在不知道Django中模型名称的情况下获取所有相关对象

Question

I have abstract model:

class CModel(CParent):

    class Meta:
        abstract = True

And have two models based on this abstract model:

class Model1(CModel):
    pass

class Model1_A(models.Model):
    model = models.ForeignKey(Model1, related_name="a")

class Model1_A_B(models.Model):
    model = models.ForeignKey(Model1_A, related_name="b")

and second:

class Model2(CModel):
    def all_obj(self):
        ...
        list = Model2_A_B.objects.filter(model__model__pk=self.pk).all()
        ...

class Model2_A(models.Model):
    model = models.ForeignKey(Model2, related_name="a")

class Model2_A_B(models.Model):
    model = models.ForeignKey(Model2_A, related_name="b")

And now I would like to move function all_obj() to abstact class, so it will be avalible in Model1 too, but for Model1 i need something like this:

list = Model1_A_B.objects.filter(model__model__pk=self.pk).all()

How can i make all_obj() work for any model name?

I came up with something like this:

list = eval(self.a.all()[:1][0].b.all()[:1][0].__class__.__name__).objects.filter(model__model__pk=self.pk)

But i don't think that this is right way to do. And there is problem with that, it is work only if self.a.all()[:1][0] have related objects but this is not always true.

Answer 1

As i can see from this code all your models are the same but with different naming.

Why not create base class for Modeling and create instance to each model?

Regarding the all_obj(self) just make it generic(global)

Answer 2

class CModel(models.Model):
    _related_model = None

   def all_obj(self):
       if self._related_model is None:
           # you could also return None or an EmptyQueryset or whatever
           raise NotImplementedError("CModel subclasses must define '_related_model'")

       # you don't need the `.all()` after a `.filter()`
       return self._related_model.objects.filter(model__model__pk=self.pk)

   # your code here

class Model1(CModel):
    # note that you'll have to define Model_1_A_B before 
    _related_model = Model_1_A_B

    # etc

class Model2(CModel):
    # note that you'll have to define Model_2_A_B before 
    _related_model = Model_2_A_B

    # etc