asp.net-mvc - 在 EF 伙伴类上使用自定义属性 (AttributeTargets.Class) 进行数据验证

Question

我有一个具有以下属性的 Entity Framework 生成的类:

public DateTime LaunchDate;
public DateTime ExpirationDate;

我需要强制执行 ExpirationDate > LaunchDate。

我正在使用各种帖子中描述的好友类。我正在将自定义验证属性(在属性上)应用到同一好友类中的其他属性，这些属性正在工作。

因为我需要比较两个属性，所以我直接在类 (AttributeTargets.Class) 上使用属性

这是我的自定义验证属性:

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public class PropertyMustBeGreaterThanAttribute : ValidationAttribute
{
    private const string _defaultErrorMessage = "'{0}' must be greater than '{1}'!";

    public PropertyMustBeGreaterThanAttribute(string property, string greaterThan)
        : base(_defaultErrorMessage)
    {
        GreaterThan = greaterThan;
        Property = property;
    }

    public string Property { get; private set; }
    public string GreaterThan { get; private set; }

    public override string FormatErrorMessage(string name)
    {
        return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString,
            GreaterThan, Property);
    }

    public override bool IsValid(object value)
    {
        PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value);
        IComparable greaterThan = properties.Find(GreaterThan, true /* ignoreCase */).GetValue(value) as IComparable;
        IComparable property = properties.Find(Property, true /* ignoreCase */).GetValue(value) as IComparable;
        return greaterThan.CompareTo(property) > 0;
    }
}

首先我不确定我需要将属性应用到哪个类:

[MetadataType(typeof(PromotionValidation))]
[PropertyMustBeGreaterThanAttribute("RetailPrice")] // apply it here
public partial class Promotion
{
    [PropertyMustBeGreaterThanAttribute("ExpirationDate", "LaunchDate")] // or here ???
    public class PromotionValidation
    {

其次，它不起作用，我不知道为什么!!!我试过为这两个类添加属性。命中构造函数中的断点 (PropertyMustBeGreaterThanAttribute)，但从未调用 IsValid。

已经把我的头发拔出来了....

谢谢!

Answer 1

通过实现 TypeID 让它工作。我将属性分配给部分类:

    [MetadataType(typeof(PromotionValidation))]
    [PropertyMustBeGreaterThanAttribute("RetailPrice", "DiscountedPrice")]
    [PropertyMustBeGreaterThanAttribute("ExpirationDate", "LaunchDate")]
    [PropertyMustBeGreaterThanAttribute("ClaimDeadline", "ExpirationDate")]
    public partial class Promotion
    {
... 

以下是 list ，以备不时之需:

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public class PropertyMustBeGreaterThanAttribute : ValidationAttribute
{
    private const string _defaultErrorMessage = "'{1}' must be greater than '{0}'!";
    private readonly object _typeId = new object();

    public PropertyMustBeGreaterThanAttribute(string property, string greaterThan)
        : base(_defaultErrorMessage)
    {
        GreaterThan = greaterThan;
        Property = property;
    }

    public string Property { get; private set; }
    public string GreaterThan { get; private set; }

    public override string FormatErrorMessage(string name)
    {
        return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString,
            GreaterThan, Property);
    }

    public override bool IsValid(object value)
    {
        PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value);
        IComparable greaterThan = properties.Find(GreaterThan, true /* ignoreCase */).GetValue(value) as IComparable;
        IComparable property = properties.Find(Property, true /* ignoreCase */).GetValue(value) as IComparable;
        return greaterThan.CompareTo(property) > 0;
    }

    public override object TypeId
    {
        get
        {
            return _typeId;
        }
    }
}