ASP.NET MVC ModelMetaData: Is there a way to set IsRequired based on the RequiredAttribute?

Question

Brad Wilson posted a great blog series on ASP.NET MVC\'s new ModelMetaData: http://bradwilson.typepad.com/blog/2009/10/aspnet-mvc-2-templates-part-2-modelmetadata.html

Answer 1

You need to create your own ModelMetadataProvider. Here's an example using the DataAnnotationsModelBinder

public class MyMetadataProvider : DataAnnotationsModelMetadataProvider
{
        protected override ModelMetadata CreateMetadata(Collections.Generic.IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName)
        {
            var _default = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName);
            _default.IsRequired = attributes.Where(x => x is RequiredAttribute).Count() > 0;
            return _default;
        }
}

Then in your AppStartup in Global.asax, you will want to put the following in to hookup the MyMetadataProvider as the default metadata provider:

ModelMetadataProviders.Current = new MyMetadataProvider();