如何使用Golang实现Web表单数据绑定

func handler(w http.ResponseWriter, r *http.Request) {
    r.ParseForm()

    // 获取表单字段
    username := r.Form.Get("username")
    email := r.Form.Get("email")

    fmt.Fprintf(w, "用户名: %s, 邮箱: %s", username, email)
}

type User struct {
    Username string `form:"username"`
    Email    string `form:"email"`
}

func bindForm(r *http.Request, dst interface{}) error {
    if err := r.ParseForm(); err != nil {
        return err
    }

    v := reflect.ValueOf(dst).Elem()
    t := v.Type()

    for i := 0; i < v.NumField(); i++ {
        field := v.Field(i)
        tag := t.Field(i).Tag.Get("form")
        if tag == "" || tag == "-" {
            continue
        }
        if field.CanSet() {
            if value := r.Form.Get(tag); value != "" {
                field.SetString(value)
            }
        }
    }
    return nil
}

var user User
if err := bindForm(r, &user); err != nil {
    http.Error(w, err.Error(), 400)
    return
}

type LoginForm struct {
    Username string `form:"username" binding:"required"`
    Password string `form:"password" binding:"required"`
}

func loginHandler(c *gin.Context) {
    var form LoginForm
    if err := c.ShouldBind(&form); err != nil {
        c.JSON(400, gin.H{"error": err.Error()})
        return
    }
    c.JSON(200, gin.H{"message": "登录成功"})
}

r.ParseMultipartForm(10 << 20) // 最大10MB
file, handler, err := r.FormFile("avatar")
if err != nil {
    // 处理错误
    return
}
defer file.Close()