How do you loop through the fields in a Golang struct to get and set values in an extensible way?

Question

I have a struct Person.

type Person struct {
    Firstname string       
    Lastname  string       
    Years     uint8       
}

Then I have t

Answer 1

I don't even know how many ways this can go wrong...

package main

import (
    "fmt"
    "encoding/json"
)

type Serializable interface {
    fromMap(map[string]interface{}) error
    toMap() (map[string]interface{}, error)
}

type Person struct {
    Firstname string       
    Lastname  string       
    Years     uint8       
}

func (p *Person) fromMap(m map[string]interface{}) error {
    b, err := json.Marshal(m)
    if err != nil {
        return err
    }

    if err := json.Unmarshal(b, p); err != nil {
        return err
    }
    return nil
}

func (p Person) toMap() (map[string]interface{}, error) {
    b, err := json.Marshal(p)
    if err != nil {
        return nil, err
    }
    m := map[string]interface{}{}
    if err := json.Unmarshal(b, &m); err != nil {
        return nil, err
    }
    return m, nil
}

func copy(p1 Serializable, p2 Serializable) error {

    m1, err := p1.toMap()
    if err != nil {
        return err
    }

    m2, err := p2.toMap()
    if err != nil {
        return err
    }

    for k := range m1 {
        m2[k] = m1[k]
    }

    if err := p2.fromMap(m2); err != nil {
        return err
    }
    return nil
}

func main() {
    p1 := Person{
        "Mary",
        "Jane",
        26,
    }

    p2 := Person {
        "Random",
        "Lady",
        26,
    }

    if err := copy(&p1, &p2); err != nil {
        fmt.Printf("ERR: %s\n", err.Error())
        return
    }

    fmt.Printf("%v\n", p2)

}