Question

In Django, I have the following models.py

class Product(RandomPrimaryIdModel):
  title = models.CharField(max_length=20, blank=True, null=True)
  price = models.CharField(max_length=20, blank=True, null=True)
  condition = models.CharField(max_length=20, blank=True, null=True)

class Mattress(Product):
  length = models.CharField(max_length=50)
  size = models.CharField(max_length=5)

class Pillow(Product):
  shape= models.CharField(max_length=50)
  comfort= models.CharField(max_length=5)     

The idea is that there’s a “product” model and several “product_type” models. I’m trying to create a database scheme that relates the two. The end goal is so that when I given access to a primary id for an object whose product_type is unknown, I can simply query/filter that object to find out what the product_type is of the object.

I know that sounds a bit confusing, but how would I go about implementing the correct way? The current scheme (the one above) is not the correct solution I believe.

Answer 1

According to the docs on multi-table inheritance you can reference the lowercase name of the model. In your case to find out the “product type” you’d do something like:

product = Product.objects.get(id=12)
try:
    mattress = product.mattress
    is_mattress = True
except Mattress.DoesNotExist:
    is_mattress = False

You could abstract this out to a helper method that would do the tests for you and return the type as a string or enum of some sort.