django 学习-10 Django多对多关系模型

1、vim blog/models.py

class   Author(models.Model):

　　　　name = models.CharField(max_length=30)

　　　　def unicode(self):

　　　　　　　　return self.name

class Book(models.Model):

　　　　name = models.CharField(max_length=30)

　　　　authors = models.ManyToMany(Author)

　　def unicode(self):

　　　　return self.name

2、python manage.py syncdb

sqlite3  cs.db

.tables;

3、python manage.py   shell

from blog.models import Author,Book

Author.objects.create(name='a1')
Author.objects.create(name='a2')

authors = Author.objects.all()

>>> authors
[<Author: a1>, <Author: a2>]
>>> b1 = Book()
>>> b1.name='book1'
>>> b1.save()
>>> b1
<Book: book1>

a1 = Author.objects.get(name__exact='a1')

b1.authors.add(a1)

b1.authors.all()

b1.authors.remove(a1)

b1.authors.all()

b1.authors.filter(name__exact='a1')   做一个过滤

a1.book_set.add(b1)

a1.book_set.create(name='book2')

a1.book_set.all()

books = Book.objects.all()

books

a1.book_set.remove(books[0])   0是下标，表示把第一个删除

a1.book_set.all()