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Code Issues 32 Releases Wiki Activity

Fixed #7210 -- Added F() expressions to query language. See the documentation for details on usage.

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Many thanks to:
    * Nicolas Lara, who worked on this feature during the 2008 Google Summer of Code.
    * Alex Gaynor for his help debugging and fixing a number of issues.
    * Malcolm Tredinnick for his invaluable review notes.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9792 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Russell Keith-Magee
2009-01-29 10:46:36 +00:00
parent 08dd4176ed
commit cf37e4624a
16 changed files with 586 additions and 48 deletions
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17
tests/regressiontests/aggregation_regress/models.py
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@@ -50,7 +50,7 @@ class Store(models.Model):
#Extra does not play well with values. Modify the tests if/when this is fixed.
__test__ = {'API_TESTS': """
>>> from django.core import management
>>> from django.db.models import get_app
>>> from django.db.models import get_app, F
# Reset the database representation of this app.
# This will return the database to a clean initial state.
@@ -164,6 +164,21 @@ FieldError: Cannot resolve keyword 'foo' into field. Choices are: authors, id, i
>>> len(Book.objects.annotate(num_authors=Count('authors')).exclude(num_authors__lt=2).filter(num_authors__lt=3))
2
# Aggregates can be used with F() expressions
# ... where the F() is pushed into the HAVING clause
>>> Publisher.objects.annotate(num_books=Count('book')).filter(num_books__lt=F('num_awards')/2).values('name','num_books','num_awards')
[{'num_books': 2, 'name': u'Prentice Hall', 'num_awards': 7}, {'num_books': 1, 'name': u'Morgan Kaufmann', 'num_awards': 9}]
>>> Publisher.objects.annotate(num_books=Count('book')).exclude(num_books__lt=F('num_awards')/2).values('name','num_books','num_awards')
[{'num_books': 2, 'name': u'Apress', 'num_awards': 3}, {'num_books': 1, 'name': u'Sams', 'num_awards': 1}, {'num_books': 0, 'name': u"Jonno's House of Books", 'num_awards': 0}]
# ... and where the F() references an aggregate
>>> Publisher.objects.annotate(num_books=Count('book')).filter(num_awards__gt=2*F('num_books')).values('name','num_books','num_awards')
[{'num_books': 2, 'name': u'Prentice Hall', 'num_awards': 7}, {'num_books': 1, 'name': u'Morgan Kaufmann', 'num_awards': 9}]
>>> Publisher.objects.annotate(num_books=Count('book')).exclude(num_books__lt=F('num_awards')/2).values('name','num_books','num_awards')
[{'num_books': 2, 'name': u'Apress', 'num_awards': 3}, {'num_books': 1, 'name': u'Sams', 'num_awards': 1}, {'num_books': 0, 'name': u"Jonno's House of Books", 'num_awards': 0}]
# Regression for #10089: Check handling of empty result sets with aggregates
>>> Book.objects.filter(id__in=[]).count()
0