type LoginForm struct {
    Username string `json:"username" validate:"required,min=3,max=32"`
    Password string `json:"password" validate:"required,min=6"`
}

func validateLoginForm(data LoginForm) map[string]string {
    validate := validator.New()
    errors := make(map[string]string)

    err := validate.Struct(data)
    if err != nil {
        for _, err := range err.(validator.ValidationErrors) {
            field := err.Field()
            tag := err.Tag()
            // 可以根据 tag 映射更友好的提示
            switch tag {
            case "required":
                errors[field] = "此字段为必填项"
            case "min":
                errors[field] = "输入内容长度不足"
            case "max":
                errors[field] = "输入内容过长"
            default:
                errors[field] = "校验不通过"
            }
        }
    }

    return errors
}

type ErrorResponse struct {
    Success bool                   `json:"success"`
    Message string                 `json:"message"`
    Errors  map[string]string      `json:"errors,omitempty"`
}

// 使用方式
if len(validationErrors) > 0 {
    c.JSON(http.StatusBadRequest, ErrorResponse{
        Success: false,
        Message: "数据校验失败",
        Errors:  validationErrors,
    })
    return
}

type UserForm struct {
    Email string `json:"email" validate:"required,email" msg:"请输入有效的邮箱地址"`
}