Return an empty JSON object, valid JSON object, or list of JSON objects in Smithy

Question

I am trying to create a RESTFUL endpoint in Smithy. Basically, the endpoint would have these behaviours:

1. /results : If user navigates to this endpoint, give them back a list of JSON objects or null [{}] if they have none
2. /results/{resultsID}: Give the user a specific JSON object if resultsID is valid and an empty JSON object {} otherwise

My attempt was to create two endpoints as follows:

structure ResultData { //my main JSON object
    user: String,
    UUID: String,
    number1: Float, //all these are optional
    number2: Float,
    number3: Float
}

structure EmptyResponse { }

union Response {
    response: ResultData,
    emptyResponse: EmptyResponse
}


structure ResultDataList { //this structure is for when the user navigates to /results
    member: ResultData //in this case I return an array of JSON objects
}

structure resultsInput { //resultsInput is the http path parameter
    @required
    @httpLabel
    resultsID: String
}


@http(code: 200, method: "POST", uri: "/results", httpHeaders: {"Content-Type": "application/json"})
operation ResultsTotal {
    output: ResultDataList
}



@http(code: 200, method: "POST", uri: "/results/{resultsID}", httpHeaders: {"Content-Type": "application/json"})
operation Results {
    input: resultsInput
    output: Response
}

As you can see, I created two endpoints, one for results and one for results/resultID but I am unsure on how to satisfy the constraints I mentioned above. Additionally, I get an error saying operation shape output relationships must target a structure shape, but found union

Any tips on how I can get this to work?

Answer 1

Smithy requires all responses to be a structure. You should have a separate response structure for each operation. Don't try to re-use them.