120 lines
4.3 KiB
Python
120 lines
4.3 KiB
Python
"""
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19. OR lookups
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To perform an OR lookup, or a lookup that combines ANDs and ORs,
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combine QuerySet objects using & and | operators.
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Alternatively, use positional arguments, and pass one or more expressions
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of clauses using the variable ``django.db.models.Q`` (or any object with
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a get_sql method).
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"""
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from django.db import models
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class Article(models.Model):
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headline = models.CharField(maxlength=50)
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pub_date = models.DateTimeField()
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class Meta:
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ordering = ('pub_date',)
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def __unicode__(self):
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return self.headline
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__test__ = {'API_TESTS':"""
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>>> from datetime import datetime
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>>> from django.db.models import Q
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>>> a1 = Article(headline='Hello', pub_date=datetime(2005, 11, 27))
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>>> a1.save()
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>>> a2 = Article(headline='Goodbye', pub_date=datetime(2005, 11, 28))
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>>> a2.save()
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>>> a3 = Article(headline='Hello and goodbye', pub_date=datetime(2005, 11, 29))
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>>> a3.save()
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>>> Article.objects.filter(headline__startswith='Hello') | Article.objects.filter(headline__startswith='Goodbye')
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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>>> Article.objects.filter(Q(headline__startswith='Hello') | Q(headline__startswith='Goodbye'))
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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>>> Article.objects.filter(Q(headline__startswith='Hello') & Q(headline__startswith='Goodbye'))
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[]
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# You can shorten this syntax with code like the following,
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# which is especially useful if building the query in stages:
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>>> articles = Article.objects.all()
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>>> articles.filter(headline__startswith='Hello') & articles.filter(headline__startswith='Goodbye')
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[]
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>>> articles.filter(headline__startswith='Hello') & articles.filter(headline__contains='bye')
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[<Article: Hello and goodbye>]
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>>> Article.objects.filter(Q(headline__contains='bye'), headline__startswith='Hello')
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[<Article: Hello and goodbye>]
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>>> Article.objects.filter(headline__contains='Hello') | Article.objects.filter(headline__contains='bye')
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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>>> Article.objects.filter(headline__iexact='Hello') | Article.objects.filter(headline__contains='ood')
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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>>> Article.objects.filter(Q(pk=1) | Q(pk=2))
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[<Article: Hello>, <Article: Goodbye>]
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>>> Article.objects.filter(Q(pk=1) | Q(pk=2) | Q(pk=3))
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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# You could also use "in" to accomplish the same as above.
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>>> Article.objects.filter(pk__in=[1,2,3])
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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>>> Article.objects.filter(pk__in=[1,2,3,4])
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[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
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# Passing "in" an empty list returns no results ...
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>>> Article.objects.filter(pk__in=[])
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[]
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# ... but can return results if we OR it with another query.
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>>> Article.objects.filter(Q(pk__in=[]) | Q(headline__icontains='goodbye'))
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[<Article: Goodbye>, <Article: Hello and goodbye>]
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# Q arg objects are ANDed
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>>> Article.objects.filter(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
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[<Article: Hello and goodbye>]
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# Q arg AND order is irrelevant
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>>> Article.objects.filter(Q(headline__contains='bye'), headline__startswith='Hello')
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[<Article: Hello and goodbye>]
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# Try some arg queries with operations other than get_list
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>>> Article.objects.get(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
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<Article: Hello and goodbye>
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>>> Article.objects.filter(Q(headline__startswith='Hello') | Q(headline__contains='bye')).count()
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3
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>>> list(Article.objects.filter(Q(headline__startswith='Hello'), Q(headline__contains='bye')).values())
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[{'headline': u'Hello and goodbye', 'pub_date': datetime.datetime(2005, 11, 29, 0, 0), 'id': 3}]
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>>> Article.objects.filter(Q(headline__startswith='Hello')).in_bulk([1,2])
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{1: <Article: Hello>}
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# Demonstrating exclude with a Q object
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>>> Article.objects.exclude(Q(headline__startswith='Hello'))
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[<Article: Goodbye>]
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# The 'complex_filter' method supports framework features such as
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# 'limit_choices_to' which normally take a single dictionary of lookup arguments
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# but need to support arbitrary queries via Q objects too.
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>>> Article.objects.complex_filter({'pk': 1})
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[<Article: Hello>]
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>>> Article.objects.complex_filter(Q(pk=1) | Q(pk=2))
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[<Article: Hello>, <Article: Goodbye>]
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"""}
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