如何使用同一张表创建多个多态 Django 模型

Question

I've got a situation where I have one base Django model Rolls , mapped to the table rolls . There are multiple types of rolls, controlled by a column called type . In the older codebase I'm writing a v2 for (used to be PHP), I created subclasses for each type, that controlled setting their own type value, and it worked fine. I can't figure out how to set this up in Django.

I'd like them all to use the same table, and each will derive methods from the base model, but have different implementations for many of those methods. I figure I can write a manager to handle getting back the right values, but I can't figure out how to setup the models.

I tried setting a single base model and then derived other models from it, but those created different tables for each of them. Using managed = False seems the wrong way to go, given the subclasses don't represent tables of their own.

Answer 1

You're on the right track, but I believe you want proxy models and not unmanaged ones, eg proxy = True :

Sometimes, however, you only want to change the Python behavior of a model – perhaps to change the default manager, or add a new method.

This is what proxy model inheritance is for: creating a proxy for the original model. You can create, delete and update instances of the proxy model and all the data will be saved as if you were using the original (non-proxied) model. The difference is that you can change things like the default model ordering or the default manager in the proxy, without having to alter the original.

Then you could override each subclass' save method to set the correct type , and each subclass' default query manager to filter on that type .