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from django.db import models
class Publisher(models.Model):
name = models.CharField(max_length=100)
class Author(models.Model):
name = models.CharField(max_length=100)
class Book(models.Model):
name = models.CharField(max_length=100)
authors = models.ManyToManyField(Author, related_name='books')
publisher = models.ForeignKey(Publisher, related_name='books')
__test__ = {'one':"""
#
# RelatedManager
#
# First create a Publisher.
>>> p = Publisher.objects.create(name='Acme Publishing')
# Create a book through the publisher.
>>> book, created = p.books.get_or_create(name='The Book of Ed & Fred')
>>> created
True
# The publisher should have one book.
>>> p.books.count()
1
# Try get_or_create again, this time nothing should be created.
>>> book, created = p.books.get_or_create(name='The Book of Ed & Fred')
>>> created
False
# And the publisher should still have one book.
>>> p.books.count()
1
#
# ManyRelatedManager
#
# Add an author to the book.
>>> ed, created = book.authors.get_or_create(name='Ed')
>>> created
True
# Book should have one author.
>>> book.authors.count()
1
# Try get_or_create again, this time nothing should be created.
>>> ed, created = book.authors.get_or_create(name='Ed')
>>> created
False
# And the book should still have one author.
>>> book.authors.count()
1
# Add a second author to the book.
>>> fred, created = book.authors.get_or_create(name='Fred')
>>> created
True
# The book should have two authors now.
>>> book.authors.count()
2
# Create an Author not tied to any books.
>>> Author.objects.create(name='Ted')
<Author: Author object>
# There should be three Authors in total. The book object should have two.
>>> Author.objects.count()
3
>>> book.authors.count()
2
# Try creating a book through an author.
>>> ed.books.get_or_create(name="Ed's Recipies", publisher=p)
(<Book: Book object>, True)
# Now Ed has two Books, Fred just one.
>>> ed.books.count()
2
>>> fred.books.count()
1
"""}
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