import datetime import pickle from decimal import Decimal from operator import attrgetter from django.core.exceptions import FieldError from django.db.models import Count, Max, Avg, Sum, StdDev, Variance, F, Q from django.test import TestCase, Approximate, skipUnlessDBFeature from models import Author, Book, Publisher, Clues, Entries, HardbackBook class AggregationTests(TestCase): def assertObjectAttrs(self, obj, **kwargs): for attr, value in kwargs.iteritems(): self.assertEqual(getattr(obj, attr), value) def test_aggregates_in_where_clause(self): """ Regression test for #12822: DatabaseError: aggregates not allowed in WHERE clause Tests that the subselect works and returns results equivalent to a query with the IDs listed. Before the corresponding fix for this bug, this test passed in 1.1 and failed in 1.2-beta (trunk). """ qs = Book.objects.values('contact').annotate(Max('id')) qs = qs.order_by('contact').values_list('id__max', flat=True) # don't do anything with the queryset (qs) before including it as a # subquery books = Book.objects.order_by('id') qs1 = books.filter(id__in=qs) qs2 = books.filter(id__in=list(qs)) self.assertEqual(list(qs1), list(qs2)) def test_aggregates_in_where_clause_pre_eval(self): """ Regression test for #12822: DatabaseError: aggregates not allowed in WHERE clause Same as the above test, but evaluates the queryset for the subquery before it's used as a subquery. Before the corresponding fix for this bug, this test failed in both 1.1 and 1.2-beta (trunk). """ qs = Book.objects.values('contact').annotate(Max('id')) qs = qs.order_by('contact').values_list('id__max', flat=True) # force the queryset (qs) for the subquery to be evaluated in its # current state list(qs) books = Book.objects.order_by('id') qs1 = books.filter(id__in=qs) qs2 = books.filter(id__in=list(qs)) self.assertEqual(list(qs1), list(qs2)) @skipUnlessDBFeature('supports_subqueries_in_group_by') def test_annotate_with_extra(self): """ Regression test for #11916: Extra params + aggregation creates incorrect SQL. """ #oracle doesn't support subqueries in group by clause shortest_book_sql = """ SELECT name FROM aggregation_regress_book b WHERE b.publisher_id = aggregation_regress_publisher.id ORDER BY b.pages LIMIT 1 """ # tests that this query does not raise a DatabaseError due to the full # subselect being (erroneously) added to the GROUP BY parameters qs = Publisher.objects.extra(select={ 'name_of_shortest_book': shortest_book_sql, }).annotate(total_books=Count('book')) # force execution of the query list(qs) def test_aggregate(self): # Ordering requests are ignored self.assertEqual( Author.objects.order_by("name").aggregate(Avg("age")), {"age__avg": Approximate(37.444, places=1)} ) # Implicit ordering is also ignored self.assertEqual( Book.objects.aggregate(Sum("pages")), {"pages__sum": 3703}, ) # Baseline results self.assertEqual( Book.objects.aggregate(Sum('pages'), Avg('pages')), {'pages__sum': 3703, 'pages__avg': Approximate(617.166, places=2)} ) # Empty values query doesn't affect grouping or results self.assertEqual( Book.objects.values().aggregate(Sum('pages'), Avg('pages')), {'pages__sum': 3703, 'pages__avg': Approximate(617.166, places=2)} ) # Aggregate overrides extra selected column self.assertEqual( Book.objects.extra(select={'price_per_page' : 'price / pages'}).aggregate(Sum('pages')), {'pages__sum': 3703} ) def test_annotation(self): # Annotations get combined with extra select clauses obj = Book.objects.annotate(mean_auth_age=Avg("authors__age")).extra(select={"manufacture_cost": "price * .5"}).get(pk=2) self.assertObjectAttrs(obj, contact_id=3, id=2, isbn=u'067232959', mean_auth_age=45.0, name='Sams Teach Yourself Django in 24 Hours', pages=528, price=Decimal("23.09"), pubdate=datetime.date(2008, 3, 3), publisher_id=2, rating=3.0 ) # Different DB backends return different types for the extra select computation self.assertTrue(obj.manufacture_cost == 11.545 or obj.manufacture_cost == Decimal('11.545')) # Order of the annotate/extra in the query doesn't matter obj = Book.objects.extra(select={'manufacture_cost' : 'price * .5'}).annotate(mean_auth_age=Avg('authors__age')).get(pk=2) self.assertObjectAttrs(obj, contact_id=3, id=2, isbn=u'067232959', mean_auth_age=45.0, name=u'Sams Teach Yourself Django in 24 Hours', pages=528, price=Decimal("23.09"), pubdate=datetime.date(2008, 3, 3), publisher_id=2, rating=3.0 ) # Different DB backends return different types for the extra select computation self.assertTrue(obj.manufacture_cost == 11.545 or obj.manufacture_cost == Decimal('11.545')) # Values queries can be combined with annotate and extra obj = Book.objects.annotate(mean_auth_age=Avg('authors__age')).extra(select={'manufacture_cost' : 'price * .5'}).values().get(pk=2) manufacture_cost = obj['manufacture_cost'] self.assertTrue(manufacture_cost == 11.545 or manufacture_cost == Decimal('11.545')) del obj['manufacture_cost'] self.assertEqual(obj, { "contact_id": 3, "id": 2, "isbn": u"067232959", "mean_auth_age": 45.0, "name": u"Sams Teach Yourself Django in 24 Hours", "pages": 528, "price": Decimal("23.09"), "pubdate": datetime.date(2008, 3, 3), "publisher_id": 2, "rating": 3.0, }) # The order of the (empty) values, annotate and extra clauses doesn't # matter obj = Book.objects.values().annotate(mean_auth_age=Avg('authors__age')).extra(select={'manufacture_cost' : 'price * .5'}).get(pk=2) manufacture_cost = obj['manufacture_cost'] self.assertTrue(manufacture_cost == 11.545 or manufacture_cost == Decimal('11.545')) del obj['manufacture_cost'] self.assertEqual(obj, { 'contact_id': 3, 'id': 2, 'isbn': u'067232959', 'mean_auth_age': 45.0, 'name': u'Sams Teach Yourself Django in 24 Hours', 'pages': 528, 'price': Decimal("23.09"), 'pubdate': datetime.date(2008, 3, 3), 'publisher_id': 2, 'rating': 3.0 }) # If the annotation precedes the values clause, it won't be included # unless it is explicitly named obj = Book.objects.annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).values('name').get(pk=1) self.assertEqual(obj, { "name": u'The Definitive Guide to Django: Web Development Done Right', }) obj = Book.objects.annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).values('name','mean_auth_age').get(pk=1) self.assertEqual(obj, { 'mean_auth_age': 34.5, 'name': u'The Definitive Guide to Django: Web Development Done Right', }) # If an annotation isn't included in the values, it can still be used # in a filter qs = Book.objects.annotate(n_authors=Count('authors')).values('name').filter(n_authors__gt=2) self.assertQuerysetEqual( qs, [ {"name": u'Python Web Development with Django'} ], lambda b: b, ) # The annotations are added to values output if values() precedes # annotate() obj = Book.objects.values('name').annotate(mean_auth_age=Avg('authors__age')).extra(select={'price_per_page' : 'price / pages'}).get(pk=1) self.assertEqual(obj, { 'mean_auth_age': 34.5, 'name': u'The Definitive Guide to Django: Web Development Done Right', }) # Check that all of the objects are getting counted (allow_nulls) and # that values respects the amount of objects self.assertEqual( len(Author.objects.annotate(Avg('friends__age')).values()), 9 ) # Check that consecutive calls to annotate accumulate in the query qs = Book.objects.values('price').annotate(oldest=Max('authors__age')).order_by('oldest', 'price').annotate(Max('publisher__num_awards')) self.assertQuerysetEqual( qs, [ {'price': Decimal("30"), 'oldest': 35, 'publisher__num_awards__max': 3}, {'price': Decimal("29.69"), 'oldest': 37, 'publisher__num_awards__max': 7}, {'price': Decimal("23.09"), 'oldest': 45, 'publisher__num_awards__max': 1}, {'price': Decimal("75"), 'oldest': 57, 'publisher__num_awards__max': 9}, {'price': Decimal("82.8"), 'oldest': 57, 'publisher__num_awards__max': 7} ], lambda b: b, ) def test_aggrate_annotation(self): # Aggregates can be composed over annotations. # The return type is derived from the composed aggregate vals = Book.objects.all().annotate(num_authors=Count('authors__id')).aggregate(Max('pages'), Max('price'), Sum('num_authors'), Avg('num_authors')) self.assertEqual(vals, { 'num_authors__sum': 10, 'num_authors__avg': Approximate(1.666, places=2), 'pages__max': 1132, 'price__max': Decimal("82.80") }) def test_field_error(self): # Bad field requests in aggregates are caught and reported self.assertRaises( FieldError, lambda: Book.objects.all().aggregate(num_authors=Count('foo')) ) self.assertRaises( FieldError, lambda: Book.objects.all().annotate(num_authors=Count('foo')) ) self.assertRaises( FieldError, lambda: Book.objects.all().annotate(num_authors=Count('authors__id')).aggregate(Max('foo')) ) def test_more(self): # Old-style count aggregations can be mixed with new-style self.assertEqual( Book.objects.annotate(num_authors=Count('authors')).count(), 6 ) # Non-ordinal, non-computed Aggregates over annotations correctly # inherit the annotation's internal type if the annotation is ordinal # or computed vals = Book.objects.annotate(num_authors=Count('authors')).aggregate(Max('num_authors')) self.assertEqual( vals, {'num_authors__max': 3} ) vals = Publisher.objects.annotate(avg_price=Avg('book__price')).aggregate(Max('avg_price')) self.assertEqual( vals, {'avg_price__max': 75.0} ) # Aliases are quoted to protected aliases that might be reserved names vals = Book.objects.aggregate(number=Max('pages'), select=Max('pages')) self.assertEqual( vals, {'number': 1132, 'select': 1132} ) # Regression for #10064: select_related() plays nice with aggregates obj = Book.objects.select_related('publisher').annotate(num_authors=Count('authors')).values()[0] self.assertEqual(obj, { 'contact_id': 8, 'id': 5, 'isbn': u'013790395', 'name': u'Artificial Intelligence: A Modern Approach', 'num_authors': 2, 'pages': 1132, 'price': Decimal("82.8"), 'pubdate': datetime.date(1995, 1, 15), 'publisher_id': 3, 'rating': 4.0, }) # Regression for #10010: exclude on an aggregate field is correctly # negated self.assertEqual( len(Book.objects.annotate(num_authors=Count('authors'))), 6 ) self.assertEqual( len(Book.objects.annotate(num_authors=Count('authors')).filter(num_authors__gt=2)), 1 ) self.assertEqual( len(Book.objects.annotate(num_authors=Count('authors')).exclude(num_authors__gt=2)), 5 ) self.assertEqual( len(Book.objects.annotate(num_authors=Count('authors')).filter(num_authors__lt=3).exclude(num_authors__lt=2)), 2 ) self.assertEqual( len(Book.objects.annotate(num_authors=Count('authors')).exclude(num_authors__lt=2).filter(num_authors__lt=3)), 2 ) def test_aggregate_fexpr(self): # Aggregates can be used with F() expressions # ... where the F() is pushed into the HAVING clause qs = Publisher.objects.annotate(num_books=Count('book')).filter(num_books__lt=F('num_awards')/2).order_by('name').values('name','num_books','num_awards') self.assertQuerysetEqual( qs, [ {'num_books': 1, 'name': u'Morgan Kaufmann', 'num_awards': 9}, {'num_books': 2, 'name': u'Prentice Hall', 'num_awards': 7} ], lambda p: p, ) qs = Publisher.objects.annotate(num_books=Count('book')).exclude(num_books__lt=F('num_awards')/2).order_by('name').values('name','num_books','num_awards') self.assertQuerysetEqual( qs, [ {'num_books': 2, 'name': u'Apress', 'num_awards': 3}, {'num_books': 0, 'name': u"Jonno's House of Books", 'num_awards': 0}, {'num_books': 1, 'name': u'Sams', 'num_awards': 1} ], lambda p: p, ) # ... and where the F() references an aggregate qs = Publisher.objects.annotate(num_books=Count('book')).filter(num_awards__gt=2*F('num_books')).order_by('name').values('name','num_books','num_awards') self.assertQuerysetEqual( qs, [ {'num_books': 1, 'name': u'Morgan Kaufmann', 'num_awards': 9}, {'num_books': 2, 'name': u'Prentice Hall', 'num_awards': 7} ], lambda p: p, ) qs = Publisher.objects.annotate(num_books=Count('book')).exclude(num_books__lt=F('num_awards')/2).order_by('name').values('name','num_books','num_awards') self.assertQuerysetEqual( qs, [ {'num_books': 2, 'name': u'Apress', 'num_awards': 3}, {'num_books': 0, 'name': u"Jonno's House of Books", 'num_awards': 0}, {'num_books': 1, 'name': u'Sams', 'num_awards': 1} ], lambda p: p, ) def test_db_col_table(self): # Tests on fields with non-default table and column names. qs = Clues.objects.values('EntryID__Entry').annotate(Appearances=Count('EntryID'), Distinct_Clues=Count('Clue', distinct=True)) self.assertQuerysetEqual(qs, []) qs = Entries.objects.annotate(clue_count=Count('clues__ID')) self.assertQuerysetEqual(qs, []) def test_empty(self): # Regression for #10089: Check handling of empty result sets with # aggregates self.assertEqual( Book.objects.filter(id__in=[]).count(), 0 ) vals = Book.objects.filter(id__in=[]).aggregate(num_authors=Count('authors'), avg_authors=Avg('authors'), max_authors=Max('authors'), max_price=Max('price'), max_rating=Max('rating')) self.assertEqual( vals, {'max_authors': None, 'max_rating': None, 'num_authors': 0, 'avg_authors': None, 'max_price': None} ) qs = Publisher.objects.filter(pk=5).annotate(num_authors=Count('book__authors'), avg_authors=Avg('book__authors'), max_authors=Max('book__authors'), max_price=Max('book__price'), max_rating=Max('book__rating')).values() self.assertQuerysetEqual( qs, [ {'max_authors': None, 'name': u"Jonno's House of Books", 'num_awards': 0, 'max_price': None, 'num_authors': 0, 'max_rating': None, 'id': 5, 'avg_authors': None} ], lambda p: p ) def test_more_more(self): # Regression for #10113 - Fields mentioned in order_by() must be # included in the GROUP BY. This only becomes a problem when the # order_by introduces a new join. self.assertQuerysetEqual( Book.objects.annotate(num_authors=Count('authors')).order_by('publisher__name', 'name'), [ "Practical Django Projects", "The Definitive Guide to Django: Web Development Done Right", "Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp", "Artificial Intelligence: A Modern Approach", "Python Web Development with Django", "Sams Teach Yourself Django in 24 Hours", ], lambda b: b.name ) # Regression for #10127 - Empty select_related() works with annotate qs = Book.objects.filter(rating__lt=4.5).select_related().annotate(Avg('authors__age')) self.assertQuerysetEqual( qs, [ (u'Artificial Intelligence: A Modern Approach', 51.5, u'Prentice Hall', u'Peter Norvig'), (u'Practical Django Projects', 29.0, u'Apress', u'James Bennett'), (u'Python Web Development with Django', Approximate(30.333, places=2), u'Prentice Hall', u'Jeffrey Forcier'), (u'Sams Teach Yourself Django in 24 Hours', 45.0, u'Sams', u'Brad Dayley') ], lambda b: (b.name, b.authors__age__avg, b.publisher.name, b.contact.name) ) # Regression for #10132 - If the values() clause only mentioned extra # (select=) columns, those columns are used for grouping qs = Book.objects.extra(select={'pub':'publisher_id'}).values('pub').annotate(Count('id')).order_by('pub') self.assertQuerysetEqual( qs, [ {'pub': 1, 'id__count': 2}, {'pub': 2, 'id__count': 1}, {'pub': 3, 'id__count': 2}, {'pub': 4, 'id__count': 1} ], lambda b: b ) qs = Book.objects.extra(select={'pub':'publisher_id', 'foo':'pages'}).values('pub').annotate(Count('id')).order_by('pub') self.assertQuerysetEqual( qs, [ {'pub': 1, 'id__count': 2}, {'pub': 2, 'id__count': 1}, {'pub': 3, 'id__count': 2}, {'pub': 4, 'id__count': 1} ], lambda b: b ) # Regression for #10182 - Queries with aggregate calls are correctly # realiased when used in a subquery ids = Book.objects.filter(pages__gt=100).annotate(n_authors=Count('authors')).filter(n_authors__gt=2).order_by('n_authors') self.assertQuerysetEqual( Book.objects.filter(id__in=ids), [ "Python Web Development with Django", ], lambda b: b.name ) def test_duplicate_alias(self): # Regression for #11256 - duplicating a default alias raises ValueError. self.assertRaises(ValueError, Book.objects.all().annotate, Avg('authors__age'), authors__age__avg=Avg('authors__age')) def test_field_name_conflict(self): # Regression for #11256 - providing an aggregate name that conflicts with a field name on the model raises ValueError self.assertRaises(ValueError, Author.objects.annotate, age=Avg('friends__age')) def test_m2m_name_conflict(self): # Regression for #11256 - providing an aggregate name that conflicts with an m2m name on the model raises ValueError self.assertRaises(ValueError, Author.objects.annotate, friends=Count('friends')) def test_reverse_relation_name_conflict(self): # Regression for #11256 - providing an aggregate name that conflicts with a reverse-related name on the model raises ValueError self.assertRaises(ValueError, Author.objects.annotate, book_contact_set=Avg('friends__age')) def test_pickle(self): # Regression for #10197 -- Queries with aggregates can be pickled. # First check that pickling is possible at all. No crash = success qs = Book.objects.annotate(num_authors=Count('authors')) pickle.dumps(qs) # Then check that the round trip works. query = qs.query.get_compiler(qs.db).as_sql()[0] qs2 = pickle.loads(pickle.dumps(qs)) self.assertEqual( qs2.query.get_compiler(qs2.db).as_sql()[0], query, ) def test_more_more_more(self): # Regression for #10199 - Aggregate calls clone the original query so # the original query can still be used books = Book.objects.all() books.aggregate(Avg("authors__age")) self.assertQuerysetEqual( books.all(), [ u'Artificial Intelligence: A Modern Approach', u'Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp', u'Practical Django Projects', u'Python Web Development with Django', u'Sams Teach Yourself Django in 24 Hours', u'The Definitive Guide to Django: Web Development Done Right' ], lambda b: b.name ) # Regression for #10248 - Annotations work with DateQuerySets qs = Book.objects.annotate(num_authors=Count('authors')).filter(num_authors=2).dates('pubdate', 'day') self.assertQuerysetEqual( qs, [ datetime.datetime(1995, 1, 15, 0, 0), datetime.datetime(2007, 12, 6, 0, 0) ], lambda b: b ) # Regression for #10290 - extra selects with parameters can be used for # grouping. qs = Book.objects.annotate(mean_auth_age=Avg('authors__age')).extra(select={'sheets' : '(pages + %s) / %s'}, select_params=[1, 2]).order_by('sheets').values('sheets') self.assertQuerysetEqual( qs, [ 150, 175, 224, 264, 473, 566 ], lambda b: int(b["sheets"]) ) # Regression for 10425 - annotations don't get in the way of a count() # clause self.assertEqual( Book.objects.values('publisher').annotate(Count('publisher')).count(), 4 ) self.assertEqual( Book.objects.annotate(Count('publisher')).values('publisher').count(), 6 ) publishers = Publisher.objects.filter(id__in=[1, 2]) self.assertQuerysetEqual( publishers, [ "Apress", "Sams" ], lambda p: p.name ) publishers = publishers.annotate(n_books=Count("book")) self.assertEqual( publishers[0].n_books, 2 ) self.assertQuerysetEqual( publishers, [ "Apress", "Sams", ], lambda p: p.name ) books = Book.objects.filter(publisher__in=publishers) self.assertQuerysetEqual( books, [ "Practical Django Projects", "Sams Teach Yourself Django in 24 Hours", "The Definitive Guide to Django: Web Development Done Right", ], lambda b: b.name ) self.assertQuerysetEqual( publishers, [ "Apress", "Sams", ], lambda p: p.name ) # Regression for 10666 - inherited fields work with annotations and # aggregations self.assertEqual( HardbackBook.objects.aggregate(n_pages=Sum('book_ptr__pages')), {'n_pages': 2078} ) self.assertEqual( HardbackBook.objects.aggregate(n_pages=Sum('pages')), {'n_pages': 2078}, ) qs = HardbackBook.objects.annotate(n_authors=Count('book_ptr__authors')).values('name', 'n_authors') self.assertQuerysetEqual( qs, [ {'n_authors': 2, 'name': u'Artificial Intelligence: A Modern Approach'}, {'n_authors': 1, 'name': u'Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp'} ], lambda h: h ) qs = HardbackBook.objects.annotate(n_authors=Count('authors')).values('name', 'n_authors') self.assertQuerysetEqual( qs, [ {'n_authors': 2, 'name': u'Artificial Intelligence: A Modern Approach'}, {'n_authors': 1, 'name': u'Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp'} ], lambda h: h, ) # Regression for #10766 - Shouldn't be able to reference an aggregate # fields in an an aggregate() call. self.assertRaises( FieldError, lambda: Book.objects.annotate(mean_age=Avg('authors__age')).annotate(Avg('mean_age')) ) def test_empty_filter_count(self): self.assertEqual( Author.objects.filter(id__in=[]).annotate(Count("friends")).count(), 0 ) def test_empty_filter_aggregate(self): self.assertEqual( Author.objects.filter(id__in=[]).annotate(Count("friends")).aggregate(Count("pk")), {"pk__count": None} ) def test_annotate_and_join(self): self.assertEqual( Author.objects.annotate(c=Count("friends__name")).exclude(friends__name="Joe").count(), Author.objects.count() ) def test_f_expression_annotation(self): # Books with less than 200 pages per author. qs = Book.objects.values("name").annotate( n_authors=Count("authors") ).filter( pages__lt=F("n_authors") * 200 ).values_list("pk") self.assertQuerysetEqual( Book.objects.filter(pk__in=qs), [ "Python Web Development with Django" ], attrgetter("name") ) def test_values_annotate_values(self): qs = Book.objects.values("name").annotate( n_authors=Count("authors") ).values_list("pk", flat=True) self.assertEqual(list(qs), list(Book.objects.values_list("pk", flat=True))) def test_having_group_by(self): # Test that when a field occurs on the LHS of a HAVING clause that it # appears correctly in the GROUP BY clause qs = Book.objects.values_list("name").annotate( n_authors=Count("authors") ).filter( pages__gt=F("n_authors") ).values_list("name", flat=True) # Results should be the same, all Books have more pages than authors self.assertEqual( list(qs), list(Book.objects.values_list("name", flat=True)) ) def test_annotation_disjunction(self): qs = Book.objects.annotate(n_authors=Count("authors")).filter( Q(n_authors=2) | Q(name="Python Web Development with Django") ) self.assertQuerysetEqual( qs, [ "Artificial Intelligence: A Modern Approach", "Python Web Development with Django", "The Definitive Guide to Django: Web Development Done Right", ], attrgetter("name") ) qs = Book.objects.annotate(n_authors=Count("authors")).filter( Q(name="The Definitive Guide to Django: Web Development Done Right") | (Q(name="Artificial Intelligence: A Modern Approach") & Q(n_authors=3)) ) self.assertQuerysetEqual( qs, [ "The Definitive Guide to Django: Web Development Done Right", ], attrgetter("name") ) qs = Publisher.objects.annotate( rating_sum=Sum("book__rating"), book_count=Count("book") ).filter( Q(rating_sum__gt=5.5) | Q(rating_sum__isnull=True) ).order_by('pk') self.assertQuerysetEqual( qs, [ "Apress", "Prentice Hall", "Jonno's House of Books", ], attrgetter("name") ) qs = Publisher.objects.annotate( rating_sum=Sum("book__rating"), book_count=Count("book") ).filter( Q(pk__lt=F("book_count")) | Q(rating_sum=None) ).order_by("pk") self.assertQuerysetEqual( qs, [ "Apress", "Jonno's House of Books", ], attrgetter("name") ) @skipUnlessDBFeature('supports_stddev') def test_stddev(self): self.assertEqual( Book.objects.aggregate(StdDev('pages')), {'pages__stddev': Approximate(311.46, 1)} ) self.assertEqual( Book.objects.aggregate(StdDev('rating')), {'rating__stddev': Approximate(0.60, 1)} ) self.assertEqual( Book.objects.aggregate(StdDev('price')), {'price__stddev': Approximate(24.16, 2)} ) self.assertEqual( Book.objects.aggregate(StdDev('pages', sample=True)), {'pages__stddev': Approximate(341.19, 2)} ) self.assertEqual( Book.objects.aggregate(StdDev('rating', sample=True)), {'rating__stddev': Approximate(0.66, 2)} ) self.assertEqual( Book.objects.aggregate(StdDev('price', sample=True)), {'price__stddev': Approximate(26.46, 1)} ) self.assertEqual( Book.objects.aggregate(Variance('pages')), {'pages__variance': Approximate(97010.80, 1)} ) self.assertEqual( Book.objects.aggregate(Variance('rating')), {'rating__variance': Approximate(0.36, 1)} ) self.assertEqual( Book.objects.aggregate(Variance('price')), {'price__variance': Approximate(583.77, 1)} ) self.assertEqual( Book.objects.aggregate(Variance('pages', sample=True)), {'pages__variance': Approximate(116412.96, 1)} ) self.assertEqual( Book.objects.aggregate(Variance('rating', sample=True)), {'rating__variance': Approximate(0.44, 2)} ) self.assertEqual( Book.objects.aggregate(Variance('price', sample=True)), {'price__variance': Approximate(700.53, 2)} )