

I think that we should remove the implicit call to prefetch_relations from the NotificationQueryset, and add a new queryset method like prefetch, to be explicit called when the context needs it. With a note that prefetch is not lazy.

The above example can be fixed using:

pretetch_relations(Notification.objects.filter(nf_type='badge_awarded'))

Or if we implement pretetch as a isolated queryset method:

Notification.objects.filter(nf_type='badge_awarded').prefetch()

What do you think?

[v1k45]

prefetch as a queryset method looks more clean to me. Are you already working on it?

[fgmacedo]

Ok. Not yet. But it's something that I will need, so expect it to the next few days.