Example of custom unmarshal of JSON in golang

custom_json_unmarshal.go

package main

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

type To []string

type Message struct {
  From string `"json:from"`
  To To `"json:to"`
  Message string `"json:message"`
}

func (c *To) UnmarshalJSON(data []byte) error {
	var nums interface{}
	err := json.Unmarshal(data, &nums)
	if err != nil {
		return err
	}

	items := reflect.ValueOf(nums)
	switch items.Kind() {
	case reflect.String:
		*c = append(*c, items.String())

	case reflect.Slice:
		*c = make(To, 0, items.Len())
		for i := 0; i < items.Len(); i++ {
			item := items.Index(i)
			switch item.Kind() {
			case reflect.String:
				*c = append(*c, item.String())
			case reflect.Interface:
				*c = append(*c, item.Interface().(string))
			}
		}
	}
	return nil
}

can u also add example of json?

can u also add example of json?

Sure, it is very simple:

//...
func main() {
  jsonMsg := []byte(`{ "from": "me", "to": "you",  "message": "hello you" }`)
  var message Message

  err := json.Unmarshal(jsonMsg, &message)
  
  fmt.Printf("message: %#v | err: %v", message, err)

 // > message: main.Message{From:"me", To:main.To{"you"}, Message:"hello you"}
}

can u also add example of json?

Sure, it is very simple:

//...
func main() {
  jsonMsg := []byte(`{ "from": "me", "to": "you",  "message": "hello you" }`)
  var message Message

  err := json.Unmarshal(jsonMsg, &message)
  
  fmt.Printf("message: %#v | err: %v", message, err)

 // > message: main.Message{From:"me", To:main.To{"you"}, Message:"hello you"}
}

thank you)