Question

I am working with MyFaces/Primefaces and I have a problem to get information using ajax.
My page contains a list of panel, inside each panel, the user can select value in a dropdown list, and click on a checkbox which will update its panel (Ajax), I hope I am clear.
This is my code:

<p:panel>
...
<h:selectOneMenu id="beanSet" value="#{myBean.selectedSet}">
    <f:selectItem itemLabel=" " noSelectionOption="true" />
    <f:selectItems value="#{langSet}" />
</h:selectOneMenu>


<h:selectBooleanCheckbox 
id="chkbxBeanSet"
value="#{myBean.selectedSetChkbx}" >
    <p:ajax 
    event="click" render="@parent"
    listener="#{action.updateSet}"
    execute="@form"
    immediate="true"
    />
</h:selectBooleanCheckbox>
...
<p:panel>

And here my java code:

public void updateSet(AjaxBehaviorEvent e) {
    UIComponent source = (UIComponent)e.getSource();
    System.out.println("Value:"+((HtmlSelectBooleanCheckbox)source).getValue());
    UIComponent parent = source.getParent();
    List<UIComponent> children = parent.getChildren();


    HtmlSelectOneMenu lvSet = (HtmlSelectOneMenu)parent.findComponent("beanSet");
    Object value = lvSet.getValue();
    System.out.println("value: " + value);

I get the beanSet component, but I can’t get its value. As I understand, the getValue calls the getSelectedSet from myBean which is not set (it is in request scope).
I don’t understant how I can get the selected value in the dropdown list using ajax.
Another way is to post all the form, but in that case, I have to determine which checkbox was clicked by the user…
If someone can explain me where I am wrong?

Answer 1

The culprit is immediate="true" on the ajax action. This will skip all input components which do not have this attribute set during the processing. You should finetune the to-be-processed components in the process attribute of <p:ajax>. Yes, another culprit is that you used execute instead of process. The <p:ajax> uses process where <f:ajax> uses execute. Also, the way how you accessed the dropdown value is unnecessarily overcomplicated. Just access the selectedSet property directly. JSF will set it in the same bean anyway.

So, this should do

<h:selectOneMenu id="beanSet" value="#{myBean.selectedSet}">
    <f:selectItem itemLabel=" " noSelectionOption="true" />
    <f:selectItems value="#{langSet}" />
</h:selectOneMenu>
<h:selectBooleanCheckbox id="chkbxBeanSet" value="#{myBean.selectedSetChkbx}">
    <p:ajax process="@this beanSet" listener="#{action.updateSet}" update="@parent" />
</h:selectBooleanCheckbox>

with

public void updateSet() {
    System.out.println(selectedSet);
}

Note that I omitted event="click" from <p:ajax>. It’s already the default for checkboxes.