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I have the following Django models.
class A(models.Model):
tmp = models.ForeignKey(B)
active = models.BooleanField()
class B(models.Model):
active = models.BooleanField()
archived = models.BooleanField()
Now I have the following query.
A.objects.select_related(B).filter(active=True)
Now this fetches all the objects of B. Now how can I include a filter of active=True and archived=False in the select_related clause for model B.
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Using select_related() Django offers a QuerySet method called select_related() that allows you to retrieve related objects for one-to-many relationships. This translates to a single, more complex QuerySet, but you avoid additional queries when accessing the related objects.
This is because a Django QuerySet is a lazy object. It contains all of the information it needs to populate itself from the database, but will not actually do so until the information is needed.
select_related() “follows” foreign-key relationships, selecting additional related-object data when it executes its query. prefetch_related() does a separate lookup for each relationship and does the “joining” in Python.
Django-filter is a generic, reusable application to alleviate writing some of the more mundane bits of view code. Specifically, it allows users to filter down a queryset based on a model's fields, displaying the form to let them do this.
The same as you would with any other related field, with a __ lookup..
A.objects.select_related(B).filter(active=True, tmp__active=True, tmp__archived=False)
Using select related doesn't change anything here, its purpose is about what information is returned with the results, it has no effect on filtering at all.
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