Decode HTTP Response - version 2

DataFromResponse.v2.go

import (
	"encoding/json"
	"errors"
	"net/http"
)

type CustomerStringId struct {
  ID    string `json:"id"`
  Name  string `json:"name"`
}

type CustomerIntId struct {
  ID    string `json:"id,int"` // decode it from int in JSON to string
  Name  string `json:"name"`
}

func dataFromResponse(r *http.Response) (*Customer, error) {
  // copy the content of response body, so it can be reused later
  body, err := ioutil.ReadAll(r.Body)
  if err != nil {
    return nil, util.Error(util.Internal, "failed to read the body of response: %s", err.Error())
  }
  defer r.Body.Close()
  type Response struct {
    Customer *CustomerStringId `json:"data"`
  }
  // try to decode body to CustomerStringId
  res := Response{}
  err = json.Unmarshal(body, &res)
  if err != nil {
    // if failed, try to decode body to CustomerIntId
    type Response struct {
        Customer *CustomerIntId `json:"data"`
    }

    resInt := Response{}
    if err := json.Unmarshal(body, &resInt); err != nil {
      return nil, errors.New("failed to convert response to Customer: %s", err.Error())
    }
    // copy CustomerIntId to CustomerStringId
    res.Customer.ID = resInt.Customer.ID
    res.Customer.Name = resInt.Customer.Name
  }
  return res.Customer, nil
}