如何在Django中建模（继承的模型，其中每个继承的模型都有唯一的方法）

Question

How to model this in django:

1) have a base network of manufacturers

2) under each network their might be several distributors

3) a user of the system can access items through the distributor

4) if a user access the item through the distributor we want that item to be translated where each manufacturer will have their own translation

class Manufacturer(models.Model):
    networkname = models.CharField(max_length=128)

    class Meta:
        proxy = True

class Distributor(models.Model):
    man = models.ForeignKey(Manufacturer)

class ManuType1(Manufacturer):
    def translate(self, str):
        return 'translate'

class ManuType2(Manufacturer):
    def translate(self, str):
        return 'translate'

In this scenario we will get a request for a certain Distributor. We identify that distributor and we want to call that distributors manufacturers translate method. Does this look like a way to model this in django (I'm sure there are many ways to do this) so any input/feedback is useful.

Where I run into problems (not knowing python well enough perhaps) is given a Distributor with ManuType1 How do I call the translate function at runtime?

This is probably a well explored pattern using other terms, just not sure how to express it exactly.

Answer 1

If dist is an instance of Distributor, then you can do dist.man to get the Manufacturer instance. Due to the way multi-table inheritance works in Django, you'll need to access the OneToOneField that exists on the Manufacturer to the subclass instance. The problem lies in figuring out which subclass instance exists. This can be made easier by storing the ContentType of the subclass in the Manufacturer instance .