How to hide validatorMessage when field is empty - jsf

Question

Please help how to hide validatorMessage when user clearing the field:
<div class="item">
<p:outputLabel for="firstName" value="#{msgs['customerForm.firstName']}"/>
<p:inputText id="firstName" value="#{customerBean.customer.firstName}"
requiredMessage="#{msgs['Error.firstName.mandatory']}"
validatorMessage="#{msgs['Error.firstName.wrongFormat']}"required="true">
<f:validateRegex pattern="^([a-zA-Z]+[a-zA-Z\s\-]*){1,255}$" />
</p:inputText>
<p:message id="m_firstName" for="firstName" display="text"/>
</div>

Answer 1

You defined your field having two validations:
* required value validator
* regular expression validator
Both validators have equivalent priority, and both are run against your field value. And both of these validators see empty value as a problem, and your framework, unable to determine which of these two equivalent-looking failures is the "actual" failure, displays both.
To "fix" it, you should allow empty values to pass your regex, like this:
<f:validateRegex pattern="^([a-zA-Z]+[a-zA-Z\s\-]*){0,255}$" />
Notice that I changed number qualifier to allow 0-255 characters instead of 1-255 characters like before.
That should allow two of your validators cover different cases of invalid values, like you intended.

Answer 2

You can update the error messages if you put this in the input element. It will validate the input on every keyup event though.
<f:ajax execute="#this" event="keyup" render="m_firstName" />