Django多对多模型

models.py

from django.db import models


class 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')

总结：

 

其他：