Go Lang json解码映射

Question

How can I map each element to struct or map. Base on the json data that has different types.

{
  profile: {
    execution_time: 34,
    server_name: "myServer.net"
  },
  result: "ok",
  ret: [
    {
      alias: "asda444444",
      all_parents: [
        123,
        2433369,
        243628,
        2432267,
        62
      ],
      bankrupt: false,
      block: false,
      card: null
    }
  ]
}

I had tried this already. But not work as expected.

var o map[string]interface{}
err := json.Unmarshal(data, &o)
if err != nil {
        revel.INFO.Println("Json Decode Error", err)
    }
fmt.Println(o)

By this way, I can only get o["ret"]. What I really want is o["ret"]["alias"] or o["ret"]["all_parents"].

Any suggestions or tips will helps. Thanks.

Answer 1

You can use the map[string]interface{} result and typecast the relevant parts, eg:

o["ret"].([]interface{})

would get the array and continue so on. However, this is tedious and you need to check for values being set etc as well.

Instead, I'd recommend you use the handy JSON to Go tool that can automatically generate a struct definition for you to paste into your Go code when given some input JSON.

Obviously you might need to amend this to suit your needs as you know what valid formats the input can take. However, this tool saves a lot of tedious boilerplate code writing!

For example, for the JSON above, it generates:

type AutoGenerated struct {
    Profile struct {
        ExecutionTime int `json:"execution_time"`
        ServerName string `json:"server_name"`
    } `json:"profile"`
    Result string `json:"result"`
    Ret []struct {
        Alias string `json:"alias"`
        AllParents []int `json:"all_parents"`
        Bankrupt bool `json:"bankrupt"`
        Block bool `json:"block"`
        Card interface{} `json:"card"`
    } `json:"ret"`
}