selectOneMenu ajax events - ajax

Question

I am using an editable primefaces selectOneMenu to display some values. If the user selects an item from the List a textarea should be updated. However, if the user types something in the selectOneMenu, the textarea should not be updated.
I thought I could work this with ajax event out. However, I don't know which event I can use here. I only know the valueChange event. Are there any other events, like onSelect or onKeyUp?
Here is my code:
<p:selectOneMenu id="betreff" style="width: 470px !important;"
editable="true" value="#{post.aktNachricht.subject}">
<p:ajax event="valueChange" update="msgtext"
listener="#{post.subjectSelectionChanged}" />
<f:selectItems value="#{post.subjectList}" />
</p:selectOneMenu>
<p:inputTextarea style="width:550px;" rows="15" id="msgtext"
value="#{post.aktNachricht.text}" />

Answer 1

The PrimeFaces ajax events sometimes are very poorly documented, so in most cases you must go to the source code and check yourself.
p:selectOneMenu supports change event:
<p:selectOneMenu ..>
<p:ajax event="change" update="msgtext"
listener="#{post.subjectSelectionChanged}" />
<!--...-->
</p:selectOneMenu>
which triggers listener with AjaxBehaviorEvent as argument in signature:
public void subjectSelectionChanged(final AjaxBehaviorEvent event) {...}

Answer 2

I'd rather use more convenient itemSelect event. With this event you can use org.primefaces.event.SelectEvent objects in your listener.
<p:selectOneMenu ...>
<p:ajax event="itemSelect"
update="messages"
listener="#{beanMB.onItemSelectedListener}"/>
</p:selectOneMenu>
With such listener:
public void onItemSelectedListener(SelectEvent event){
MyItem selectedItem = (MyItem) event.getObject();
//do something with selected value
}

Answer 3

Be carefull that the page does not contain any empty component which has "required" attribute as "true" before your selectOneMenu component running.
If you use a component such as
<p:inputText label="Nm:" id="id_name" value="#{ myHelper.name}" required="true"/>
then,
<p:selectOneMenu .....></p:selectOneMenu>
and forget to fill the required component, ajax listener of selectoneMenu cannot be executed.

Answer 4

You could check whether the value of your selectOneMenu component belongs to the list of subjects.
Namely:
public void subjectSelectionChanged() {
// Cancel if subject is manually written
if (!subjectList.contains(aktNachricht.subject)) { return; }
// Write your code here in case the user selected (or wrote) an item of the list
// ....
}
Supposedly subjectList is a collection type, like ArrayList. Of course here your code will run in case the user writes an item of your selectOneMenu list.