QuerySet - filter through related objects

[fgrzadkowski]

Lets say we have models like:

class A(models.Model):
    pass

class B(models.Model):
    t = models.CharField(max_length=100)
    a = models.ForeignKey('A')

I've found out, that the following query is working:

A.objects.filter(b__t='1').filter(b__t='2')

which returns those As that have at least one B with t='1' AND at
least one B with t='2'. The underlying query looks like this:

SELECT "search_test_a"."id"
FROM "search_test_a"
INNER JOIN "search_test_b" ON ("search_test_a"."id" = "search_test_b"."a_id")
INNER JOIN "search_test_b" T3 ON ("search_test_a"."id" = T3."a_id")
WHERE ("search_test_b"."t" = E'1'  AND T3."t" = E'2' ) LIMIT 21

So we have two thigns which are not documented (or I can't find it):

• possibility to filter like above
• if we set related_name="bs" in B for field a, then it affect not only foreignkey manager in A, but also filter function ( .filter(bs__t='1' )

Or maybe its all not official features? But if not then it should be, because it's very useful :)