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Fixed #29081 -- Clarified comments in QuerySet.select_related() example.

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Tim Graham 2018-01-29 10:12:58 -05:00
parent c2b969e124
commit e6f0e324e2
1 changed files with 3 additions and 1 deletions
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4
docs/ref/models/querysets.txt
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@ -935,11 +935,13 @@ following models::
... then a call to ``Book.objects.select_related('author__hometown').get(id=4)`` ... then a call to ``Book.objects.select_related('author__hometown').get(id=4)``
will cache the related ``Person`` *and* the related ``City``:: will cache the related ``Person`` *and* the related ``City``::
# Hits the database with joins to the author and hometown tables.
b = Book.objects.select_related('author__hometown').get(id=4) b = Book.objects.select_related('author__hometown').get(id=4)
p = b.author # Doesn't hit the database. p = b.author # Doesn't hit the database.
c = p.hometown # Doesn't hit the database. c = p.hometown # Doesn't hit the database.
b = Book.objects.get(id=4) # No select_related() in this example. # Without select_related()...
b = Book.objects.get(id=4) # Hits the database.
p = b.author # Hits the database. p = b.author # Hits the database.
c = p.hometown # Hits the database. c = p.hometown # Hits the database.