c# - 在 MetadataProvider 中获取多个相同类型的属性

Question

我有一个属性，它有 AllowMultiple:

[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
public class AllowedDeviceTypesAttribute : System.Attribute
{
    //...
}

我在我的属性(property)上多次使用它:

[AllowedDeviceTypes(DeviceTypes.StaticRegister)]
[AllowedDeviceTypes(DeviceTypes.MobileRegister)]
public int ClientNr { get; set; }

我有一个自定义模型元数据提供程序:

public class ExtendedModelMetadataProvider : DataAnnotationsModelMetadataProvider
{
    protected override ModelMetadata CreateMetadata(IEnumerable<System.Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName)
    {
        var attributeList = attributes as IList<System.Attribute> ?? attributes.ToList();
        var data = base.CreateMetadata(attributeList, containerType, modelAccessor, modelType, propertyName);
        //...
        var allowedDeviceTypesAttributes = attributeList.Where(a => typeof(AllowedDeviceTypesAttribute) == a.GetType()).ToList();
        if (allowedDeviceTypesAttributes.Count > 0)
        {
            var allowedDeviceTypes = allowedDeviceTypesAttributes.Cast<AllowedDeviceTypesAttribute>().Select(e => e.AllowedDeviceType).ToList();
            data.AdditionalValues.Add(AllowedDeviceTypesAttribute.AdditionalMetaDataValue, allowedDeviceTypes);
        }

        return data;
    }
}

我的问题是，我在 attributes 中总是只有一个 AllowedDeviceTypesAttribute:

如何获得这两个属性？

[AllowedDeviceTypes(DeviceTypes.StaticRegister)]
[AllowedDeviceTypes(DeviceTypes.MobileRegister)]

Answer 1

为了让它工作，我们需要覆盖 TypeId 属性:

[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
public class AllowedDeviceTypesAttribute : System.Attribute
{
    //...
    public override object TypeId
    {
        get
        {
            return this;
        }
    }
}