Python 外键 Django 模型
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Foreign Key Django Model
提问by felix001
I'm trying to create 3 models ; Person, Addressand Anniversy. The plan is to have one address and one anniversy for each person. But each address and anniversy can have multiple persons.
我正在尝试创建 3 个模型；Person，Address和Anniversy。计划是每个人有一个地址和一个纪念日。但是每个地址和纪念日可以有多个人。
So far I have the following, but I think the OneToMany(foreign key)relationships maybe the wrong way round. i.e each address can have one person but each person can have multiple addresses.
到目前为止，我有以下几点，但我认为这些OneToMany(foreign key)关系可能是错误的。即每个地址可以有一个人，但每个人可以有多个地址。
from django.db import models
class Person(models.Model):
name = models.CharField(max_length=50)
birthday = models.DateField()
def __unicode__(self):
return u'%s' % (self.name)
class Address(models.Model):
person = models.ForeignKey(Person)
address = models.CharField(max_length=150)
def __unicode__(self):
return u'%s' % (self.address)
class Anniversy(models.Model):
person = models.ForeignKey(Person)
anniversy = models.DateField()
def __unicode__(self):
return u'%s' % (self.anniversy)
采纳答案by Martijn Pieters
You create the relationships the other way around; add foreign keys to the Persontype to create a Many-to-One relationship:
您以相反的方式创建关系；向Person类型添加外键以创建多对一关系：
class Person(models.Model):
name = models.CharField(max_length=50)
birthday = models.DateField()
anniversary = models.ForeignKey(
Anniversary, on_delete=models.CASCADE)
address = models.ForeignKey(
Address, on_delete=models.CASCADE)
class Address(models.Model):
line1 = models.CharField(max_length=150)
line2 = models.CharField(max_length=150)
postalcode = models.CharField(max_length=10)
city = models.CharField(max_length=150)
country = models.CharField(max_length=150)
class Anniversary(models.Model):
date = models.DateField()
Any one person can only be connected to oneaddress and oneanniversary, but addresses and anniversaries can be referenced from multiple Personentries.
任何一个人只能连接到一个地址和一个周年纪念日，但地址和周年纪念日可以从多个Person条目中引用。
Anniversaryand Addressobjects will be given a reverse, backwards relationship too; by default it'll be called person_setbut you can configure a different name if you need to. See Following relationships "backward"in the queries documentation.
Anniversary并且Address对象也将被赋予反向的、向后的关系；默认情况下会调用它，person_set但如果需要，您可以配置不同的名称。请参阅查询文档中的以下关系“向后”。
回答by Micheal J. Roberts
I would advise, it is slightly better practise to use string model references for ForeignKeyrelationships if utilising an app based approach to seperation of logical concerns .
我建议，ForeignKey如果使用基于应用程序的方法来分离逻辑问题，那么使用字符串模型引用来建立关系会更好一些。
So, expanding on Martijn Pieters' answer:
因此，扩展 Martijn Pieters 的回答：
class Person(models.Model):
name = models.CharField(max_length=50)
birthday = models.DateField()
anniversary = models.ForeignKey(
'app_label.Anniversary', on_delete=models.CASCADE)
address = models.ForeignKey(
'app_label.Address', on_delete=models.CASCADE)
class Address(models.Model):
line1 = models.CharField(max_length=150)
line2 = models.CharField(max_length=150)
postalcode = models.CharField(max_length=10)
city = models.CharField(max_length=150)
country = models.CharField(max_length=150)
class Anniversary(models.Model):
date = models.DateField()
