binding:extended time.Time type, support Unix time

[guonaihong]

I sometimes use createTime (unix time) as the key for data segmentation. A common usage is that Service A is responsible for generating creatTime. Service B routes to the corresponding database table based on createTime in the data.
It is found that gin does not currently support binding of unix time to time.Time type.

Pseudo code is as follows

package main

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

type shareTime struct {
        CreateTime time.Time `form:"createTime" time_format:"unixNano"`
        UnixTime   time.Time `form:"unixTime" time_format:"unix"`
}

func main() {
        r := gin.Default()
        unix := r.Group("/unix")

        testCT := time.Date(2019, 7, 6, 16, 0, 33, 123, time.Local)
        fmt.Printf("%d\n", testCT.UnixNano())

        testUT := time.Date(2019, 7, 6, 16, 0, 33, 0, time.Local)
        fmt.Printf("%d\n", testUT.Unix())

        unix.GET("/nano", func(c *gin.Context) {
                s := shareTime{}

                c.ShouldBindQuery(&s)

                if !testCT.Equal(s.CreateTime) {
                        c.String(500, "want %d got %d", testCT.UnixNano(), s.CreateTime)
                        return
                }

                c.JSON(200, s)
        })

        unix.GET("/sec", func(c *gin.Context) {
                s := shareTime{}

                c.ShouldBindQuery(&s)

                if !testUT.Equal(s.UnixTime) {
                        c.String(500, "want %d got %d", testCT.Unix(), s.UnixTime)
                        return
                }

                c.JSON(200, s)

        })

        r.Run()
}

// client
//
// curl -X GET "127.0.0.1:8080/unix/sec?unixTime=1562400033"
//   {"CreateTime":"0001-01-01T00:00:00Z","UnixTime":"2019-07-06T16:00:33+08:00"}

// curl -X GET "127.0.0.1:8080/unix/nano?createTime=1562400033000000123"
//   {"CreateTime":"2019-07-06T16:00:33.000000123+08:00","UnixTime":"0001-01-01T00:00:00Z"}

[IsQiao]

the feature can't bind requrest json body property. any solution about it?