Go Development Standards

Project Layout

project/
├── cmd/                  # Entry point per binary
│   └── server/
│       └── main.go
├── internal/             # Private code
│   ├── domain/           # Entity, use case interface
│   ├── application/      # Service, DTO
│   ├── infrastructure/   # Handler, repo, middleware
│   └── config/           # Config loader
├── pkg/                  # Shared, reusable code
├── migrations/           # DB migrations (atlas, goose)
├── tests/                # Integration tests
├── Makefile
├── go.mod
└── go.sum

Dependency Injection

Gunakan uber-go/fx untuk wiring otomatis.

func main() {
    fx.New(
        config.Module,
        database.Module,
        modules.UserModule,
        fx.Invoke(func(*server.Server) {}),
    ).Run()
}

API Handler (Chi)

func (h *Handler) CreateUser(w http.ResponseWriter, r *http.Request) {
    var req CreateUserRequest
    if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
        respond.Error(w, http.StatusBadRequest, "invalid body")
        return
    }

    user, err := h.service.Create(r.Context(), req)
    if err != nil {
        respond.Error(w, http.StatusInternalServerError, err.Error())
        return
    }

    respond.OK(w, user)
}

Error Handling

// Return early
if err != nil {
    return fmt.Errorf("failed to create user: %w", err)
}

// Wrap context
return fmt.Errorf("user %s: %w", userID, ErrNotFound)

Testing

• Unit test: go test ./internal/...
• Integration test: go test ./tests/... -tags integration
• Coverage target: > 70%

func TestCreateUser(t *testing.T) {
    repo := newMockUserRepo()
    svc := NewUserService(repo)

    user, err := svc.Create(ctx, CreateUserRequest{Name: "Khoirul"})
    assert.NoError(t, err)
    assert.Equal(t, "Khoirul", user.Name)
}

Tools

Orm / Query Builder

• Ent (Facebook): Type-safe, generated code
• GORM: Prototyping dan rapid dev
• SQLx: Raw SQL dengan scanning
• Raw SQL: Untuk query kompleks / performance critical

Config

Gunakan struct tag + environment variables:

type Config struct {
    Port     int    `env:"PORT,default=8080"`
    DBHost   string `env:"DB_HOST,required"`
    LogLevel string `env:"LOG_LEVEL,default=info"`
}