168 lines
4.9 KiB
Python
168 lines
4.9 KiB
Python
"""
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1. Bare-bones model
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This is a basic model with only two non-primary-key fields.
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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, default='Default headline')
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pub_date = meta.DateTimeField()
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API_TESTS = """
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# No articles are in the system yet.
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>>> articles.get_list()
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[]
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# Create an Article.
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>>> from datetime import datetime
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>>> a = articles.Article(id=None, headline='Area man programs in Python',
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... pub_date=datetime(2005, 7, 28))
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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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'Area man programs in Python'
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>>> a.pub_date
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datetime.datetime(2005, 7, 28, 0, 0)
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# Change values by changing the attributes, then calling save().
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>>> a.headline = 'Area woman programs in Python'
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>>> a.save()
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# get_list() displays all the articles in the database. Note that the article
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# is represented by "<Article object>", because we haven't given the Article
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# model a __repr__() method.
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>>> articles.get_list()
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[<Article object>]
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# Django provides a rich database lookup API that's entirely driven by
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# keyword arguments.
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>>> articles.get_object(id__exact=1)
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<Article object>
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>>> articles.get_object(headline__startswith='Area woman')
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<Article object>
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>>> articles.get_object(pub_date__year=2005)
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<Article object>
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# Django raises an ArticleDoesNotExist exception for get_object()
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>>> articles.get_object(id__exact=2)
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Traceback (most recent call last):
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...
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ArticleDoesNotExist: Article does not exist for {'id__exact': 2}
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# Lookup by a primary key is the most common case, so Django provides a
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# shortcut for primary-key exact lookups.
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# The following is identical to articles.get_object(id__exact=1).
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>>> articles.get_object(pk=1)
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<Article object>
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# Model instances of the same type and same ID are considered equal.
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>>> a = articles.get_object(pk=1)
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>>> b = articles.get_object(pk=1)
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>>> a == b
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True
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# You can initialize a model instance using positional arguments, which should
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# match the field order as defined in the model...
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>>> a2 = articles.Article(None, 'Second article', datetime(2005, 7, 29))
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>>> a2.save()
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>>> a2.id
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2L
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>>> a2.headline
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'Second article'
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>>> a2.pub_date
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datetime.datetime(2005, 7, 29, 0, 0)
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# ...or, you can use keyword arguments.
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>>> a3 = articles.Article(id=None, headline='Third article',
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... pub_date=datetime(2005, 7, 30))
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>>> a3.save()
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>>> a3.id
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3L
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>>> a3.headline
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'Third article'
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>>> a3.pub_date
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datetime.datetime(2005, 7, 30, 0, 0)
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# You can also mix and match position and keyword arguments, but be sure not to
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# duplicate field information.
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>>> a4 = articles.Article(None, 'Fourth article', pub_date=datetime(2005, 7, 31))
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>>> a4.save()
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>>> a4.headline
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'Fourth article'
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# Don't use invalid keyword arguments.
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>>> a5 = articles.Article(id=None, headline='Invalid', pub_date=datetime(2005, 7, 31), foo='bar')
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Traceback (most recent call last):
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...
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TypeError: 'foo' is an invalid keyword argument for this function
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# You can leave off the ID.
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>>> a5 = articles.Article(headline='Article 6', pub_date=datetime(2005, 7, 31))
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>>> a5.save()
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>>> a5.id
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5L
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>>> a5.headline
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'Article 6'
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# If you leave off a field with "default" set, Django will use the default.
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>>> a6 = articles.Article(pub_date=datetime(2005, 7, 31))
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>>> a6.save()
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>>> a6.headline
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'Default headline'
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# For DateTimeFields, Django saves as much precision (in seconds) as you
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# give it.
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>>> a7 = articles.Article(headline='Article 7', pub_date=datetime(2005, 7, 31, 12, 30))
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>>> a7.save()
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>>> articles.get_object(id__exact=7).pub_date
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datetime.datetime(2005, 7, 31, 12, 30)
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>>> a8 = articles.Article(headline='Article 8', pub_date=datetime(2005, 7, 31, 12, 30, 45))
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>>> a8.save()
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>>> articles.get_object(id__exact=8).pub_date
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datetime.datetime(2005, 7, 31, 12, 30, 45)
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>>> a8.id
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8L
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# Saving an object again shouldn't create a new object -- it just saves the old one.
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>>> a8.save()
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>>> a8.id
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8L
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>>> a8.headline = 'Updated article 8'
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>>> a8.save()
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>>> a8.id
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8L
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"""
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from django.conf import settings
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building_docs = getattr(settings, 'BUILDING_DOCS', False)
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if building_docs or settings.DATABASE_ENGINE == 'postgresql':
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API_TESTS += """
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# In PostgreSQL, microsecond-level precision is available.
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>>> a9 = articles.Article(headline='Article 9', pub_date=datetime(2005, 7, 31, 12, 30, 45, 180))
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>>> a9.save()
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>>> articles.get_object(id__exact=9).pub_date
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datetime.datetime(2005, 7, 31, 12, 30, 45, 180)
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"""
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if building_docs or settings.DATABASE_ENGINE == 'mysql':
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API_TESTS += """
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# In MySQL, microsecond-level precision isn't available. You'll lose
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# microsecond-level precision once the data is saved.
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>>> a9 = articles.Article(headline='Article 9', pub_date=datetime(2005, 7, 31, 12, 30, 45, 180))
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>>> a9.save()
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>>> articles.get_object(id__exact=9).pub_date
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datetime.datetime(2005, 7, 31, 12, 30, 45)
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"""
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