如何在Django中实现Rails的多态性/STI？

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey

class BaseModel(models.Model):
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')

    class Meta:
        abstract = True

class ModelA(BaseModel):
    # 添加子类模型的字段
    name = models.CharField(max_length=100)

class ModelB(BaseModel):
    # 添加子类模型的字段
    value = models.IntegerField()

from django.shortcuts import get_object_or_404

def my_view(request, model_id):
    # 获取父类模型的实例
    base_model = get_object_or_404(BaseModel, pk=model_id)

    # 根据content_type字段的值确定具体的子类模型
    if base_model.content_type.model == 'modela':
        # 处理ModelA的逻辑
        model_a = base_model.content_object
        # ...

    elif base_model.content_type.model == 'modelb':
        # 处理ModelB的逻辑
        model_b = base_model.content_object
        # ...