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git-svn-id: http://code.djangoproject.com/svn/django/trunk@549 bcc190cf-cafb-0310-a4f2-bffc1f526a37
73 lines
2.4 KiB
Python
73 lines
2.4 KiB
Python
"""
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3. Giving models custom methods and custom module-level functions
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Any method you add to a model will be available to instances.
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Custom methods have the same namespace as if the model class were defined
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in the dynamically-generated module. That is, methods can access
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``get_list()``, ``get_object()``, ``AddManipulator``, and all other
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module-level objects.
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Also, custom methods have access to a few commonly-used objects for
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convenience:
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* The ``datetime`` module from Python's standard library.
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* The ``db`` object from ``django.core.db``. This represents the database
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connection, so you can do custom queries via a cursor object.
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If your model method starts with "_module_", it'll be a module-level function
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instead of a method. Otherwise, custom module-level functions have the same
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namespace as custom methods.
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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)
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pub_date = meta.DateField()
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def __repr__(self):
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return self.headline
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def was_published_today(self):
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return self.pub_date == datetime.date.today()
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def get_articles_from_same_day_1(self):
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return get_list(id__ne=self.id, pub_date__exact=self.pub_date)
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def get_articles_from_same_day_2(self):
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"""
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Verbose version of get_articles_from_same_day_1, which does a custom
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database query for the sake of demonstration.
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"""
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cursor = db.cursor()
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cursor.execute("""
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SELECT id, headline, pub_date
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FROM custom_methods_articles
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WHERE pub_date = %s
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AND id != %s""", [str(self.pub_date), self.id])
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# The asterisk in "Article(*row)" tells Python to expand the list into
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# positional arguments to Article().
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return [Article(*row) for row in cursor.fetchall()]
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API_TESTS = """
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# Create a couple of Articles.
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>>> from datetime import date
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>>> a = articles.Article(id=None, headline='Area man programs in Python', pub_date=date(2005, 7, 27))
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>>> a.save()
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>>> b = articles.Article(id=None, headline='Beatles reunite', pub_date=date(2005, 7, 27))
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>>> b.save()
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# Test the custom methods.
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>>> a.was_published_today()
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False
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>>> a.get_articles_from_same_day_1()
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[Beatles reunite]
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>>> a.get_articles_from_same_day_2()
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[Beatles reunite]
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>>> b.get_articles_from_same_day_1()
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[Area man programs in Python]
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>>> b.get_articles_from_same_day_2()
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[Area man programs in Python]
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"""
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