Inheritance - child classes aren't serialised properly

[davidwneary]

I'm not sure if this is a feature request or bug.

Say I have the following Documents defined:

class Company(Document):
    products = EmbeddedDocumentListField(Product)

class Product(EmbeddedDocument):
    name = StringField()

    meta = {
        'allow_inheritance': True
    }

class ClothingProduct(Product):
    fabric = StringField()

class FoodProduct(Product):
    ingredients = ListField()

and I have a schema for Company:

class CompanySchema(Schema):
    class Meta:
        model = Company

and I run the following code:

productA = ClothingProduct(name='tshirt', fabric='cotton')
productB = FoodProduct(name='sausage', ingredients=['Pork', 'sage', 'breadcrumbs'])
company = Company(products=[productA, productB])
result = CompanySchema(company).dump()

result is:

{
"products": [
        {
          "_cls": "ClothingProduct",
          "name": "tshirt"
        },
        {
          "_cls": "FoodProduct",
          "name": "sausage"
        }
      ]
}

whereas I would expect it to be:

{
"products": [
        {
          "_cls": "ClothingProduct",
          "fabric": "cotton",
          "name": "tshirt"
        },
        {
          "_cls": "FoodProduct",
          "ingredients": ['Pork', 'sage', 'breadcrumbs'],
          "name": "sausage"
        }
      ]
}

I understand why this could be the case since when we create the schema, we only have the Product class to go off, but I wondered if there was a way around this. Perhaps leveraging .__subclasses__()? I can have a closer look myself but just wanted to check if this was something that had been considered before or if it is not expected behaviour.

Cheers Dave