One operation with multiple output types

[khanetor]

I have a situation where a single operation will have to return responses in many different shapes, for legacy reason.

In this single endpoint, the responses can look like the following

{
    "contact":true,
    "input":false,
    "license":false,
    "credentials":false,
    "camera-exist":false
}

{
    "request":"OK",
    "camera_api_version":"3.4.0",
    "product_version":"1.6.15",
    "product":"DataManager",
    "time":1653485942
}

ok

1516342680.0

{
  "status": "CM_OK", 
  "date": "1516342680.0"
}

I tried using union, but that is not valid for the output. Any recommendation? Or should I go back to using http4s directly in this case?

[kubukoz]

I think you can use a union, but with the @Untagged trait. Your output type will still be a struct, but it'll have one member annotated with @httpPayload.

[Baccata]

Jakub is right. See https://disneystreaming.github.io/smithy4s/docs/codegen/unions#untagged-union

[khanetor]

I think you can use a union, but with the @Untagged trait. Your output type will still be a struct, but it'll have one member annotated with @httpPayload.

I came up with something like this, but it does not work

@http(method: "POST", uri: "/api", code: 200)
operation Report {
    input: CameraQuery,
    output: UnionResponse
}

structure Response1 {
    @required
    contact: Boolean

    @required
    input: Boolean

    @required
    license: Boolean

    @required
    credentials: Boolean

    @required
    cameraExist: Boolean
}

structure Response2 {
    @required
    request: String

    @required
    camera_api_version: String

    @required
    product_version: String

    @required
    product: String

    @required
    time: Integer
}

structure Response3 {
    @required
    status: String

    @required
    date: String
}


@untagged
union UnionResponse {
    case1: Response1
    case2: Response2
    case3: Response3
    case4: String
    case5: Float
}

The error is

[error] stack trace is suppressed; run last Compile / smithy4sCodegen for the full output
[error] (Compile / smithy4sCodegen) software.amazon.smithy.model.validation.ValidatedResultException: Result contained ERROR severity validation events: 
[error] [ERROR] zoined.smithy4s.axis#Report: operation shape `output` relationships must target a structure shape, but found (union: `zoined.smithy4s.axis#UnionResponse`) | Target /Users/kha/Projects/Zoined/Axis-camera-relay-service/src/main/smithy/AxisCameraService.smithy:15:1
[error] Total time: 0 s, completed 28 Nov 2022, 13.44.21

So we still have not resolved the issue where the output has to be a structure, and we need a union in place of a structure. So I think I still don't fully understand what you meant by that I can use a union, but the output has to be a structure.

[Baccata]

The fact that the input/output of an operation has to be a structure doesn't necessarily meant that the body of your http request/response has to be one too : you can use the @httpPayload trait to solve this problem 😸

[khanetor]

Oh, now I see what you meant.

Here is what works

@http(method: "POST", uri: "/api", code: 200)
operation Report {
    input: CameraQuery,
    output: TheResponse
}

structure Response1 {
    @required
    contact: Boolean

    @required
    input: Boolean

    @required
    license: Boolean

    @required
    credentials: Boolean

    @required
    cameraExist: Boolean
}

structure Response2 {
    @required
    request: String

    @required
    camera_api_version: String

    @required
    product_version: String

    @required
    product: String

    @required
    time: Integer
}

structure Response3 {
    @required
    status: String

    @required
    date: String
}


@untagged
union UnionResponse {
    case1: Response1
    case2: Response2
    case3: Response3
    case4: String
    case5: Float
}

structure TheResponse {
    @required
    @httpPayload
    response: UnionResponse
}

[khanetor]

Thank you :)