Convert map[interface {}]interface {} to map[string]string

Question

From a source I cannot influence I am given data in a map, which arrives as map[interface {}]interface {}.

I need to process the contained data, prefera

Answer 1

A secure way to process unknown interfaces, just use fmt.Sprintf()

https://play.golang.org/p/gOiyD4KpQGz

package main

import (
    "fmt"
)

func main() {

    mapInterface := make(map[interface{}]interface{})   
    mapString := make(map[string]string)

    mapInterface["k1"] = 1
    mapInterface[3] = "hello"
    mapInterface["world"] = 1.05

    for key, value := range mapInterface {
        strKey := fmt.Sprintf("%v", key)
        strValue := fmt.Sprintf("%v", value)

        mapString[strKey] = strValue
    }

    fmt.Printf("%#v", mapString)
}

Answer 2

// data is map[string]interface{}

form := make(map[string]string)

for k, v := range data {
    form[k] = v.(string)
}

Answer 3

Perhaps I misunderstand the question, but would this work?

m := make(map[interface{}]interface{})
m["foo"] = "bar"

m2 := make(map[string]string)   

for key, value := range m {        
    switch key := key.(type) {
    case string:
        switch value := value.(type) {
        case string:
            m2[key] = value
        }
    }
}