Unable to cast object of type to type

再現は Define.Union、resolveType、resolveValue を中心としている。まず、生成された C# Response 型を使って提供された F# の例を実行する。Foo ブランチが Result.Foo に解決され、FooResult-to-Response.Foo のキャスト例外が発生しなければ完了。

Description

I am receiving an error when converting a response value. The error I receive is "Unable to cast object of type FooResult to type Foo where FooResult is a value of a discriminated Union. Since it compiles, I am unsure of how to debug the issue or how to diagnose the error.

Repro steps

My 'In type Response is a generated C# class provided by a Protobuf generator and my `Out type Result is a Descriminated Union type such that:

public sealed partial class Response {
  public global::Foo Foo { }
  public GetUnionOneOfCase GetUnionCase { }

let FooType =
    Define.Object<Foo>
        (name = "Foo",
         fields = [ Define.Field("message", String, (fun _ e -> e.Message)) ])

type Result =
  | FooResult of Foo
  | BarResult of Bar

let GetResultType = 
  Define.Union<Response, Result>
    (name = "Response",
     options = [ FooType; BarType ],
     resolveType =
       (fun response ->
       match response.GetUnionCase with
       | Response.GetUnionOneofCase.Foo -> upcase FooType
       | Response.GetUnionOneofCase.Bar -> upcase BarType),
     resolveValue = 
       (fun response ->
       match response.GetUnionCase with
       | Response.GetUnionOneofCase.Foo -> FooResult response.Foo
       | Response.GetUnionOneofCase.Bar -> BarResult response.Bar))

Expected behavior

I expect this to resolve response.Foo as Result.Foo.

Actual behavior

System.Exception: Unable to cast object of type 'FooResult' to type 'Response.Foo'

Related information

• OSX
• Dotnet Core