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58 lines
1.5 KiB
58 lines
1.5 KiB
""" |
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32. Callable defaults |
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You can pass callable objects as the ``default`` parameter to a field. When |
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the object is created without an explicit value passed in, Django will call |
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the method to determine the default value. |
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This example uses ``datetime.datetime.now`` as the default for the ``pub_date`` |
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field. |
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""" |
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from django.db import models |
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from datetime import datetime |
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class Article(models.Model): |
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headline = models.CharField(max_length=100, default='Default headline') |
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pub_date = models.DateTimeField(default=datetime.now) |
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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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# No articles are in the system yet. |
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>>> Article.objects.all() |
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[] |
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# Create an Article. |
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>>> a = Article(id=None) |
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# Grab the current datetime it should be very close to the default that just |
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# got saved as a.pub_date |
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>>> now = datetime.now() |
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# Save it into the database. You have to call save() explicitly. |
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>>> a.save() |
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# Now it has an ID. Note it's a long integer, as designated by the trailing "L". |
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>>> a.id |
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1L |
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# Access database columns via Python attributes. |
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>>> a.headline |
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u'Default headline' |
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# make sure the two dates are sufficiently close |
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>>> d = now - a.pub_date |
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>>> d.seconds < 5 |
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True |
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# make sure that SafeString/SafeUnicode fields work |
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>>> from django.utils.safestring import SafeUnicode, SafeString |
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>>> a.headline = SafeUnicode(u'SafeUnicode Headline') |
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>>> a.save() |
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>>> a.headline = SafeString(u'SafeString Headline') |
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>>> a.save() |
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"""}
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