Enumeration handling

[nickevansuk]

Hi @RehanSaeed! We're porting Schema.NET to PHP and Ruby, and were wondering if you could help us out with a question we had on enumeration handling...

https://schema.org/PaymentCard is both an https://schema.org/Enumeration and a https://schema.org/Service, and in Schema.NET it is treated only as an enum without a corresponding class.

We're really interested in the logic you're applying here and the rationale for it?

[RehanSaeed]

That's cool.

Interesting, I was not aware of that. I wonder how many other types are both enumerations and classes. That sounds like a bug. In this case, we should add a suffix to the enumeration or class, and then generate both enum and class types.

We use two JSON-LD files downloaded from schema.org to drive the creation of all the types. Given time, I'd look in there to see how PaymentCard was defined.

[nickevansuk]

Interesting! Maybe a bug... We should raise it with the schema.org folks over at that repo if so? Couldn’t find anything about it in their issues, but you might find something I missed?

Suffix would break implementations like ours that rely on the predictability of names to generate subclasses automatically - perhaps we could use .NET namespaces to keep enums separate and allow them to be predictably referenced? The IDE would then help users with this too?

Look forward to hearing your findings

[RehanSaeed]

The link to the two JSON-LD files can be found in the schema generating Tool project. I would check in there first. It may be a bug with schema.org or it could be our code not handling it.

Namespaces is another way to go. Not sure what I'd choose yet. I'd want to know how often this happens before I decided.

[nickevansuk]

Oh I see, it's definitely coming from schema.org (PaymentMethod subclasses Enumeration, FinancialProduct subclasses Service):

{
  "@id": "http://schema.org/PaymentCard",
  "@type": "rdfs:Class",
  "http://purl.org/dc/terms/source": {
    "@id": "http://www.w3.org/wiki/WebSchemas/SchemaDotOrgSources#FIBO"
  },
  "rdfs:comment": "A payment method using a credit, debit, store or other card to associate the payment with an account.",
  "rdfs:label": "PaymentCard",
  "rdfs:subClassOf": [
    {
      "@id": "http://schema.org/PaymentMethod"
    },
    {
      "@id": "http://schema.org/FinancialProduct"
    }
  ]
},

Looks like this "Enumeration is also a Class" issues applies to:

• All the subclasses of https://schema.org/MedicalEnumeration (although these aren't part of core schema.org)
• https://schema.org/PaymentCard
• https://schema.org/QualitativeValue and its subclasses (though the https://schema.org/QualitativeValue page seems to have a bug)

So there are quite a few in there... if this isn't something you're aware of perhaps we raise it with the schema.org mailing list / GitHub?

[RehanSaeed]

You could ask them to make sure but I'm assuming having an enum and class with the same name is allowed by schema.org.

When you say there are quite a few, how many?

[nickevansuk]

23 that seem to have properties according to the GUI - however: https://schema.org/DrugClass shows that even a straightforward “Enumeration” can be used as a class, without subclassing anything except Enumeration... so not sure whether it would be correct to assume that this applies to all Enumerations?

Perhaps this is where we need guidance?

[RehanSaeed]

It might be worth asking them how we should handle this scenario after explaining what Schema.NET has achieved. I'm not certain what the best resolution is at the moment.

[nickevansuk]

Hey @RehanSaeed just to let you know I've reached out to the schema.org mailing list on this question.

For now we're going to implement the following (which seems to match what Schema.NET already does):

• Any rdfs:Class that subclasses https://schema.org/Enumeration (either directly or indirectly) should be strictly an enum, and all other inheritance for that rdfs:Class should be ignored

If they come back with anything on the mailing list (specifically around https://schema.org/PaymentCard) we can pick it up then and perhaps discuss how to approach across both projects?

[RehanSaeed]

I'd raise an issue on their GitHub too. They do have a lot of open issues and I imagine that they are having a hard time keeping up but I've always got a response from the maintainers.

[RehanSaeed]

Please feel free to open a bug once you have some answers.