Python之Django--ORM連表操做

一對多

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

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

增：

1.外鍵id添加 

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

2.直接添加外鍵的對象

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

查：

　　正向查詢：根據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

　　反向查詢：根據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') #用字段條件查詢
    print '-->4',models.UserInfo.objects.filter(user_type=result) #用對象條件查詢

    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')

多對多

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)

區別總結：區別在於正向查擁有本身建立好的host句柄，能夠直接使用add方法添加，而反向查沒有，因此要使用django爲咱們提供的set句柄。

#正向增長

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()

class Host1(models.Model):
    hostname = models.CharField(max_length=32)
    port = models.IntegerField()

class HostAdmin1(models.Model):
    username = models.CharField(max_length=32)
    email = models.CharField(max_length=32)
    host = models.ManyToManyField(Host1,through='HostRelation')

class HostRelation(models.Model):
    host =models.ForeignKey(Host1)
    admin =models.ForeignKey(HostAdmin1)

自定義多對多表建立

#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

自定義多對多表操做