A mock "users" microservice in Go (Toy example)

main.go

package main

import (
	"encoding/json"
	"log"
	"net/http"
	"strings"
)

// User represents a user entity
type User struct {
	ID    int    `json:"id"`
	Name  string `json:"name"`
	Email string `json:"email"`
}

// UserService encapsulates business logic for users
type UserService struct {
	users []User
}

// NewUserService creates a new UserService with mock data
func NewUserService() *UserService {
	return &UserService{
		users: []User{
			{ID: 1, Name: "alice", Email: "alice@example.com"},
			{ID: 2, Name: "bob", Email: "bob@example.com"},
			{ID: 3, Name: "carol", Email: "carol@example.com"},
		},
	}
}

// GetUsersWithCapitalizedNames applies business logic to user data
func (s *UserService) GetUsersWithCapitalizedNames() []User {
	result := make([]User, len(s.users))
	for i, u := range s.users {
		u.Name = strings.Title(u.Name)
		result[i] = u
	}
	return result
}

// UserHandler encapsulates the HTTP layer
type UserHandler struct {
	service *UserService
}

// NewUserHandler creates a new UserHandler
func NewUserHandler(service *UserService) *UserHandler {
	return &UserHandler{service: service}
}

// ServeHTTP implements http.Handler for UserHandler
func (h *UserHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	userList := h.service.GetUsersWithCapitalizedNames()
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(userList)
}

func main() {
	userService := NewUserService()
	userHandler := NewUserHandler(userService)

	http.Handle("/users", userHandler)
	log.Println("Starting server on :8080...")
	log.Fatal(http.ListenAndServe(":8080", nil))
}