Hello, I would like to get your suggestion about how to validate a user name input by checking if the name has already been taken (exists in the back-end database); and how to show feedback messages right next to the input field if it has.
Typically, when a user registers to a website, he needs to choose a user name, a password, etc. To make sure that the chosen name is unique, one needs to access the back-end database to check if it already exists. My solution right now is to extend "AbstractValidator<String>", and override "onValidate(IValidatable<String> validatable)" to put the database-checking logic in it. But the more I think about it, the more I felt it might be a wrong solution. The problem (I think, not 100% sure) is that "onValidate(IValidatable<String> validatable)" will be called during the form validation process, even if this process goes through, I may still find out later that the user chosen name has been taken when trying to save all the user inputs (name, password, etc) to the database. This happens when another user registers with the same name between the time the validation process finished and the time I start persisting all inputs from the first user to the database, So now I am trying to figure out another solution. Here is the idea: Instead of putting the database-checking logic into the validation process, I simply try to save all the user inputs into the database after receiving them. If an unique key exception happens, I know that the user chosen name has been taken. Now my questions are: 1. where should I put this save-catch-exception logic? Is "Form.onSubmit()" the right place to put it? 2. After I catch an unique key exception. How can I show a feedback message like "This name has already been taken" RIGHT NEXT to the user name input field? (Just like what a typical Wicket Validator does though "FeedbackPanel"). I am new to Wicket and your inputs and suggestions are greatly appreciated. Cheers Paul
