Django多对多模型

Django多对多模型

models.py

from django.db import modelsclass Blog(models.Model): name = models.CharField(max_length=100) tagline = models.TextField()class Author(models.Model): name = models.CharField(max_length=50) email = models.EmailField()class Entry(models.Model): blog = models.ForeignKey(Blog) headline = models.CharField(max_length=255) body_text = models.TextField() pub_date = models.DateField() mod_date = models.DateField() authors = models.ManyToManyField(Author) n_comments = models.IntegerField() n_pingbacks = models.IntegerField() rating = models.IntegerField()views.py

##############多对多###############正向操作# obj = models.Entry.objects.get(id=1)# print(obj,obj.headline,obj.authors)# print(obj.authors.all())# author1 = models.Author.objects.filter(id__gt=2)# author1 = models.Author.objects.filter(id=2)# print(author1)# obj.authors.add(*author1)#反向操作 _set关键字# author1 = models.Author.objects.get(id=2)# author1.entry_set.add(*models.Entry.objects.filter(id=1))# print(author1,author1.name,entry1)#_set 关联表相关操作# author1 = models.Author.objects.get(id=1)# author1.entry_set.add(*models.Entry.objects.filter(id=1))#删除关联表信息# author1.entry_set.remove(*models.Entry.objects.filter(id=1))#修改关联表 清空所有再增加数据 默认clear=False 如果数据存在 不做修改# author1.entry_set.set(models.Entry.objects.filter(id__gt=1))# author1.entry_set.set(models.Entry.objects.filter(id=2))#默认clear=True 则清楚所有 再添加# author1.entry_set.set(models.Entry.objects.filter(id=2),clear=True)#delete() 慎用 删除关联表中与author1 id=1相关的 并且 删除另外一个字段关联的表entry的数据# author1.entry_set.all().delete()#create , get_or_create ,update_or_create# author1.entry_set.get_or_create(body_text='h33333')

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