How to parse string to mail.Address

[apuatcfbd]

I am trying to parse the following

type NewEmail struct {
	From        mail.Address                 `form:"from"`
	// ...
}

with

// In handler
if err := c.Bind(dtoPtr); err != nil { // dtoPtr is *NewEmail
	errResponse = c.JSON(http.StatusBadRequest, Res(ResData{
		Msg: "Review your input",
		D:   err, // here's the error
	}))
	return
}

Getting following error unknown type

{
  "d": {
    "message": "unknown type"
  },
  "msg": "Review your input",
  "status": false
}

I've checked that it works if I make NewEmail structs From field to string from mail.Address. It is beneficial for me if I can parse to mail.Address based on my use case. How this can be done?

[aldas]

Could you provide how mail.Address is declared? Is is struct or alias or ?

[apuatcfbd]

The type mail.Address is from net/mail of StdLib
That struct looks like the following

type Address struct {
    Name    string
    Address string
}

Echo version github.com/labstack/echo/v4 v4.13.3

[aldas]

This

package main

import (
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"log/slog"
	"net/http"
	"net/mail"
)

func main() {
	e := echo.New()
	e.Use(middleware.Logger())

	e.POST("/", func(c echo.Context) error {
		type NewEmail struct {
			From mail.Address `form:"from"`
		}
		dto := &NewEmail{}
		if err := c.Bind(dto); err != nil { // dto is *NewEmail
			return c.JSON(http.StatusBadRequest, map[string]interface{}{"error": err.Error()})
		}
		return c.JSON(http.StatusOK, dto)
	})

	if err := e.Start(":8080"); err != nil {
		slog.Error("failed to start server")
	}
}

does not work because you can only bind forms to (struct) fields that are explicitly marked with struct tags. But currently the target is struct with additional fields - this is not supported.

You could create your own address type and add tags

	e.POST("/", func(c echo.Context) error {
		type Address struct {
			Name    string `form:"name"`
			Address string `form:"address"`
		}

		type NewEmail struct {
			From Address
		}
		dto := &NewEmail{}
		if err := c.Bind(dto); err != nil { // dto is *NewEmail
			return c.JSON(http.StatusBadRequest, map[string]interface{}{"error": err.Error()})
		}
		return c.JSON(http.StatusOK, dto)
	})

test with

curl --form name=testName --form address=testAddress http://localhost:8080/

[aldas]

note:
curl -H "Content-Type: application/json" --data '{"from":{"name":"test","address":"address"}}' http://localhost:8080/ would work with

	e.POST("/", func(c echo.Context) error {
		type NewEmail struct {
			From mail.Address
		}
		dto := &NewEmail{}
		if err := c.Bind(dto); err != nil { // dto is *NewEmail
			return c.JSON(http.StatusBadRequest, map[string]interface{}{"error": err.Error()})
		}
		return c.JSON(http.StatusOK, dto)
	})

but this is because standard library JSON unmarshalling supports this