author | Sverre Rabbelier <srabbelier@gmail.com> |
Thu, 27 Aug 2009 20:34:43 -0700 | |
changeset 2832 | 2a0a7e081caf |
parent 109 | 620f9b141567 |
permissions | -rwxr-xr-x |
109
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Load ../../google_appengine into trunk/thirdparty/google_appengine.
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""" |
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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 the |
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results of ``get_list()`` and other similar functions. |
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|
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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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|
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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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|
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class Article(models.Model): |
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headline = models.CharField(maxlength=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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|
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def __str__(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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# 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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|
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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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|
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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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"""} |