Django ManyToMany 添加、刪除關聯、查詢

多對多表之間關系表

models.py文件代碼

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 "author_name:{}".format(self.name)

查詢與操作方法代碼

import os

if __name__ == '__main__':
    #加載Django項目的配置信息
    os.environ.setdefault("DJANGO_SETTINGS_MODULE","testinclude.settings")
    #導入Django,並啟動Django項目
    import django
    django.setup()

    from ormtest.models import Author,Book
   
    author = models.Author.objects.get(name="小白")
    author_books = author.book.all() # 獲取小白寫的所有書

    author.book.create(title="zabbix從入門到精通",publisher_id=3) # 為小白創建書，指定相應的出版社，並自動創建關聯記錄

    book = models.Book.objects.get(title="網絡基礎原理")
    author.book.add(book) #add:為小白作者，添加一本書(網絡基礎原理)

    book = models.Book.objects.get(title="網絡基礎原理")
    author.book.remove(book) #刪除一本書<網絡基礎原理>
    author.book.remove(4) #刪除id為4的書,並去除關聯
    
    author.book.clear() # 清空小白的書

　　book.author_set.all() #反向查詢，獲取書的所有作者