How to change css class for the inputfield and label when validation fails?

Question

Suppose I have a username to validate, in this case I need to show username outputText and username inputText field in red color when validation fails along with error messa

Answer 1

Bind the input component to the view via binding attribute. It'll become available as an UIInput component reference in EL, so that you can use UIInput#isValid() in styleClass attribute.

(note that I fixed your label to be a real label; also note that you don't need to create some bean property at all as suggested by the answer of cubbuk)

Yes, this may produce quite some non-DRY boilerplate code in the view. You can abstract this away with a phase listener or a system event listener. You can also use OmniFaces component which does all the job transparently. See also the live demo.