如何将一个空结构封送为一个空数组

Question

I'm not sure if the title accurately explains what I'm looking to do so I'll try to give as many details as I can.

I have a struct with nested structs that I am marshalling and sending out to an API. There are some requests that require my lowest level struct to be empty and I need its parent parameter to equal an empty array instead of null. If I use omitempty on the parameter, it will completely remove it from my request and the request will fail. If I use omitempty on the parameter's parameters, it causes the value to be null and the request will fail.

Here are the structs I am using for the request:

// SubscribeRequest is the top level wrapper for ICWS request bodies
SubscribeRequest struct {
    ClientStateIsFresh bool           `json:"clientStateIsFresh"`
    StatisticKeys      []StatisticKey `json:"statisticKeys"`
}

// StatisticKey is a value we want to pull from ICWS reporting
StatisticKey struct {
    StatisticIdentifier string       `json:"statisticIdentifier"`
    ParameterValueItems []Parameter `json:"parameterValueItems"`
}

// Parameter is a filter applied when pulling statistics
Parameter struct {
    ParameterTypeID string `json:"parameterTypeId"`
    Value           string `json:"value"`
}

And I need the marshalled JSON to look like this:

{
    "clientStateIsFresh":true,
    "statisticKeys":
    [
        {
            "statisticIdentifier":"inin.system.interaction:ActiveCalls",
            "parameterValueItems":
            [

            ]
        }
    ]
}

If I have anything other than this, the request fails. I don't get any errors, but it doesn't return any usable data. Any suggestions on how to accomplish this?

*Note: I did try using []*Parameter instead of []Parameter, but it gave me the same result.

Answer 1

If you want an empty array, you have to provide an empty slice.

StatisticKey{
    StatisticIdentifier: "id.string",
    ParameterValueItems: []Parameter{},
}