Create instance of struct via reflection and set values

what I try to do

I try to pass an instance of a struct - including json tags to a func, create a new instance, and set value on field
after this i try to serialize (JSON), but the values are empty

NOTICE: i looked up loads of articles on SO about setting values via reflection, but it seems i missed a little detail

struct definition

this part defines the struct with json and xml tags

type Person struct {
    Name string `json:"Name" xml:"Person>FullName"`
    Age  int    `json:"Age" xml:"Person>Age"`
}

create instance (+wrapping into empty interface)

afterwards I create an instance and store it in an interface{} - why? because in my production code this stuff will be done in a func which accepts a interface{}

var iFace interface{} = Person{
		Name: "Test",
		Age:  666,
	}

creating a new instance of the struct and setting values via reflection

iFaceType := reflect.TypeOf(iFace)
	item := reflect.New(iFaceType)
	s := item.Elem()
	if s.Kind() == reflect.Struct {
		fName := s.FieldByName("Name")
		if fName.IsValid() {
			// A Value can be changed only if it is
			// addressable and was not obtained by
			// the use of unexported struct fields.
			if fName.CanSet() {
				// change value of N
				switch fName.Kind() {
				case reflect.String:
					fName.SetString("reflectedNameValue")
					fmt.Println("Name was set to reflectedNameValue")
				}
			}
		}
		fAge := s.FieldByName("Age")
		if fAge.IsValid() {
			// A Value can be changed only if it is
			// addressable and was not obtained by
			// the use of unexported struct fields.
			if fAge.CanSet() {
				// change value of N
				switch fAge.Kind() {
				case reflect.Int:
					x := int64(42)
					if !fAge.OverflowInt(x) {
						fAge.SetInt(x)
						fmt.Println("Age was set to", x)
					}
				}
			}
		}
	}

Question

what am I doing wrong?
in production code I fill multiple copies with data and add it to a slice...
but this only makes sense if the json tags are kept in place and the stuff serializes just the same way.

code sample for play

package main

import (
	"encoding/json"
	"fmt"
	"reflect"
)

func main() {
	type Person struct {
		Name string `json:"Name" xml:"Person>FullName"`
		Age  int    `json:"Age" xml:"Person>Age"`
	}

	var iFace interface{} = Person{
		Name: "Test",
		Age:  666,
	}
	fmt.Println("normal: \n" + JSONify(iFace))
	iFaceType := reflect.TypeOf(iFace)
	item := reflect.New(iFaceType)
	s := item.Elem()
	if s.Kind() == reflect.Struct {
		fName := s.FieldByName("Name")
		if fName.IsValid() {
			// A Value can be changed only if it is
			// addressable and was not obtained by
			// the use of unexported struct fields.
			if fName.CanSet() {
				// change value of N
				switch fName.Kind() {
				case reflect.String:
					fName.SetString("reflectedNameValue")
					fmt.Println("Name was set to reflectedNameValue")
				}
			}
		}
		fAge := s.FieldByName("Age")
		if fAge.IsValid() {
			// A Value can be changed only if it is
			// addressable and was not obtained by
			// the use of unexported struct fields.
			if fAge.CanSet() {
				// change value of N
				switch fAge.Kind() {
				case reflect.Int:
					x := int64(42)
					if !fAge.OverflowInt(x) {
						fAge.SetInt(x)
						fmt.Println("Age was set to", x)
					}
				}
			}
		}
	}
	fmt.Println("reflected: \n" + JSONify(item))
}

func JSONify(v interface{}) string {
	var bytes []byte
	bytes, _ = json.MarshalIndent(v, "", "\t")
	return string(bytes)
}

Your item is of type reflect.Value. You have to call Value.Interface() to obtain the value wrapped in it:

fmt.Println("reflected: \n" + JSONify(item.Interface()))

With this change, output will be (try it on the Go Playground):

normal: 
{
"Name": "Test",
"Age": 666
}
Name was set to reflectedNameValue
Age was set to 42
reflected: 
{
"Name": "reflectedNameValue",
"Age": 42
}

reflect.Value itself is also a struct, but obviously trying to marshal it will not be identical to marshaling a Person struct value. reflect.Value does not implement marshaling the wrapped data to JSON.