Hey,

I am trying to build some custom validation for products. I need to validate fields on an Extended Content Type.

As a test I wanted to see if I can cancel the Saving event. I tried the following:

    public class ProductValidationEventHandler : ApplicationEventHandler
{
    protected override void ApplicationStarted(UmbracoApplicationBase umbracoApplication,
        ApplicationContext applicationContext)
    {
        ProductService.Saving += ValidateProduct; // rasied before the content has been saved.
        base.ApplicationStarted(umbracoApplication, applicationContext);
    }

    private void ValidateProduct(IProductService sender, SaveEventArgs<IProduct> e)
    {
        e.CancelOperation(new EventMessage("Validation", "TEST - THIS SHOULD NOT SAVE", EventMessageType.Error));
    }
}

While the code is called, and the save appears to be cancelled, the message is not being displayed.

Am I using the right event? Is there another approach to custom validation in Merchello?