How can I parse JSON in GoLang if nested content uses dynamic keys?

Question

I received JSON below from a client API but i am struggling to get nested JSON content. How can I parse it if the inner keys are dynamic?

const jsonStream = `
{
    "items": {
        "bvu62fu6dq": {
            "name": "john",
            "age": 23,
            "xyz": "weu33s"
        },
        "iaxdw23fq": {
            "name": "kelly",
            "age": 21,
            "xyz": "weu33s"
        }
    }
}`

This is what i have tried below by looping the map to extract the value of name and age from above JSON string; but it returns map with nil value as a result. goplaygound

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}
type Item struct {
    Contact struct {
        Info map[string]Person
    } `json:"items"`
}

func main() {
    dec := json.NewDecoder(strings.NewReader(jsonStream))
    for {
        var item Item
        if err := dec.Decode(&item); err == io.EOF {
            break
        } else if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("%s\n", item.Contact.Info["bvu62fu6dq"].Name)
    }
}

Could you edit your question explaining the point of the unique keys? It is only mentioned in the title — Mario Trucco
– Mario Trucco, Commented Sep 27, 2015 at 7:19
It will be easier if you say that, and in what form you need to get. — user4651282
– user4651282, Commented Sep 27, 2015 at 8:19

Jeffrey Martinez · Accepted Answer · 2015-09-27 10:08:25Z

6

Try this instead, looks like you just have your structure set up incorrectly:

http://play.golang.org/p/VRKbv-GVQB

You need to parse the entire json string, which is an object that contains a single element named items. items then contains a map of string -> Person objects.

If you only want to extract name and age from each person, you do it by grabbing data.Items["bvu62fu6dq"].Name.

If you want dynamic keys inside the Person, you'll need to do map[string]interface{} instead of Person in order to capture the dynamic keys again. It would look something like:

type Data struct {
    Items map[string]map[string]interface{} `json:"items"`
}
...
fmt.Printf("%v\n", data.Items["bvu62fu6dq"]["name"]
fmt.Printf("%v\n", data.Items["bvu62fu6dq"]["age"]
fmt.Printf("%v\n", data.Items["bvu62fu6dq"]["xyz"]

edited Sep 27, 2015 at 10:08

answered Sep 27, 2015 at 8:44

Jeffrey Martinez

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