Go getValueFromPath()

개요

Go getValueFromPath()

package main

import (
	"fmt"
	"reflect"
	"strings"
)

type User struct {
	Name    string
	Profile Profile
}

type Profile struct {
	Email string
	Phone string
}

func main() {
	user := User{
		Name: "John Doe",
		Profile: Profile{
			Email: "john.doe@example.com",
			Phone: "123-456-7890",
		},
	}

	fmt.Println(getValueFromPath(user, ".X"))             // <nil>
	fmt.Println(getValueFromPath(user, ".Name"))          // "John Doe"
	fmt.Println(getValueFromPath(user, ".Profile"))       // {john.doe@example.com 123-456-7890}
	fmt.Println(getValueFromPath(user, ".Profile.Email")) // "john.doe@example.com"
	fmt.Println(getValueFromPath(user, ".Profile.Phone")) // "123-456-7890"
}

func getValueFromPath(v interface{}, path string) interface{} {
	fields := strings.Split(path[1:], ".")
	rv := reflect.ValueOf(v)
	for _, field := range fields {
		rv = rv.FieldByName(field)
		if !rv.IsValid() {
			return nil
		}
	}
	return rv.Interface()
}

package main

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

type User struct {
	Name    string  `json:"name"`
	Profile Profile `json:"profile"`
}

type Profile struct {
	Email string `json:"email"`
	Phone string `json:"phone"`
}

func main() {
	jsonData := `{
		"name": "John Doe",
		"profile": {
			"email": "john.doe@example.com",
			"phone": "123-456-7890"
		}
	}`

	var user User
	if err := json.Unmarshal([]byte(jsonData), &user); err != nil {
		fmt.Println("Error unmarshalling JSON:", err)
		return
	}

	fmt.Println(getValueFromPath(user, ".name"))          // "John Doe"
	fmt.Println(getValueFromPath(user, ".profile"))       // {john.doe@example.com 123-456-7890}
	fmt.Println(getValueFromPath(user, ".profile.email")) // "john.doe@example.com"
	fmt.Println(getValueFromPath(user, ".profile.phone")) // "123-456-7890"
}

func getValueFromPath(v interface{}, path string) interface{} {
	fields := strings.Split(strings.TrimPrefix(path, "."), ".")
	rv := reflect.ValueOf(v)

	for _, field := range fields {
		rv = reflect.Indirect(rv)

		rt := rv.Type()
		found := false

		for i := 0; i < rt.NumField(); i++ {
			structField := rt.Field(i)
			jsonTag := structField.Tag.Get("json")

			if jsonTag == field {
				rv = rv.Field(i)
				found = true
				break
			}
		}

		if !found || !rv.IsValid() {
			return nil
		}
	}

	return rv.Interface()
}