Introduce SIngleton type

[Bert-Proesmans]

I'm currently working with JSON schemas and encountered a use case where an object property is allowed to contain ONLY ONE of the provided objects. Which I named the Singleton type, but another name might fit better.

The generated code declares the property type of a Singleton as a (generic) object, which is enough since resolving/downcasting that object falls under application logic.

[RicoSuter]

Hi, thanks for the PR. But I don't think using "object" or "any" if a schema is a "singleton" is correct.

#13

In your sample, it is only any, if the oneOf schema is also any... Maybe we just have to check in IsAnyType:

IsAnyType => [...current logic] && OneOf.All(s => s.IsAnyType)

[Bert-Proesmans]

You're right, a lot of information is lost by using object. I thought about it for some time but couldn't find a clean way to implement it in C#. I haven't used typescript so i can't attribute to the topic regarding it.

As far as i know the options are building a C-like enum [1], using templates [2], or a very verbose wrapper class [1-Peter N Roth's answer]. All three options have downsides and a compromis should be made for the least unnatural way of writing C#.

My preference lies not with the template option.

update: Regarding your suggestion on the code of my PR; What you propose sounds right but i don't think AnyType definition should change.
That definition with a changed OneOf check wouldn't pass the test for what i meant by Singleton. It's really difficult to abstract the definition to encompass both the current and 'Singleton' domain.

[RicoSuter]

Your unit test passes even when no other changes are made in the codebase... What exactly is your problem?

I think oneOf should be handled with inheritance, i.e. all classes/schemas in oneOf inherit from the base schema...