Mutually exclusive input fields with JSF and PrimeFaces - validation

Question

I have a PrimeFaces application where I would like to make two input text fields mutually exclusive: the user should fill either field, but not both.
In the following example, the user could search contacts either by phone number or by email.
<h:form>
<h:outputLabel>Phone Number:
<h:inputText id="phoneInput" value="#{contactSearch.phone}"
disabled="#{not empty contactSearch.email}">
<p:ajax event="keyup" update="emailInput"/>
</h:inputText>
</h:outputLabel>
<h:outputLabel>Email Address:
<h:inputText id="emailInput" value="#{contactSearch.email}"
disabled="#{not empty contactSearch.phone}">
<p:ajax event="keyup" update="phoneInput"/>
</h:inputText>
</h:outputLabel>
<!-- Possibly other fields... -->
<h:commandButton value="Search" action="#{contactSearch.search}"/>
</h:form>
Is this the proper way to do it? I am concerned about:
Possible "deadlock" issues, where both fields end up being disabled
The whole form being submitted and/or valdiated in the Ajax request, when I just would like to update the disabled state of the input field
Missing some predefined PrimeFaces control which does all the work :)

Answer 1

This is not trivial in standard JSF. JSF utility library OmniFaces has a validator for exactly this purpose, the <o:validateOne>.
<h:inputText id="email" ... />
<h:inputText id="phone" ... />
<o:validateOne components="email phone" />
However, in UX perspective, you'd better redesign your form to provide a single UISelectOne component to select the type and a single UIInput field to enter the value. E.g.
<h:selectOneRadio ... value="#{bean.type}">
<f:selectItem itemValue="email" />
<f:selectItem itemValue="phone" />
</h:selectOneRadio>
<h:inputText ... value="#{bean.value}" />
Update: as server side validation is not affordable and you'd really like to disable the the other without making much ajax traffic, your only bet is using pure JavaScript/jQuery for the job (if necessary in combination with server side validation as fallback).
Here's a generic jQuery based approach:
<h:inputText styleClass="onlyone" a:data-onlyone="groupName" />
<h:inputText styleClass="onlyone" a:data-onlyone="groupName" />
...
$(document).on("input", ":input.onlyone", function() {
var $this = $(this);
var $others = $("[data-onlyone='" + $this.data("onlyone") + "']").not($this);
$others.val(null).attr("disabled", !!$this.val());
});
The data-onlyone value should represent the group name, so you can have multiple of "only one" inputs throughout the document.