Make components required depending on selectOneRadio value - ajax

Question

JSF2, PrimeFaces 4.0
There is a form with multiple inputFields and a selectOneRadio (and some action button at the end):
<p:outputLabel for="R1" value="R1" />
<p:selectOneRadio id="R1" value="#{bean.r1Value}" required="#{bean.r1Condition}" converter="SomeConverter" >
<f:selectItems value="#{bean.r1PossibleValues}" var="r1Var" itemValue="#{r1Var}" itemLabel="#{r1Var}" />
<p:ajax process="#form" update="#form" />
</p:selectOneRadio>
<p:outputLabel for="F1" value="F1" />
<p:inputText id="F1" value="#{bean.value1}" required="#{bean.condition1}" />
<p:outputLabel for="F2" value="F2" />
<p:inputText id="F2" value="#{bean.value2}" required="#{bean.condition2}" />
If user selects first value of selectOneRadio - field F1 should be required, if second - field F2.
Methods bean.conditionX check the value of radio (and one more condition) and return true/false.
If I select first radio value, field F1 changes to required. Then, if I change my mind select second radio value - I get validation error (that field F1 is required).
If I change:
<p:ajax process="#form" update="#form" />
to:
<p:ajax update="#form" />
and then:
- enter some values into F1 and F2,
- select a value in radio
-> the values entered into fields F1, F2 disappear.
How can I change set of required fields on selectOneRadio change without losing data and without premature validation errors?

Answer 1

Remove the process attribute to <p:ajax> in order to make selectOneRadio trigger a partial Ajax request, that only submits the selectOneRadio itself. Fill the update attribute with a space-separated list of the components you need to update, excluding the inputText components, because you want to preserve their values, and their required status will be evaluated only when submitting the entire form. Finally, use the listener property of <p:ajax> for invoking a server method that updates the conditions that make the inputText components required:
<p:selectOneRadio id="R1" value="#{bean.r1Value}" required="#{bean.r1Condition}" converter="SomeConverter" >
<f:selectItems value="#{bean.r1PossibleValues}" var="r1Var" itemValue="#{r1Var}" itemLabel="#{r1Var}" />
<p:ajax listener="#{bean.myListener()}" update="label1 label2" />
</p:selectOneRadio>
<p:outputLabel id="label1" for="F1" value="#{myBean.condition1 ? '*' : ''}" />
<p:inputText id="F1" value="#{bean.value1}" required="#{bean.condition1}" />
<p:outputLabel id="label2" for="F2" value="#{myBean.condition2 ? '*' : ''}" />
Where
public void myListener() {
// changes the values of the required conditions based on selected value
condition1 = true;
condition2 = false;
}