Custom Model Binder inheriting from DefaultModelBinder

Question

I\'m attempting to build a custom model binder for MVC 4 that will inherit from DefaultModelBinder. I\'d like it to intercept any interfaces at any bin

Answer 1

With MVC 4 it is easy to override the messages, if that is all you might need in a custom model binder:

    protected void Application_Start(object sender, EventArgs e)
    {
        //set mvc default messages, or language specifc
        ClientDataTypeModelValidatorProvider.ResourceClassKey = "ValidationMessages";
        DefaultModelBinder.ResourceClassKey = "ValidationMessages";
    }

Then create resource file named ValidationMessages with entries like this:

NAME: FieldMustBeDate 
VALUE: The field {0} must be a date. 
NAME: FieldMustBeNumeric 
VALUE: The field {0} must be a number

.

We did this for a compliance failure. Our security scan did not like that a javascript injection would come back and appear in the Validation Messages and execute. By using this implementation we are overriding the default messages which return the user provided value.

Answer 2

This article showed me that I was over-complicating the model binder. The following code works:

public class InterfaceModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelType.IsInterface)
        {
            Type desiredType = Type.GetType(
                EncryptionService.Decrypt(
                    (string)bindingContext.ValueProvider.GetValue("AssemblyQualifiedName").ConvertTo(typeof(string))));
            bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(null, desiredType);
        }

        return base.BindModel(controllerContext, bindingContext);
    }
}