52 lines
1.2 KiB
Python
52 lines
1.2 KiB
Python
"""
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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(maxlength=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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'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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"""}
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