How to get values of a map interface with reflect in Go?

Question

I'm struggling to get the value of an interface map in Go.

val := reflect.ValueOf(Schema)
fmt.Println("VALUE = ", val)
fmt.Println("KIND = ", val.Kind())
if val.Kind() == reflect.Map {
    fmt.Println("len = ", val.Len())
    for key, element := range val.MapKeys() {
        fmt.Println(key, element) // how to get the value?
    }
}

This outputs:

VALUE =  map[testString:foobar testInt:1 testBoolean:true testNumber:1 testDateTime:2017-10-06 08:15:30 +0100 +0100]
KIND =  map
len =  5
0 testString
1 testInt
2 testBoolean
3 testNumber
4 testDateTime

My question:
How can I get the type and value of the map items?

Answer 1

You were close, you can use the key returned form MapKeys and then use MapIndex to get the value of the map key. Below I use a switch statement to convert the value of the interface to the correct type.

package main

import (
    "fmt"
    "reflect"
)

func main() {
    Schema := map[string]interface{}{}
    Schema["int"] = 10
    Schema["string"] = "this is a string"
    Schema["bool"] = false

    val := reflect.ValueOf(Schema)
    fmt.Println("VALUE = ", val)
    fmt.Println("KIND = ", val.Kind())

    if val.Kind() == reflect.Map {
        for _, e := range val.MapKeys() {
            v := val.MapIndex(e)
            switch t := v.Interface().(type) {
            case int:
                fmt.Println(e, t)
            case string:
                fmt.Println(e, t)
            case bool:
                fmt.Println(e, t)
            default:
                fmt.Println("not found")

            }
        }
    }
}

Program Output:

VALUE =  map[int:10 string:this is a string bool:false]
KIND =  map
int 10
string this is a string
bool false