详解Go语言如何对数据库进行CRUD操作

// NOTE: storage.go
// 存储文件接口
type Storage interface {
    Save(data []byte) (string, error)
}
// 开发时候使用本地存储
type localStorage struct {
    config *struct{ base string }
}
func NewLocalStorage(cfg struct{ base string }) *localStorage {
    return &localStorage{config: &cfg}
}
func (store localStorage) Save(data []byte) (string, error) {
    return "http://127.0.0.1/" + store.config.base + "/a.png", nil
}
// 生产使用oss存储
type ossStorage struct{}
func NewOSSStorage() *ossStorage {
    return &ossStorage{}
}
func (store ossStorage) Save(data []byte) (string, error) {
    return "https://abc.com/oss/a.png", nil
}
// NOTE: upload.go
// 保存文件
func saveFile(store Storage) {
    var data []byte // 伪代码
    url, _ := store.Save(data)
    fmt.Println(url)
}
func main() {
    var store Storage
    if os.Getenv("ENV") == "prod" {
        store = NewOSSStorage()
    } else {
        store = NewLocalStorage(struct{ base string }{base: "/static"})
	}
    saveFile(store)
}

type Repository struct {
    DB *sql.DB
}
func NewRepository(db *sql.DB) *Repository {
    return &Repository{DB: db}
}
func (repo *Repository) Insert() {
    // do some thing
}
func (repo *Repository) Update() {
    // do some thing
}
type Service struct {
    Repo Repository
}
func NewService(db *sql.DB) *Service {
    return &Service{
        Repo: *NewRepository(db),
    }
}
func main() {
    // 假设是真实的链接 &sql.DB{}
    srv := NewService(&sql.DB{})
    srv.Repo.Insert()
    srv.Repo.Update()
}

type Repository interface {
	Insert()
	Update()
}

type repository struct {
	DB *sql.DB
}

func NewRepository(db *sql.DB) *repository {
	return &repository{DB: db}
}

func (repo *repository) Insert() {
	// do some thing
}

func (repo *repository) Update() {
	// do some thing
}

type Service struct {
	Repo Repository
}

func NewService(r Repository) *Service {
	return &Service{
		Repo: r,
	}
}

func main() {
	// 假设是真实的链接 &sql.DB{}
	r := NewRepository(&sql.DB{})
	srv := NewService(r)
	srv.Repo.Insert()
	srv.Repo.Update()
}

// 第三方的接口定义
type Worker interface {
    Context() context.Context
    DoSomeThing()
    // ...
}

type wrapWorker interface {
    Worker
    SetContext(context.Context)
}
type wrap struct {
    Worker
    ctx context.Context
}

func newWrap(w Worker) wrapWorker {
    return &wrap{
        w,
        w.Context(),
    }
}
func (wp *wrap) SetContext(ctx context.Context) {
    wp.ctx = ctx
}

func (wp wrap) Context() context.Context {
    return wp.ctx
}

type contextKey string

func work(w Worker) {
    wp := newWrap(w)
    ctx := context.WithValue(w.Context(), contextKey("greet"), "Hello")
    wp.SetContext(ctx)

    next(wp)
}

func next(w Worker) {
    v := w.Context().Value(contextKey("greet"))
    fmt.Printf("-> %v \n", v)
    w.DoSomeThing()
}

type person string

func (person) Context() context.Context {
    return context.Background()
}
func (p person) DoSomeThing() {
    fmt.Println(string(p), "吃饭睡觉打代码～")
}

func main() {
    var p person = "张三"
    work(p)
}