使用EF伙伴类上的自定义属性(AttributeTargets.Class)进行数据验证

Question

我有一个Entity Framework生成的类,具有以下属性:

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.我将自定义验证属性(在属性上)应用于同一伙伴类中的其他属性,这些属性正在运行.

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

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于哪个类:

[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!我已经尝试为这两个类添加属性.命中构造函数中的断点(PropertyMustBeGreaterThanAttribute),但从不调用IsValid.

拉出我的头发......

谢谢!

Answer 1

通过实现TypeID来实现它.我将属性分配给了分部类:

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

如果有人需要,这是列表:

[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;
        }
    }
}