This customization displays a custom validation error message by setting the ErrorMessage and Text properties of a Validator control. The ErrorMessage property of a Validator control is displayed in a pop-up window while the Text property is displayed at the location of the validator on the web page. This property is set at design time, but can be changed via the tag's Properties dialog. To change it, you simply add or modify the pass-through attributes located in the Attributes tab of the FieldValue tag.

You can only set the RequiredFieldValidator for a FieldValue control. Additional validation can be implemented by overriding the Validate() method in the RecordControl class.

If you try to add a new record without a ProductName, you will see something like this:

Step 1:  Display the Properties dialog and select the FieldValue that you wish to modify in a page.

Step 2:  Go to the Attributes tab for the selected FieldValue and add the attributes.

Step 3:  Build and run the application.