Hi how would I skip marshalling the Data property in this example?

Once I receive this response, I have to parse this data property as JSON in my frontend because it has been remarshalled. I would like everything to be ready to use from the Go backend. I'm not sure how to do this. Or perhaps I can update the main unmarshaled response with the unmarshaled Data so I don't get this issue; not sure how to do this.

1. Get response from API and unmarshal it
2. Get another API response based on "Data"
3. Unmarshal "Data" and update it
4. Marshal updated "Data" and update original response
5. Final marshal to send to client

Generic Example:

res, err := ... // from API 

type Response struct {
  Id string
  Data string
}

var response Response

json.Unmarshal([]byte(res), &response)

res, err = ... // fetch additional data based on response 

var data map[string]interface{} // Data may have unknown properties

json.Unmarshal([]byte(res), &data)

data["knownproperty"] = "changed"

json, _ := json.Marshal(data)
data := string(json)

// update original response
response.Data = data

// marshal to send to client
json, _ = json.Marshal(response)
data = string(json)

fmt.Fprintf(w, "%v", data)

Thanks