Asp.Net MVC 验证 - 依赖字段

Question

我目前正在尝试通过 MVC 验证工作，并且遇到了一些问题，即根据另一个字段的值需要一个字段。下面是一个示例（我还没有弄清楚） - 如果 PaymentMethod == "Cheque"，则应该需要 ChequeName，否则可以通过。

[Required(ErrorMessage = "Payment Method must be selected")]
public override string PaymentMethod
{ get; set; }

[Required(ErrorMessage = "ChequeName is required")]
public override string ChequeName
{ get; set; }

我将 System.ComponentModel.DataAnnotations 用于 [Required]，并且还扩展了 ValidationAttribute 以尝试使其正常工作，但我无法通过变量进行验证（下面的扩展）

public class JEPaymentDetailRequired : ValidationAttribute 
{
    public string PaymentSelected { get; set; }
    public string PaymentType { get; set; }

    public override bool IsValid(object value)
    {
        if (PaymentSelected != PaymentType)
            return true;
        var stringDetail = (string) value;
        if (stringDetail.Length == 0)
            return false;
        return true;
    }
}

实施：

[JEPaymentDetailRequired(PaymentSelected = PaymentMethod, PaymentType = "Cheque", ErrorMessage = "Cheque name must be completed when payment type of cheque")]

有没有人有过这种验证的经验？将其写入控制器会更好吗？

感谢您的帮助。

Answer 1

如果除了服务器上的模型验证之外还需要客户端验证，我认为最好的方法是自定义验证属性（如 Jaroslaw 建议的那样）。我在这里包括了我使用的来源。

自定义属性：

public class RequiredIfAttribute : DependentPropertyAttribute
{
    private readonly RequiredAttribute innerAttribute = new RequiredAttribute();

    public object TargetValue { get; set; }


    public RequiredIfAttribute(string dependentProperty, object targetValue) : base(dependentProperty)
    {
        TargetValue = targetValue;
    }


    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        // get a reference to the property this validation depends upon
        var containerType = validationContext.ObjectInstance.GetType();
        var field = containerType.GetProperty(DependentProperty);

        if (field != null)
        {
            // get the value of the dependent property
            var dependentvalue = field.GetValue(validationContext.ObjectInstance, null);

            // compare the value against the target value
            if ((dependentvalue == null && TargetValue == null) ||
                (dependentvalue != null && dependentvalue.Equals(TargetValue)))
            {
                // match => means we should try validating this field
                if (!innerAttribute.IsValid(value))
                    // validation failed - return an error
                    return new ValidationResult(ErrorMessage, new[] { validationContext.MemberName });
            }
        }

        return ValidationResult.Success;
    }

    public override IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule
                       {
                           ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
                           ValidationType = "requiredif"
                       };

        var depProp = BuildDependentPropertyId(DependentProperty, metadata, context as ViewContext);

        // find the value on the control we depend on;
        // if it's a bool, format it javascript style 
        // (the default is True or False!)
        var targetValue = (TargetValue ?? "").ToString();
        if (TargetValue != null)
            if (TargetValue is bool)
                targetValue = targetValue.ToLower();

        rule.ValidationParameters.Add("dependentproperty", depProp);
        rule.ValidationParameters.Add("targetvalue", targetValue);

        yield return rule;
    }
}

Jquery 验证扩展：

$.validator.unobtrusive.adapters.add('requiredif', ['dependentproperty', 'targetvalue'], function (options) {
    options.rules['requiredif'] = {
        dependentproperty: options.params['dependentproperty'],
        targetvalue: options.params['targetvalue']
    };
    options.messages['requiredif'] = options.message;
});

$.validator.addMethod('requiredif',
    function (value, element, parameters) {
        var id = '#' + parameters['dependentproperty'];

        // get the target value (as a string, 
        // as that's what actual value will be)
        var targetvalue = parameters['targetvalue'];
        targetvalue = (targetvalue == null ? '' : targetvalue).toString();

        // get the actual value of the target control
        var actualvalue = getControlValue(id);

        // if the condition is true, reuse the existing 
        // required field validator functionality
        if (targetvalue === actualvalue) {
            return $.validator.methods.required.call(this, value, element, parameters);
        }

        return true;
    }
);

用属性装饰一个属性：

[Required]
public bool IsEmailGiftCertificate { get; set; }

[RequiredIf("IsEmailGiftCertificate", true, ErrorMessage = "Please provide Your Email.")]
public string YourEmail { get; set; }

Answer 2

只需使用 Codeplex 上提供的 Foolproof 验证库： https://foolproof.codeplex.com/

它支持以下“requiredif”验证属性/装饰：

[RequiredIf]
[RequiredIfNot]
[RequiredIfTrue]
[RequiredIfFalse]
[RequiredIfEmpty]
[RequiredIfNotEmpty]
[RequiredIfRegExMatch]
[RequiredIfNotRegExMatch]

上手很简单：

1. 从提供的链接下载包
2. 添加对包含的 .dll 文件的引用
3. 导入包含的 javascript 文件
4. 确保您的视图从其 HTML 中引用包含的 javascript 文件，以实现不显眼的 javascript 和 jquery 验证。

Answer 3

我会在模型中而不是控制器中编写验证逻辑。控制器应该只处理视图和模型之间的交互。由于它是需要验证的模型，我认为它被广泛认为是验证逻辑的地方。

对于依赖于另一个属性或字段的值的验证，我（不幸的是）看不到如何完全避免在模型中为此编写一些代码，例如 Wrox ASP.NET MVC 书中所示，排序比如：

public bool IsValid
{
  get 
  {
    SetRuleViolations();
    return (RuleViolations.Count == 0); 
  }
}

public void SetRuleViolations()
{
  if (this.PaymentMethod == "Cheque" && String.IsNullOrEmpty(this.ChequeName))
  {
    RuleViolations.Add("Cheque name is required", "ChequeName");
  }
}

以声明方式进行所有验证会很棒。我相信你可以创建一个RequiredDependentAttribute，但这只会处理这种类型的逻辑。稍微复杂一点的东西需要另一个非常具体的属性，等等，这很快就会变得疯狂。

Answer 4

你的问题可以通过conditional validation attribute的用法相对简单地解决，例如

[RequiredIf("PaymentMethod == 'Cheque'")]
public string ChequeName { get; set; }