エラーmodels.pyジャンゴ

Question

多分ここで私はエラー が多く

class Buyers(models.Model): 
    name = models.CharField(max_length= 50) 
    state = models.ForeignKey(StateBuyers, related_name="Buyers", null=True, on_delete=models.CASCADE) 
    city = models.ForeignKey(CityBuyers, related_name="Buyers", null=True, on_delete=models.CASCADE) 
    phonenumber = models.CharField(max_length=15) 
    email = models.EmailField (max_length= 50) 
    notes = models.CharField(max_length=200) 

    def __unicode__(self): 
     return self.name 

    class Meta: 
     db_table = "buyers" 

の1つのインスタンスを作成する必要がありジャンゴに

models.py

class StateBuyers(models.Model): 
    name = models.CharField(max_length=100) 

    def __unicode__(self): 
     return self.name 

    class Meta: 
     db_table = "states" 

class CountiesBuyers (models.Model): 
    state = models.ForeignKey(StateBuyers, on_delete=models.CASCADE) 
    name = models.CharField(max_length=100) 

    def __unicode__(self): 
     return self.name 

    class Meta: 
     db_table = "counties" 


class CityBuyers (models.Model): 
    state = models.ForeignKey(StateBuyers, on_delete=models.CASCADE) 
    county = models.ForeignKey(CountiesBuyers, on_delete=models.CASCADE) 
    name = models.CharField(max_length=100) 

    def __unicode__(self): 
     return self.name 

    class Meta: 
     db_table = "cities" 

を移行を作成するときに、私はエラーを持っています移行時にこのエラーがスローされます アイデアはありますか？

migration error

Answer 1

ややオフトピックが、なぜあなたは規則に従わないのですか？彼らは、デフォルトの状態が郡のために存在する場合

なぜ重複状態と同じであれば、余分なパラメータのための単数形

必要性を全く使用しない

• 単純なモデル名？パフォーマンスの向上？

class NameAsReprMixin(object): 
    def __unicode__(self): 
     return self.name 

class State(models.Model, NameAsReprMixin): 
    name = models.CharField(max_length=100)  


class County(models.Model, NameAsReprMixin): 
    state = models.ForeignKey(State) 
    name = models.CharField(max_length=100) 


class City(models.Model, NameAsReprMixin): 
    county = models.ForeignKey(County) 
    name = models.CharField(max_length=100) 


class Buyer(models.Model, NameAsReprMixin): 
    name = models.CharField(max_length= 50) 
    state = models.ForeignKey(State, related_name="buyers", null=True) 
    city = models.ForeignKey(City, related_name="buyers", null=True) 
    phone_number = models.CharField(max_length=15) 
    email = models.EmailField(max_length= 50) 
    notes = models.CharField(max_length=200) 

その後：

# all city buyers 
City.object.get(...).buyers.all() 

# all state byuers 
State.object.get(...).buyers.all()