C# Buddy Classes / Meta Data and Reflection

.net, attributes, c#, reflection

Solution

the solution is to use `GetCustomAttributes` to get MetaData types and check the properties on those as well...

Type t = typeof(MyClass);
PropertyInfo pi = t.GetProperty(PropertyName);  
bool isReadOnly = ReadOnlyAttribute.IsDefined(pi, typeof(ReadOnlyAttribute));

if (!isReadOnly)
{
    //check for meta data class.
    MetadataTypeAttribute[] metaAttr = (MetadataTypeAttribute[])t.GetCustomAttributes(typeof(MetadataTypeAttribute),true);

    if (metaAttr.Length > 0)
    {
        foreach (MetadataTypeAttribute attr in metaAttr)
        {
            t = attr.MetadataClassType;
            pi = t.GetProperty(PropertyName);

            if (pi != null) isReadOnly = ReadOnlyAttribute.IsDefined(pi, typeof(ReadOnlyAttribute));

            if (isReadOnly) break;
        }
    }
}

Problem

I am trying to use reflection to check if properties on a given class have a ReadOnly attribute set. The classes I am using are MVC View Models (using a partial "buddy" class for the metadata. ``` public partial class AccountViewModel { public virtual Int32 ID { get; set; } public virtual decimal Balance { get; set; } } [MetadataType(typeof(AccountViewModelMetaData))] public partial class AccountViewModel { class AccountViewModelMetaData { [DisplayName("ID")] public virtual Int32 ID { get; set; } [DisplayName("Balance")] [DataType(DataType.Currency)] [ReadOnly(true)] public virtual decimal Balance { get; set; } } } ``` I want to check if "Balance" has the ReadOnly property. If i set the ReadOnly attribute on the Balance property of AccountViewModel, i can retrieve it this way: ``` Type t = typeof(AccountViewModel); PropertyInfo pi = t.GetProperty("Balance"); bool isReadOnly = ReadOnlyAttribute.IsDefined(pi,typeof( ReadOnlyAttribute); ``` I can't retrieve the attribute info if it is on the meta data class. How can i check if the attribute exists? I have meta data classes defined for all my view models, and need a generic way to check for attributes on meta data classes. Any suggestions?

Original source