Django之多对多查询与操作方法详解

Django之多对多查询与操作方法详解

多对多表之间关系表

models.py文件代码

from django.db import models

# Create your models here.

class Publisher(models.Model):

id = models.AutoField(primary_key=True)

name = models.CharField(max_length=64,null=False,unique=True)

def __str__(self):

return "publisher_name:{}".format(self.name)

class Book(models.Model):

id = models.AutoField(primary_key=True)

title = models.CharField(max_length=128,null=False)

publisher = models.ForeignKey(to=Publisher,related_name="books")

def __str__(self):

return "book_title:{}".format(self.title)

class Author(models.Model):

id = models.AutoField(primary_key=True)

name = models.CharField(max_length=16,null=False)

book = models.ManyToManyField(to="Book")

def __str__(self):

return http://"author_name:{}".format(self.name)

查询与操作方法代码

import os

if __name__ == '__main__':

#加载Django项目的配置信息

os.environ.setdefault("DJANGO_SETTINGS_MODULE","testinclude.settings")

#导入Django,并启动Django项目

import django

django.setup()

from ormtest import models

#多对多查询

author_obj = models.Author.objects.get(name="小白")

print(author_obj)

author_obj_books = author_obj.book.all()

print(author_obj_books)

#首先：在book表中创建一本书，并指定相应的出版社

author_obj.book.create(title="zabbix从入门到精通",publisher_id=3)

book_obj = models.Book.objects.get(title="网络基础原理")

author_obj.book.add(book_obj)

book_obj = models.Book.objects.get(title="网络基础原理")

author_obj.book.remove(book_obj)

author_obj.book.remove(4)

author_obj.book.clear()

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