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"""
3. Giving models custom methods and custom module-level functions
Any method you add to a model will be available to instances.
Custom methods have the same namespace as if the model class were defined
in the dynamically-generated module. That is, methods can access
``get_list()``, ``get_object()``, ``AddManipulator``, and all other
module-level objects.
Also, custom methods have access to a few commonly-used objects for
convenience:
* The ``datetime`` module from Python's standard library.
* The ``db`` object from ``django.core.db``. This represents the database
connection, so you can do custom queries via a cursor object.
If your model method starts with "_module_", it'll be a module-level function
instead of a method. Otherwise, custom module-level functions have the same
namespace as custom methods.
"""
from django.core import meta
class Article(meta.Model):
headline = meta.CharField(maxlength=100)
pub_date = meta.DateField()
def __repr__(self):
return self.headline
def was_published_today(self):
return self.pub_date == datetime.date.today()
def get_articles_from_same_day_1(self):
return get_list(id__ne=self.id, pub_date__exact=self.pub_date)
def get_articles_from_same_day_2(self):
"""
Verbose version of get_articles_from_same_day_1, which does a custom
database query for the sake of demonstration.
"""
cursor = db.cursor()
cursor.execute("""
SELECT id, headline, pub_date
FROM custom_methods_articles
WHERE pub_date = %s
AND id != %s""", [str(self.pub_date), self.id])
# The asterisk in "Article(*row)" tells Python to expand the list into
# positional arguments to Article().
return [Article(*row) for row in cursor.fetchall()]
API_TESTS = """
# Create a couple of Articles.
>>> from datetime import date
>>> a = articles.Article(id=None, headline='Area man programs in Python', pub_date=date(2005, 7, 27))
>>> a.save()
>>> b = articles.Article(id=None, headline='Beatles reunite', pub_date=date(2005, 7, 27))
>>> b.save()
# Test the custom methods.
>>> a.was_published_today()
False
>>> a.get_articles_from_same_day_1()
[Beatles reunite]
>>> a.get_articles_from_same_day_2()
[Beatles reunite]
>>> b.get_articles_from_same_day_1()
[Area man programs in Python]
>>> b.get_articles_from_same_day_2()
[Area man programs in Python]
"""
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