How to represent nested union?

[RafalFilipek]

Hi,

Lets say I have 4 models:

model Foo {type: "FOO"}
model BarA {type: "BAR", role: "A"}
model BarB {type: "BAR", role: "B"}
model Biz {type: "BIZ"}

I have a problem with implementing union where response is in form:

@discriminator("type")
union Items {
  FOO: Foo,
  BAR: BarA | BarB, // I know this is invalid syntax
  BIZ: Biz,
}

My first though was to create an additional union for BarA and BarB but this gives me an error :

@discriminator("role")
union Bar {
  A: BarA,
  B: BarB,
}

Union variant "BAR" must be a model type.

I also tried with additional model that BarA and BarB and extend:

@discriminator("role")
model Bar { ... }

but also no luck.

Is there any way to represent this with TypeSpec?

Thanks,

Rafał

[mikekistler]

Here's a suggestion:

model Foo {type: "FOO"}
@discriminator("role")
model Bar {
  type: "BAR"
}
model BarA extends Bar {type: "BAR", role: "A"}
model BarB extends Bar {type: "BAR", role: "B"}
model Biz {type: "BIZ"}

@discriminator("type")
union Items {
  FOO: Foo,
  BAR: Bar,
  BIZ: Biz,
}

Playground link

Is this what you wanted?