Python之Django--ORM连表操作

一对多

class UserType(models.Model):
caption = models.CharField(max_length=32)

class UserInfo(models.Model):
user_type = models.ForeignKey(UserType)# user_type对象中封装id,caption
username = models.CharField(max_length=32)
age = models.IntegerField()

增：

1.外键id添加

models.UserInfo.objects.create(username='xs',age=19,user_type_id=1)

2.直接添加外键的对象

obj = models.UserType(caption='haha')
obj.save()
models.UserInfo.objects.create(username='xs',age=18,user_type=obj)

查：

　　正向查询：根据userinfo查usertype

result = models.UserInfo.objects.filter(user_type__caption='CTO')
for item in result:
print item.username,item.age,item.user_type.caption

　　反向查询：根据usertype查userinfo

result = models.UserType.objects.get(id=1)
print '-->0',result
print '-->1',result.userinfo_set
print '-->2',result.userinfo_set.all()
print '-->3',result.userinfo_set.filter(username='xs') #用字段条件查询
print '-->4',models.UserInfo.objects.filter(user_type=result) #用对象条件查询

user_type_obj = models.UserType.objects.get(userinfo__username='xs')
print '-->0',user_type_obj.caption
print '-->1',user_type_obj.userinfo_set.all().count()
return HttpResponse('ok')

多对多

class Host(models.Model):
hostname = models.CharField(max_length=32)
port = models.IntegerField()

class HostAdmin(models.Model):
username = models.CharField(max_length=32)
email = models.CharField(max_length=32)
host = models.ManyToManyField(Host)

增：

　　正向增：

admin_obj = models.HostAdmin.objects.get(username='xs')
host_list = models.Host.objects.filter(id__lt=3)
admin_obj.host.add(*host_list)

　　反向增：

host_obj = models.Host.objects.get(id=3)
admin_list= models.HostAdmin.objects.filter(id__gt=1)
host_obj.hostadmin_set.add(*admin_list)

区别总结：区别在于正向查拥有自己创建好的host句柄，可以直接使用add方法添加，而反向查没有，所以要使用django为我们提供的set句柄。

#正向增加

admin_obj = models.HostAdmin.objects.get(username='xs')
host_list = models.Host.objects.filter(id__lt=3)
admin_obj.host.add(*host_list)

#反向添加

host_obj = model.Host.objects.get(id=3)
admin_list = models.HostAdmin.objects.filter(id__gt=1)
host_obj.hostadmin_set.add(*admin_list)

查:

#正向查
admin_obj = models.HostAdmin.objects.get(username='xs')
print admin_obj.host.all()
#反向查
host_obj = models.Host.objects.get(id=3)
print host_obj.hostadmin_set.all()

#增
#models.HostRelation.objects.create(host_id=1,admin_id=1)
#查
relationList = models.HostRelation.objects.all()
for item in relationList:
print item.host.hostname
print item.admin.username

自定义多对多表操作