go 结构体转 json 时, 日期类型转换

package main

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

type DateTime time.Time

func (d DateTime) MarshalJSON() ([]byte, error) {
	dateTime := fmt.Sprintf("%q", time.Time(d).Format("2006-01-02 15:04:05"))
	return []byte(dateTime), nil
}

type Tom struct {
	Name     string   `json:"name"`
	Age      int      `json:"age"`
	Birthday DateTime `json:"birthday"`
}

func main() {
	tom := Tom{
		Name:     "tom",
		Age:      25,
		Birthday: DateTime(time.Now()),
	}
	bytes, err := json.Marshal(tom)
	if err == nil {
		fmt.Println(string(bytes))
	}
}

{"name":"tom","age":25,"birthday":"2021-06-18 15:04:03"}