APIフレームワークとしてechoを使い、配列と構造体での吐き出し方法

main.go

package main

import (
	"github.com/labstack/echo"
	"github.com/labstack/echo/middleware"
	
	"hoge/signup"
)

func main() {
	e := echo.New()

	e.Use(middleware.Logger())
	e.Use(middleware.Recover())

	/* routing */
	e.GET("/", Index())
	e.POST("/signup/array", signup.SignupArray())
	e.POST("/signup/struct", signup.SignupStruct())

	e.Logger.Fatal(e.Start(":3000"))
}

func Index() echo.HandlerFunc {
	return func(c echo.Context) error {
		jsonMap := map[string]string{
			"hoge": "this is your domain",
		}

		return c.JSON(200, jsonMap)
	}
}

signup.go

package signup

import (
	"github.com/labstack/echo"
	
	"regexp"
)

func SignupArray() echo.HandlerFunc {
	return func(c echo.Context) error {
		username := c.FormValue("username")
		email := c.FormValue("email")
		password := c.FormValue("password")

		var jsonMap map[string]interface{} = make(map[string]interface{})
		var errors = make([]map[string]interface{}, 0)
		var httpStatus = 200

		/* username */
		if username == "" {
			errors = append(errors, map[string]interface{}{
				"status":  400,
				"param":   "username",
				"message": "invalid",
			})
		}

		/* email */
		if !regexp.MustCompile(`^.+@.$`).MatchString(email) {
			errors = append(errors, map[string]interface{}{
				"status":  400,
				"param":   "email",
				"message": "invalid",
			})
		}

		/* password */
		if !regexp.MustCompile(`^[0-9a-zA-Z]{8,}$`).MatchString(password) {
			errors = append(errors, map[string]interface{}{
				"status":  400,
				"param":   "password",
				"message": "invalid",
			})
		}

		/* jsonMap */
		if len(errors) > 0 {
			jsonMap["errors"] = errors
			httpStatus = 400
		} else {
			jsonMap = map[string]interface{}{
				"links": map[string]string{
					"self": "/signup",
				},
				"data": nil,
			}
		}

		return c.JSON(httpStatus, jsonMap)
	}
}




type Result struct {
	Errors []Error `json:"errors"`
	Links  Links   `json:"links"`
	Data   Data    `json:"data"`
}

type Result_Success struct {
	Links Links `json:"links"`
	Data  Data  `json:"data"`
}

type Result_Error struct {
	Errors []Error `json:"errors"`
}

type Error struct {
	Status  int    `json:"status"`
	Param   string `json:"param"`
	Message string `json:"message"`
}

type Links struct {
	Self string      `json:"self"`
	Next interface{} `json:"next"`
	Prev interface{} `json:"prev"`
}

type Data interface{}

func SignupStruct() echo.HandlerFunc {
	return func(c echo.Context) error {
		username := c.FormValue("username")
		email := c.FormValue("email")
		password := c.FormValue("password")

		var httpStatus = 200
		var errors = make([]Error, 0)

		/* username */
		if username == "" {
			errors = append(errors, Error{
				Status:  400,
				Param:   "username",
				Message: "invalid",
			})
		}

		/* email */
		if !regexp.MustCompile(`^.+@.$`).MatchString(email) {
			errors = append(errors, Error{
				Status:  400,
				Param:   "email",
				Message: "invalid",
			})
		}

		/* password */
		if !regexp.MustCompile(`^[0-9a-zA-Z]{8,}$`).MatchString(password) {
			errors = append(errors, Error{
				Status:  400,
				Param:   "password",
				Message: "invalid",
			})
		}

		// 構造体のフィールド名は削除できないので、
		// 構造体でSignupArrayと同じことをしたいならば、
		// 下記のように構造体自体を分けてあげる必要があり
		if len(errors) > 0 {
			res := Result_Error{}

			res.Errors = errors

			return c.JSON(httpStatus, res)
		} else {
			res := Result_Success{}

			res.Links = Links{
				Self: "/signup",
			}
			res.Data = nil

			// 構造体を渡してもecho側でMarshalしてくれる
			return c.JSON(httpStatus, res)
		}
	}
}