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9c52d56f6f
This is a big internal change, but mostly backwards compatible with existing code. Also adds a couple of new features. Fixed #245, #1050, #1656, #1801, #2076, #2091, #2150, #2253, #2306, #2400, #2430, #2482, #2496, #2676, #2737, #2874, #2902, #2939, #3037, #3141, #3288, #3440, #3592, #3739, #4088, #4260, #4289, #4306, #4358, #4464, #4510, #4858, #5012, #5020, #5261, #5295, #5321, #5324, #5325, #5555, #5707, #5796, #5817, #5987, #6018, #6074, #6088, #6154, #6177, #6180, #6203, #6658 git-svn-id: http://code.djangoproject.com/svn/django/trunk@7477 bcc190cf-cafb-0310-a4f2-bffc1f526a37
81 lines
3.0 KiB
Python
81 lines
3.0 KiB
Python
"""
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6. Specifying ordering
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Specify default ordering for a model using the ``ordering`` attribute, which
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should be a list or tuple of field names. This tells Django how to order
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queryset results.
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If a field name in ``ordering`` starts with a hyphen, that field will be
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ordered in descending order. Otherwise, it'll be ordered in ascending order.
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The special-case field name ``"?"`` specifies random order.
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The ordering attribute is not required. If you leave it off, ordering will be
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undefined -- not random, just undefined.
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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(max_length=100)
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pub_date = models.DateTimeField()
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class Meta:
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ordering = ('-pub_date', 'headline')
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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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# Create a couple of Articles.
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>>> from datetime import datetime
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>>> a1 = Article(headline='Article 1', pub_date=datetime(2005, 7, 26))
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>>> a1.save()
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>>> a2 = Article(headline='Article 2', pub_date=datetime(2005, 7, 27))
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>>> a2.save()
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>>> a3 = Article(headline='Article 3', pub_date=datetime(2005, 7, 27))
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>>> a3.save()
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>>> a4 = Article(headline='Article 4', pub_date=datetime(2005, 7, 28))
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>>> a4.save()
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# By default, Article.objects.all() orders by pub_date descending, then
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# headline ascending.
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>>> Article.objects.all()
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[<Article: Article 4>, <Article: Article 2>, <Article: Article 3>, <Article: Article 1>]
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# Override ordering with order_by, which is in the same format as the ordering
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# attribute in models.
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>>> Article.objects.order_by('headline')
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[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>]
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>>> Article.objects.order_by('pub_date', '-headline')
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[<Article: Article 1>, <Article: Article 3>, <Article: Article 2>, <Article: Article 4>]
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# Only the last order_by has any effect (since they each override any previous
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# ordering).
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>>> Article.objects.order_by('id')
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[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>]
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>>> Article.objects.order_by('id').order_by('-headline')
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[<Article: Article 4>, <Article: Article 3>, <Article: Article 2>, <Article: Article 1>]
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# Use the 'stop' part of slicing notation to limit the results.
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>>> Article.objects.order_by('headline')[:2]
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[<Article: Article 1>, <Article: Article 2>]
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# Use the 'stop' and 'start' parts of slicing notation to offset the result list.
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>>> Article.objects.order_by('headline')[1:3]
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[<Article: Article 2>, <Article: Article 3>]
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# Getting a single item should work too:
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>>> Article.objects.all()[0]
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<Article: Article 4>
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# Use '?' to order randomly. (We're using [...] in the output to indicate we
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# don't know what order the output will be in.
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>>> Article.objects.order_by('?')
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[...]
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# Ordering can be reversed using the reverse() method on a queryset. This
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# allows you to extract things like "the last two items" (reverse and then
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# take the first two).
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>>> Article.objects.all().reverse()[:2]
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[<Article: Article 1>, <Article: Article 3>]
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"""}
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