Following along with the book in chapter 6, I put the TemplatedCreditCardForm on a web page and in VisualStudio when trying to build the website errors would be displayed like the following:

Error 1 Cannot switch views: Content is not allowed between the opening and closing tags for element 'TemplatedCreditCardForm'.

The errors prevented the page from being displayed in design view. I figured out how to resolve the issue by adding the PersistenceMode attribute to the template properties like so:

        private ITemplate paymentMethodLabelTemplate;
        [PersistenceMode(PersistenceMode.InnerProperty)]
        public ITemplate PaymentMethodLabelTemplate
        {
            get { return paymentMethodLabelTemplate; }
            set { paymentMethodLabelTemplate = value; }
        }

        private ITemplate creditCardNoLabelTemplate;
        [PersistenceMode(PersistenceMode.InnerProperty)]
        public ITemplate CreditCardNoLabelTemplate
        {
            get { return creditCardNoLabelTemplate; }
            set { creditCardNoLabelTemplate = value; }
        }

        private ITemplate cardholderNameLabelTemplate;
        [PersistenceMode(PersistenceMode.InnerProperty)]
        public ITemplate CardholderNameLabelTemplate
        {
            get { return cardholderNameLabelTemplate; }
            set { cardholderNameLabelTemplate = value; }
        }

        private ITemplate expirationDateLabelTemplate;
        [PersistenceMode(PersistenceMode.InnerProperty)]
        public ITemplate ExpirationDateLabelTemplate
        {
            get { return expirationDateLabelTemplate; }
            set { expirationDateLabelTemplate = value; }
        }

Hopefully this will help out others that experience this same issue.

Hi, oldSkool,
The error you're seeing is a design time error not a compilation and runtime error. In other words, the application should compile and run without any problems.

As you rightly mentioned, the missing PersistenceMode attribute is the cause of this design time error. Thanks for catching this error.

Regards,
Shahram

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Shahram Khosravi, Ph.D.
Author of Professional ASP.NET 2.0 Server Control and Component Development