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136 lines
4.9 KiB
136 lines
4.9 KiB
""" |
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19. OR lookups |
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To perform an OR lookup, or a lookup that combines ANDs and ORs, combine |
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``QuerySet`` objects using ``&`` and ``|`` operators. |
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Alternatively, use positional arguments, and pass one or more expressions of |
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clauses using the variable ``django.db.models.Q`` (or any object with an |
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``add_to_query`` method). |
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""" |
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# Python 2.3 doesn't have sorted() |
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try: |
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sorted |
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except NameError: |
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from django.utils.itercompat import sorted |
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from django.db import models |
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class Article(models.Model): |
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headline = models.CharField(max_length=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)) |
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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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# Q objects can be negated |
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>>> Article.objects.filter(Q(pk=1) | ~Q(pk=2)) |
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[<Article: Hello>, <Article: Hello and goodbye>] |
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>>> Article.objects.filter(~Q(pk=1) & ~Q(pk=2)) |
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[<Article: Hello and goodbye>] |
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# This allows for more complex queries than filter() and exclude() alone would |
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# allow |
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>>> Article.objects.filter(Q(pk=1) & (~Q(pk=2) | Q(pk=3))) |
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[<Article: Hello>] |
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# Try some arg queries with operations other than filter. |
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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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>>> dicts = list(Article.objects.filter(Q(headline__startswith='Hello'), Q(headline__contains='bye')).values()) |
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>>> [sorted(d.items()) for d in dicts] |
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[[('headline', u'Hello and goodbye'), ('id', 3), ('pub_date', datetime.datetime(2005, 11, 29, 0, 0))]] |
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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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