Django的 - 在同一模型中有一個以上的外鍵

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爲模特

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

爲國家 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');

問題1 在上面提到的車型我怎麼能與在Country.code到City.countrycode代碼，我不能夠這樣做，因爲國家模式是城市模型後宣佈。

問題2 而如何鏈接Country.capital in國家模式，即，涉及到City.name一個整數。

注意 我正在將一個.sql文件與InnoDB引擎轉換爲PostgreSQL。

Answer 1

看起來像你需要聲明foreign key通過串

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)