Django Left Outer Join

First of all, there is no a way (atm Django 1.9.7) to have a representation with Django’s ORM of the raw query you posted, exactly as you want; however, you can get the same desired result with something like:

>>> Topic.objects.annotate(
        f=Case(
            When(
                record__user=johnny, 
                then=F('record__value')
            ), 
            output_field=IntegerField()
        )
    ).order_by(
        'id', 'name', 'f'
    ).distinct(
        'id', 'name'
    ).values_list(
        'name', 'f'
    )
>>> [(u'A', 1), (u'B', None), (u'C', 3)]

>>> Topic.objects.annotate(f=Case(When(record__user=may, then=F('record__value')), output_field=IntegerField())).order_by('id', 'name', 'f').distinct('id', 'name').values_list('name', 'f')
>>> [(u'A', 4), (u'B', 5), (u'C', 6)]

Here the SQL generated for the first query:

>>> print Topic.objects.annotate(f=Case(When(record__user=johnny, then=F('record__value')), output_field=IntegerField())).order_by('id', 'name', 'f').distinct('id', 'name').values_list('name', 'f').query

>>> SELECT DISTINCT ON ("payments_topic"."id", "payments_topic"."name") "payments_topic"."name", CASE WHEN "payments_record"."user_id" = 1 THEN "payments_record"."value" ELSE NULL END AS "f" FROM "payments_topic" LEFT OUTER JOIN "payments_record" ON ("payments_topic"."id" = "payments_record"."topic_id") ORDER BY "payments_topic"."id" ASC, "payments_topic"."name" ASC, "f" ASC

##Some notes

• Doesn’t hesitate to use raw queries, specially when the performance is the most important thing. Moreover, sometimes it is a must since you can’t get the same result using Django’s ORM; in other cases you can, but once in a while having clean and understandable code is more important than the performance in this piece of code.
• distinct with positional arguments is used in this answer, which is available for PostgreSQL only, atm. In the docs you can see more about conditional expressions.