package main

import (
	"github.com/gin-gonic/gin"
)

func main() {
	g := gin.Default()
	g.GET("/", func(c *gin.Context) {
		var req struct {
			CreatedAt time.Time `form:"created_at" time_format:"unix"`
		}
		if err := c.ShouldBind(&req); err != nil {
			str := fmt.Sprintf("\n======err:%v\n", err)
			c.String(200, str)
			return
		}
		c.String(200, req.CreatedAt.String())
	})
	g.Run(":9000")
}

$ curl "http://localhost:9000/?created_at="
1970-01-01 08:00:00 +0800 CST

$ curl "http://localhost:9000/?created_at="
======err:strconv.ParseInt: parsing "": invalid syntax
0001-01-01 00:00:00 +0000 UTC