How to get underlying value from a reflect.Value in golang?

Question

So I found some code that help me get started with reflection in Go (golang), but I'm having trouble getting a the underlying value so that I can basically create a map[string]string from a struct and it's fields.

Eventually, I'd like to make the result into a map[string]interface{}, but this one issue is kind of blocking me.

The code I have at the moment:

package main  import (     "fmt"     "reflect" )  type Foo struct {     FirstName string `tag_name:"tag 1"`     LastName  string `tag_name:"tag 2"`     Age       int  `tag_name:"tag 3"` }  func inspect(f interface{}) map[string]string {      m := make(map[string]string)     val := reflect.ValueOf(f).Elem()      for i := 0; i < val.NumField(); i++ {         valueField := val.Field(i)         typeField := val.Type().Field(i)          f := valueField.Interface()         val := reflect.ValueOf(f)         m[typeField.Name] = val.String()     }      return m }  func dump(m map[string]string) {      for k, v := range m {         fmt.Printf("%s : %s\n", k, v)     } }  func main() {     f := &Foo{         FirstName: "Drew",         LastName:  "Olson",         Age:       30,     }      a := inspect(f)      dump(a) } 

The output from running the code:

FirstName : Drew LastName : Olson Age : <int Value> 

From what I understand the output for FirstName and LastName are actual reflect.Value objects but for strings the String() method on value just outputs the underlying String. I'd like to either get the int and change it into a string, but from the relfect package documentation I'm not immediately seeing how that's done.

Soo.... How do I get the underlying value from a reflect.Value in golang?

Answer 1

A good example of how to parse values is the fmt package. See this code.

Using the mentioned code to match your problem would look like this:

switch val.Kind() { case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:     m[typeField.Name] = strconv.FormatInt(val.Int(), 10) case reflect.String:     m[typeField.Name] = val.String()     // etc... } 

Basically you need to check for all available Kinds.