Question

models.py

class City(models.Model):
    id = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=35)
    countrycode = models.CharField(max_length=3)
    district = models.CharField(max_length=200)
    population = models.IntegerField(default='0')

class Country(models.Model):
    code = models.CharField(primary_key=True, max_length=3)
    name = models.CharField(max_length=52)
    continent = models.CharField(max_length=50)
    region = models.CharField(max_length=26)
    surfacearea = models.FloatField()
    indepyear = models.SmallIntegerField(blank=True, null=True)
    population = models.IntegerField()
    lifeexpectancy = models.FloatField(blank=True, null=True)
    gnp = models.FloatField(blank=True, null=True)
    gnpold = models.FloatField(blank=True, null=True)
    localname = models.CharField(max_length=45)
    governmentform = models.CharField(max_length=45)
    headofstate = models.CharField(max_length=60, blank=True, null=True)
    capital = models.IntegerField(blank=True, null=True)
    code2 = models.CharField(max_length=2)

SQL对于模型

for City INSERT INTO city VALUES (3955,'Sunnyvale','USA','California',131760);

for Country INSERT INTO country VALUES ('BHS','Bahamas','North America','Caribbean',13878.00,1973,307000,71.1,3527.00,3347.00,'The Bahamas','Constitutional Monarchy','Elisabeth II',148,'BS');

问题1 在上面提到的模型中，如何将Country.code中的代码与City.countrycode相关联，我无法这样做，因为Country模型是在City模型之后声明的。

问题2 以及如何链接Country.capital in国家模型，该模型是与City.name相关的整数。

注意我正在使用InnoDB Engine将.sql文件转换为Postgresql。

Answer 1

看起来你需要声明与字符串相关的foreign key

class City(models.Model):
    name = models.CharField(max_length=35)
    countrycode = models.ForeignKey('Country', blank=True, null=True)


class Country(models.Model):
    code = models.CharField(primary_key=True, max_length=3)
    name = models.CharField(max_length=52)
    capital = models.ForeignKey('Country', blank=True, null=True)

Django - 在同一个模型中有多个外键

1 个答案: