我如何在来自资源的 DataAnnotations 错误消息中使用 DRY（不要重复自己）

Question

这是我的代码

    [Required(ErrorMessageResourceType = typeof(DCC.RegistrationVMLiterals), ErrorMessageResourceName = "Required")]
    [RegularExpression("^[0-9]*$", ErrorMessageResourceType =typeof(DCC.RegistrationVMLiterals),ErrorMessageResourceName ="MustBeNumber")]
    [Display(Name = "BeneficiaryNo")]
    public long BeneficiaryNo { get; set; }

    [Required(ErrorMessageResourceType = typeof(DCC.RegistrationVMLiterals), ErrorMessageResourceName = "Required")]
    [RegularExpression("^[a-zA-z]*$",ErrorMessage ="must only be letters")]
    [Display(Name = "FullName")]
    public string FullName { get; set; }
    [Required(ErrorMessageResourceType = typeof(DCC.RegistrationVMLiterals), ErrorMessageResourceName = "Required")]
    [Display(Name = "GenderID")]
    public int GenderID { get; set; }`

Answer 1

试试这个，还没有测试过，但应该可以：

[AttributeUsage(AttributeTargets.Class)]
public class AggregatedRequiredAttribute: ValidationAttribute
{
    private readonly string[] _propertiesToValidate;
    private readonly string message = Resources.ValRequired;

    public AggregatedRequiredAttribute(params string[] propertiesToValidate)
    {
        if (propertiesToValidate == null || !propertiesToValidate.Any()) throw new ArgumentException(nameof(propertiesToValidate));
        _propertiesToValidate = propertiesToValidate;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        if (!validationContext.ObjectType.GetMember(validationContext.MemberName).Any())
            throw new InvalidOperationException("Current type does not contain such property.");

        if (!_propertiesToValidate.Contains(validationContext.MemberName))
            return ValidationResult.Success;

        var defaultRequired = new RequiredAttribute() {ErrorMessage = message};
        return defaultRequired.IsValid(value) ? ValidationResult.Success : new ValidationResult(message);
    }
}

然后你可以像这样使用它（来自默认 MVC 模板的 ViewModel）：

[AggregatedRequired("Email","Password")]
public class RegisterViewModel
{
    [EmailAddress]
    [Display(Name = "Email")]
    public string Email { get; set; }

    [StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 6)]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    public string Password { get; set; }

    [DataType(DataType.Password)]
    [Display(Name = "Confirm password")]
    [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
    public string ConfirmPassword { get; set; }
}

注意，我只使用了一次错误消息字符串，您也可以在错误消息中使用一些字母并将其动态替换为正在验证的属性的实际名称。

更新

我不确定第一个 if 语句，你应该测试一下。

更新 2

另外我想我用错了IsValid方法，但思路本身很清楚。

Answer 2

我认为你误解了这个概念或 DRY。

你在重复的事实

[Required(ErrorMessageResourceType = typeof(DCC.RegistrationVMLiterals), ErrorMessageResourceName = "Required")]
[RegularExpression("^[0-9]*$", ErrorMessageResourceType =typeof(DCC.RegistrationVMLiterals),ErrorMessageResourceName ="MustBeNumber")]

在此上下文中不是重复。

重复会是这样的：

public void DoSomething()
{
    string myString = "ABC";
    Print(myString);
    Do something...
}

public void DoSomething1()
{
    string myString = "ABC";
    Print(myString);
    Do something different...
}

对此的 DRY 响应是

public void DoSomething()
{
    Print(getString());
    Do something...
}

public void DoSomething1()
{
    Print(getString());
    Do something different...
}

public string getString()
{
    return "ABC";
}

我如何在来自资源的 DataAnnotations 错误消息中使用 DRY（不要重复自己）

How could i use DRY(don't repeat yourself) in DataAnnotations Error messages form Resourse

c#

asp.net-mvc

data-annotations