Python：如何繼承和重寫有查詢集的方法？

Question

我有2classes A和B：

class A(ListView): 
     model=Model_name 
     def get_queryset(self): 
      instance = self.get_user_by_credential(...) 
      if instance: 
       model_instance = self.model.objects.get(id=instance.id) 
       some_objects= self.Model_name.objects.filter(content_id=5, object_id=model_instance.id) 
       return some_objects 
      return [] 



class B(A,UserObject): 
     model=B_model 
     param='foo' 
     def get_queryset(self): 
      instance = self.get_user_by_credential(...) 
      if instance: 
       model_instance = self.model.objects.get(id=instance.id, param=param) 
       some_objects= Model_name.objects.filter(content_id=5, object_id=model_instance.id) 
       return some_objects 
      return [] 

我如何可以覆蓋A父類的方法，並添加參數的2類之間的差別僅僅是在B

的查詢集的param到子類B的查詢集？

Answer 1

你可以只讓一個get_model_instance方法，然後使用在A裏面執行，這樣就可以刪除B.

def get_model_instance(self): 
    instance = self.get_user_by_credential(...) 
    if instance: 
     return self.model.objects.get(id=instance.id) 
    return None 

def get_model_instance(self): 
    instance = self.get_user_by_credential(...) 
    if instance: 
     return self.model.objects.get(id=instance.id, param=param) 
    return None 

，或者實現由丹尼爾·羅斯曼

def get_model_instance(self, instance): 
    ...