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NoEncoderException
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I have an Rpc call that returns seq<Types.AliasedId * Types.Data> where Types.AliasedID is an int and Types.Datum is defined as:

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[<NamedUnionCases>]
    type Datum = 
        | Discrete of dd: string
        | Continuous of cd: float
        | Boolean of bd: bool
        | Date of dtd: DateTime

The call returns a 500 at runtime and, so I've just noticed, produces a compile-time complaint: Cannot encode the return type to JSON.

The console output produces:

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Exception thrown: 'WebSharper.Core.Json.NoEncodingException' in WebSharper.Core.dll
Exception thrown: 'WebSharper.Core.Json.NoEncoderException' in WebSharper.Core.dll
Exception thrown: 'WebSharper.Core.Json.NoEncoderException' in FSharp.Core.dll

I've been unable to find information on any necessary annotations, is there something special I need to do to Datum to make it encodable?

.

The problem is not with your Datum type; the problem is seq. You can only pass certain concrete sequence types through RPC: list, array, ResizeArray, Set, Map.

I do believe that we have it in our plans to make this exception more explicit about why exactly a type cannot be encoded, which would have helped a lot here.

By on 3/23/2017 10:45 AM ()

Ah, excellent. Thanks.

By on 3/23/2017 3:09 PM ()

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