How to convert map[string]interface{} into what the underlying data structure actually is? (JSON-related)

[Po Tatoe]

Hi,

I have this JSON data...

{

  "bar": {

    "a": "b",

    "x": "y"

  }

}

...which is a map[string]map[string]string

However, json.UnMarshal gives me a map[string]interface {}

How do I convert that back into map[string]map[string]string?

I've tried:

1) .(map[string]map[string]string) but get a panic.

2) Range down into the data structure, but I get: "cannot range over type interface {}".

FYI, my program has no way of knowing the names of the fields/keys in advance, but every key and value is a string and thus will fit into map[string]map[string]string.

Here's my code:

package main

import (

"encoding/json"

"fmt"

"io/ioutil"

"os"

"reflect"

)

func main() {

/*

  {

    "bar": {

      "a": "b",

      "x": "y"

    }

  }

*/

fileContents, err := ioutil.ReadFile("./json.txt")

if err != nil {

fmt.Println(err)

os.Exit(1)

}

var f interface{}

err = json.Unmarshal(fileContents, &f)

if err != nil {

fmt.Println(err)

os.Exit(1)

}

fmt.Println(f)  // map[bar:map[a:b x:y]]

fmt.Println(reflect.TypeOf(f)) // map[string]interface {}

// now how do I convert f into map[string]map[string]string ?

}

[Andrew Bursavich]

Just decode it into a value of the correct type from the get go ;)

http://play.golang.org/p/zD6fBClIyW

[Andrew Stewart]

This solves my problem and is exactly what I was looking for - thank you very much Andrew!

On Mon, Jan 5, 2015 at 10:13 PM, Andrew Bursavich <aburs...@gmail.com> wrote:

Just decode it into a value of the correct type from the get go ;)

http://play.golang.org/p/zD6fBClIyW

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