V2 - Why is OpenAPISchema.Type of type "object"?

[baywet]

This provides a really poor development experience, forcing the consumer to implement complex type assertions when it shouldn't be required.

And then we do things like those:

OpenAPI.NET/src/Microsoft.OpenApi/Models/OpenApiSchema.cs

Line 839 in 3c64451

{

Which is not only going to be slow, but also problematic for people using AOT/trimming.

We already know that OAS 3.1 and Json Schema only support the following types:

• null
• boolean
• object
• array
• number
• string

(maybe we could add compatibility with the integer mess).

Why not instead:

• Define an enum for those types
• Make the type property, an array/list/enumerable of that enum
• When serializing as v2/v3, ensuring that we emit the right compatible information.

[darrelmiller]

I hadn't noticed this. I agree that making the type property of type object is not going to be a great experience. However, I'm not sure making it an array is the right choice considering how commonly devs will only want to set a single value.

Could we make a HttpMethod style class that does some operator overloading to handle assigning both simple values and arrays?

[calebkiage]

According to the doc comments, it says that:

Value MUST be a string in V2 and V3

Is there a situation where it's not a string or an array of strings?

I agree with making it an enum since we know the possible values. We can even add a member for unexpected types and show a validation error.

[baywet]

@darrelmiller with modern CSharp (12) people can simply write collection expressions

schema.Type = [SchemaType.Object];

(assuming we go with an enum)

@calebkiage I think this is simply an abstract of the JSON schema spec at the end, the possible values here being constrained to a set we know in advance, we might as well use an enum.

[baywet]

Interestingly enough STJ chose a flaggable enum, which is another option we haven't considered.
https://github.com/dotnet/runtime/blob/5e9a425ed90f30f92eb3d2d4b25179efe8255232/src/libraries/System.Text.Json/src/System/Text/Json/Schema/JsonSchemaType.cs#L11

They do not have a developer experience requirement though, since everything is internal (and that's too bad since we could have reused a lot of what they've built)