Django干货知识分享，ORM模型(四)

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一对一关系

使用OneToOneField，例如用户表和用户信息表

class Info(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    age = models.IntegerField()

    class Sex(models.IntegerChoices):
        男 = 1
        女 = 2

    sex = models.IntegerField(choices=Sex.choices)

新增数据

# 方式1
user_obj = User.objects.create(first_name = '小', last_name = '华')
Info.objects.create(user = user_obj, age = 20, sex = 2)

# 方式2
user_obj = User.objects.create(first_name = '小', last_name = '华')
info_dic = {'age':20, 'sex':2}
Info.objects.create(user = user_obj,**info_dic)

# 方式3
user_obj = User.objects.create(first_name = '小', last_name = '华')
info_obj = Info(user = user_obj, age = 20, sex = 2)
info_obj.save()

修改数据

# 方式1
>>> Info.objects.filter(user__last_name = '华').update(sex = 1)
(0.007) UPDATE "myapp_info" SET "sex" = 1 WHERE "myapp_info"."id" IN (SELECT U0."id" FROM "myapp_info" U0 INNER JOIN "myapp_user" U1 ON (U0."user_id" = U1."id") WHERE U1."last_name" = '华'); args=(1, '华')

# 方式2
>>> Info.objects.filter(user__last_name = '华')
>>> info_dic = {'sex': 2}
>>> Info.objects.filter(user__last_name = '华').update(**info_dic)
(0.006) UPDATE "myapp_info" SET "sex" = 2 WHERE "myapp_info"."id" IN (SELECT U0."id" FROM "myapp_info" U0 INNER JOIN "myapp_user" U1 ON (U0."user_id" = U1."id") WHERE U1."last_name" = '华'); args=(2, '华')

删除数据

>>> User.objects.get(id=3).delete()
(0.002) SELECT "myapp_user"."id", "myapp_user"."first_name", "myapp_user"."last_name" FROM "myapp_user" WHERE "myapp_user"."id" = 3 LIMIT 21; args=(3,)
(0.000) BEGIN; args=None
(0.003) DELETE FROM "myapp_info" WHERE "myapp_info"."user_id" IN (3); args=(3,)
(0.000) DELETE FROM "myapp_article" WHERE "myapp_article"."user_id" IN (3); args=(3,)
(0.000) DELETE FROM "myapp_user" WHERE "myapp_user"."id" IN (3); args=(3,)
(2, {'myapp.Info': 1, 'myapp.User': 1})

>>> Info.objects.get(id=1).delete()
(0.001) SELECT "myapp_info"."id", "myapp_info"."user_id", "myapp_info"."age", "myapp_info"."sex" FROM "myapp_info" WHERE "myapp_info"."id" = 1 LIMIT 21; args=(1,)
(0.003) DELETE FROM "myapp_info" WHERE "myapp_info"."id" IN (1); args=(1,)
(1, {'myapp.Info': 1})

查询数据

>>> user_obj = User.objects.filter(first_name='张').values('info__age', 'info__sex')
>>> print(user_obj)
(0.003) SELECT "myapp_info"."age", "myapp_info"."sex" FROM "myapp_user" LEFT OUTER JOIN "myapp_info" ON ("myapp_user"."id" = "myapp_info"."user_id") WHERE "myapp_user"."first_name" = '张' LIMIT 21; args=('张',)
<QuerySet [{'info__age': 19, 'info__sex': 2}]>

Django干货知识分享，ORM模型（三）