How do I bind a date string to a struct? - go

Question

type TestModel struct {
Date time.Time `json:"date" form:"date" gorm:"index"`
gorm.Model
}
i'm using echo framwork, and
I have a struct like the one above, and I get string data like '2021-09-27' , how can I bind it to the struct?
func CreateDiary(c echo.Context) error {
var getData model.TestModel
if err := (&echo.DefaultBinder{}).BindBody(c, &getData); err != nil {
fmt.Print(err.Error())
}
return c.JSON(200, getData)
}
When I code like this, I get the following error:
code=400, message=parsing time "2021-09-27" as "2006-01-02T15:04:05Z07:00": cannot parse "" as "T", internal=parsing time "2021-09-27" as "2006-01-02T15:04:05Z07:00": cannot parse "" as "T"
I'm a golang beginner, can you show me a simple example??, please.
i'm using echo framwork

Answer 1

Type CustomTime time.Time
func (ct *CustomTime) UnmarshalParam(param string) error {
t, err := time.Parse(`2006-01-02`, param)
if err != nil {
return err
}
*ct = CustomTime(t)
return nil
}
ref: https://github.com/labstack/echo/issues/1571

Answer 2

Here is list of available tags used in echo. If you want to parse from body, then use json
query - source is request query parameters.
param - source is route path parameter.
header - source is header parameter.
form - source is form. Values are taken from query and request body. Uses Go standard library form parsing.
json - source is request body. Uses Go json package for unmarshalling.
xml - source is request body. Uses Go xml package for unmarshalling.
You need to wrap time.Time into custom struct and then implement json.Marshaler and json.Unmarshaler interfaces
Example
package main
import (
"fmt"
"strings"
"time"
"github.com/labstack/echo/v4"
)
type CustomTime struct {
time.Time
}
type TestModel struct {
Date CustomTime `json:"date"`
}
func (t CustomTime) MarshalJSON() ([]byte, error) {
date := t.Time.Format("2006-01-02")
date = fmt.Sprintf(`"%s"`, date)
return []byte(date), nil
}
func (t *CustomTime) UnmarshalJSON(b []byte) (err error) {
s := strings.Trim(string(b), "\"")
date, err := time.Parse("2006-01-02", s)
if err != nil {
return err
}
t.Time = date
return
}
func main() {
e := echo.New()
e.POST("/test", CreateDiary)
e.Logger.Fatal(e.Start(":1323"))
}
func CreateDiary(c echo.Context) error {
var getData TestModel
if err := (&echo.DefaultBinder{}).BindBody(c, &getData); err != nil {
fmt.Print(err.Error())
}
return c.JSON(200, getData)
}
test
curl -X POST http://localhost:1323/test -H 'Content-Type: application/json' -d '{"date":"2021-09-27"}'