django/tests/testapp/models/many_to_one.py

98 lines
2.8 KiB
Python
Raw Normal View History

"""
4. Many-to-one relationships
To define a many-to-one relationship, use ``ForeignKey()`` .
"""
from django.core import meta
class Reporter(meta.Model):
first_name = meta.CharField(maxlength=30)
last_name = meta.CharField(maxlength=30)
def __repr__(self):
return "%s %s" % (self.first_name, self.last_name)
class Article(meta.Model):
headline = meta.CharField(maxlength=100)
pub_date = meta.DateField()
reporter = meta.ForeignKey(Reporter)
def __repr__(self):
return self.headline
API_TESTS = """
# Create a Reporter.
>>> r = reporters.Reporter(first_name='John', last_name='Smith')
>>> r.save()
# Create an Article.
>>> from datetime import datetime
>>> a = articles.Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter=r)
>>> a.save()
>>> a.reporter_id
1
>>> a.get_reporter()
John Smith
# Article objects have access to their related Reporter objects.
>>> r = a.get_reporter()
>>> r.first_name, r.last_name
('John', 'Smith')
# Create an Article via the Reporter object.
>>> new_article = r.add_article(headline="John's second story", pub_date=datetime(2005, 7, 29))
>>> new_article
John's second story
>>> new_article.reporter_id
1
# Reporter objects have access to their related Article objects.
>>> r.get_article_list(order_by=['pub_date'])
[This is a test, John's second story]
>>> r.get_article(headline__startswith='This')
This is a test
>>> r.get_article_count()
2
# The API automatically follows relationships as far as you need.
# Use double underscores to separate relationships.
# This works as many levels deep as you want. There's no limit.
# Find all Articles for any Reporter whose first name is "John".
>>> articles.get_list(reporter__first_name__exact='John', order_by=['pub_date'])
[This is a test, John's second story]
# Find all Articles for the Reporter whose ID is 1.
>>> articles.get_list(reporter__id__exact=1, order_by=['pub_date'])
[This is a test, John's second story]
# Note you need two underscores between "reporter" and "id" -- not one.
>>> articles.get_list(reporter_id__exact=1)
Traceback (most recent call last):
...
TypeError: got unexpected keyword argument 'reporter_id__exact'
# "pk" shortcut syntax works in a related context, too.
>>> articles.get_list(reporter__pk=1, order_by=['pub_date'])
[This is a test, John's second story]
# You can also instantiate an Article by passing
# the Reporter's ID instead of a Reporter object.
>>> a3 = articles.Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter_id=r.id)
>>> a3.save()
>>> a3.reporter_id
1
>>> a3.get_reporter()
John Smith
# Similarly, the reporter ID can be a string.
>>> a4 = articles.Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter_id="1")
>>> a4.save()
>>> a4.get_reporter()
John Smith
"""