django model 查询 笔记二 ：多对多查询

 1 # -*- coding:utf-8 -*-
 2    # 没法贴链接，参考自 CSDN：shangliuyan,好像没法贴链接，打出名字特此感谢，如有问题请留
 3 from django.db import models
 4 
 5 
 6 # 主表
 7 class Author(models.Model):
 8     first_name = models.CharField(max_length=30)
 9     last_name = models.CharField(max_length=40)
10     email = models.EmailField()
11 
12 
13 # 从表
14 class Book(models.Model):
15     title = models.CharField(max_length=200)
16     authors = models.ManyToManyField(Author)
17 
18 # 从表查主表
19 b = Book.objects.get(id=50)
20 b.authors.all()
21 b.authors.filter(first_name=‘Adam‘)
22 
23 # 主表查从表
24 a = Author.objects.get(id=1)
25 a.book_set.all()
26 
27 # 添加对象
28 a = Author.objects.get(id=1)
29 b = Book.objects.get(id=50)
30 b.authors.add(a)
31 
32 # 删除对象
33 a = Author.objects.get(id=1)  
34 b = Book.objects.get(id=50)  
35 b.authors.remove(a) 或者 b.authors.filter(id=1).delete()