JSF 2 : dynamic required validation for different buttons ?

Question

Hello,
I'm currently learning about jsf 2.0 from core jsf 2.0 book + glassfish + cdi.
I have a question about the validation feature of JSF.
Let's say i have a very simple login application, which has a very simple layout like :
userid : (input field for userid - using required="true")
password : (input secret for password - using required="true")
loginButton + registerButton(using immediate="true") + checkUserIdAvailabilityButton
Now, let's say the loginButton is pressed, and the userid and password are left empty, validation error would occur on both of the fields, and that's working as what i intended.
And when the registerButton is pressed, it doesnt care whether the userid or password is filled by the user, since it's using immediate="true", thus bypassing validation and the command gets executed at the apply request value phase, and that's still working as what i intended.
And here comes my problem .. When the checkUserIdAvailabilityButton is pressed, i only expect the userid to be filled, and i dont need to care about whether the password field is filled or not, but the password field will throw error saying that it's a required field.
Is there anyway to resolve this kind of problem ? I know this could be a very simple application, but in my working place, i think they design lots of screens like this, like the save button along with refresh button with different required fields but the buttons are in the same page.
Thank you !

Answer 1

Hello there !
Thank you for the response.
I agree with the server side approach. I also find it not easy to maintain lots of uncentralized validations on many jsf pages.
For example, validation on the my CustomerName's length could get replicated on hundreds of pages, and when the requirement changes, i have to update many pages.
But doing this on the serverside is not easy either, i suppose, got to have a custom framework to fill the needs. Im thinking of a general validator that could validate when supplied the variable's name, and the validator will know whether the field needs validating on the correctness of the date value, or the length of the fieldname, etc, based on some external configuration that says this variable is a type of date, with max length of this, min value of that, etc.
If i dont have this kind of tools, i'll also replicate all the validations like the CustomerName's case on many bean methods, which i think is not maintainable too.
Do you happen to know whether this kind of validation tools exist somewhere ? I dont think that bean validation framework from jsr 303 would fill my need, am i correct ?
Regards,
Albert Kam