Converting escaped forms of unicode characters in JSON into unescaped UTF-8 characters.

unescape_unicode_sequences_in_json.go

package main

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

func _UnescapeUnicodeCharactersInJSON(_jsonRaw json.RawMessage) (json.RawMessage, error) {
	str, err := strconv.Unquote(strings.Replace(strconv.Quote(string(_jsonRaw)), `\\u`, `\u`, -1))
	if err != nil {
		return nil, err
	}
	return []byte(str), nil
}

func main() {
	// Both are valid JSON.
	var jsonRawEscaped json.RawMessage   // json raw with escaped unicode chars
	var jsonRawUnescaped json.RawMessage // json raw with unescaped unicode chars

	// '\u263a' == '☺'
	jsonRawEscaped = []byte(`{"HelloWorld": "\uC548\uB155, \uC138\uC0C1(\u4E16\u4E0A). \u263a"}`) // "\\u263a"
	jsonRawUnescaped, _ = _UnescapeUnicodeCharactersInJSON(jsonRawEscaped)                        // "☺"

	fmt.Println(string(jsonRawEscaped))   // {"HelloWorld": "\uC548\uB155, \uC138\uC0C1(\u4E16\u4E0A). \u263a"}
	fmt.Println(string(jsonRawUnescaped)) // {"HelloWorld": "안녕, 세상(世上). ☺"}
}