141 lines
4.8 KiB
Python
141 lines
4.8 KiB
Python
"""
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7. The lookup API
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This demonstrates features of the database API.
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"""
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from django.core import meta
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class Article(meta.Model):
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headline = meta.CharField(maxlength=100)
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pub_date = meta.DateTimeField()
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class META:
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ordering = ('-pub_date', 'headline')
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def __repr__(self):
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return self.headline
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API_TESTS = """
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# Create a couple of Articles.
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>>> from datetime import datetime
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>>> a1 = articles.Article(headline='Article 1', pub_date=datetime(2005, 7, 26))
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>>> a1.save()
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>>> a2 = articles.Article(headline='Article 2', pub_date=datetime(2005, 7, 27))
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>>> a2.save()
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>>> a3 = articles.Article(headline='Article 3', pub_date=datetime(2005, 7, 27))
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>>> a3.save()
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>>> a4 = articles.Article(headline='Article 4', pub_date=datetime(2005, 7, 28))
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>>> a4.save()
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>>> a5 = articles.Article(headline='Article 5', pub_date=datetime(2005, 8, 1, 9, 0))
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>>> a5.save()
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>>> a6 = articles.Article(headline='Article 6', pub_date=datetime(2005, 8, 1, 8, 0))
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>>> a6.save()
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>>> a7 = articles.Article(headline='Article 7', pub_date=datetime(2005, 7, 27))
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>>> a7.save()
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# get_iterator() is just like get_list(), but it's a generator.
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>>> for a in articles.get_iterator():
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... print a.headline
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Article 5
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Article 6
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Article 4
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Article 2
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Article 3
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Article 7
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Article 1
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# get_iterator() takes the same lookup arguments as get_list().
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>>> for a in articles.get_iterator(headline__endswith='4'):
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... print a.headline
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Article 4
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# get_count() returns the number of objects matching search criteria.
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>>> articles.get_count()
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7L
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>>> articles.get_count(pub_date__exact=datetime(2005, 7, 27))
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3L
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>>> articles.get_count(headline__startswith='Blah blah')
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0L
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# get_in_bulk() takes a list of IDs and returns a dictionary mapping IDs
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# to objects.
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>>> articles.get_in_bulk([1, 2])
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{1: Article 1, 2: Article 2}
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>>> articles.get_in_bulk([3])
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{3: Article 3}
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>>> articles.get_in_bulk([1000])
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{}
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# get_values() is just like get_list(), except it returns a list of
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# dictionaries instead of object instances -- and you can specify which fields
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# you want to retrieve.
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>>> articles.get_values(fields=['headline'])
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[{'headline': 'Article 5'}, {'headline': 'Article 6'}, {'headline': 'Article 4'}, {'headline': 'Article 2'}, {'headline': 'Article 3'}, {'headline': 'Article 7'}, {'headline': 'Article 1'}]
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>>> articles.get_values(pub_date__exact=datetime(2005, 7, 27), fields=['id'])
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[{'id': 2}, {'id': 3}, {'id': 7}]
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>>> articles.get_values(fields=['id', 'headline']) == [{'id': 5, 'headline': 'Article 5'}, {'id': 6, 'headline': 'Article 6'}, {'id': 4, 'headline': 'Article 4'}, {'id': 2, 'headline': 'Article 2'}, {'id': 3, 'headline': 'Article 3'}, {'id': 7, 'headline': 'Article 7'}, {'id': 1, 'headline': 'Article 1'}]
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True
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# get_values_iterator() is just like get_values(), but it's a generator.
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>>> for d in articles.get_values_iterator(fields=['id', 'headline']):
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... i = d.items()
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... i.sort()
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... i
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[('headline', 'Article 5'), ('id', 5)]
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[('headline', 'Article 6'), ('id', 6)]
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[('headline', 'Article 4'), ('id', 4)]
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[('headline', 'Article 2'), ('id', 2)]
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[('headline', 'Article 3'), ('id', 3)]
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[('headline', 'Article 7'), ('id', 7)]
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[('headline', 'Article 1'), ('id', 1)]
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# Every DateField and DateTimeField creates get_next_by_FOO() and
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# get_previous_by_FOO() methods.
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# In the case of identical date values, these methods will use the ID as a
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# fallback check. This guarantees that no records are skipped or duplicated.
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>>> a1.get_next_by_pub_date()
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Article 2
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>>> a2.get_next_by_pub_date()
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Article 3
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>>> a3.get_next_by_pub_date()
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Article 7
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>>> a4.get_next_by_pub_date()
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Article 6
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>>> a5.get_next_by_pub_date()
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Traceback (most recent call last):
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...
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ArticleDoesNotExist: Article does not exist for ...
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>>> a6.get_next_by_pub_date()
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Article 5
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>>> a7.get_next_by_pub_date()
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Article 4
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>>> a7.get_previous_by_pub_date()
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Article 3
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>>> a6.get_previous_by_pub_date()
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Article 4
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>>> a5.get_previous_by_pub_date()
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Article 6
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>>> a4.get_previous_by_pub_date()
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Article 7
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>>> a3.get_previous_by_pub_date()
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Article 2
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>>> a2.get_previous_by_pub_date()
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Article 1
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# Underscores and percent signs have special meaning in the underlying
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# database library, but Django handles the quoting of them automatically.
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>>> a8 = articles.Article(headline='Article_ with underscore', pub_date=datetime(2005, 11, 20))
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>>> a8.save()
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>>> articles.get_list(headline__startswith='Article')
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[Article_ with underscore, Article 5, Article 6, Article 4, Article 2, Article 3, Article 7, Article 1]
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>>> articles.get_list(headline__startswith='Article_')
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[Article_ with underscore]
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>>> a9 = articles.Article(headline='Article% with percent sign', pub_date=datetime(2005, 11, 21))
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>>> a9.save()
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>>> articles.get_list(headline__startswith='Article')
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[Article% with percent sign, Article_ with underscore, Article 5, Article 6, Article 4, Article 2, Article 3, Article 7, Article 1]
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>>> articles.get_list(headline__startswith='Article%')
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[Article% with percent sign]
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"""
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