Primefaces SelectCheckboxMenu null value

Question

I'm trying to get selected values from a selectCheckboxMenu, but all I'm getting is null in the console. It doesn't work with selectOneMenu too. Here's my jsf form:

<h:form id="mmaster">
        <p:dataTable
        value="#{devicesBean.devices}" 
        var="dev"
        widgetVar="dt"
        border="1" 
        paginator="true"
        paginatorPosition="top"
        rows="10"
        >
            <f:facet name="header">Devices</f:facet>
                        <p:column headerText="UDN" sortBy="#{dev.deviceUDN}" filterBy="#{dev.deviceUDN}" filterMatchMode="contains" emptyMessage="No Devices Found">
                <h:outputText value="#{dev.deviceUDN}" />
            </p:column>
            <p:column headerText="FriendlyName" sortBy="#{dev.deviceFriendlyName}" filterBy="#{dev.deviceFriendlyName}" filterMatchMode="contains">
                <h:outputText value="#{dev.deviceFriendlyName}" />
            </p:column>
            <p:column headerText="Model" sortBy="#{dev.deviceModel}" filterBy="#{dev.deviceModel}" filterMatchMode="contains">
                <h:outputText value="#{dev.deviceModel}" />
            </p:column>
            <p:column headerText="Manufacturer" sortBy="#{dev.deviceManufacturer}" filterBy="#{dev.deviceManufacturer}" filterMatchMode="contains">
                <h:outputText value="#{dev.deviceManufacturer}" />
            </p:column>
            <p:column headerText="Type" sortBy="#{dev.deviceType}" filterBy="#{dev.deviceType}" filterMatchMode="contains">
                <h:outputText value="#{dev.deviceType}" />
            </p:column>
        <p:column headerText="Actions">
        <p:selectCheckboxMenu value="#{devicesBean.selectAnnotations}">
        <f:selectItems value="#{devicesBean.annotations}" />
        </p:selectCheckboxMenu>           
        </p:column>
        <p:column>
        <p:commandButton value="Annotate" action="#{devicesBean.doSave}" process="@this">
        <f:setPropertyActionListener value="#{dev}" target="#{devicesBean.device}" />
        </p:commandButton> 
        </p:column>
    </p:dataTable>
</h:form>

I wonder if there is a problem in the bean's scope, And this is my managed bean:

@ManagedBean
public class DevicesBean implements Serializable {

    private static final long serialVersionUID = 1L;
    private List<Device> devices;
    private List<String> annotations;
    private List<String> selectAnnotations = new ArrayList<String>();
    private Device device;

    @EJB
    IOntoProcessor iop;
    @EJB
    IDevicesDao idd;

    public DevicesBean() {
    }

    @PostConstruct
    public void init() {
        setDevices(idd.getAllDevices());
        setAnnotations(iop.getAllAnnotations());
    }

    public List<Device> getDevices() {
        return devices;
    }

    public void setDevices(List<Device> devices) {
        this.devices = devices;
    }

    public List<String> getAnnotations() {
        return annotations;
    }

    public void setAnnotations(List<String> annotations) {
        this.annotations = annotations;
    }

    public Device getDevice() {
        return device;
    }

    public void setDevice(Device device) {
        this.device = device;
    }

    public List<String> getSelectAnnotations() {
        return selectAnnotations;
    }

    public void setSelectAnnotations(List<String> selectAnnotations) {
        this.selectAnnotations = selectAnnotations;
    }

    public void doSave() {
        System.out.println(selectAnnotations);
        System.out.println(device);
        selectAnnotations = new ArrayList<String>();
    }

}

Answer 1

You are trying to submit the form through the Button with value Annotate, which has been specified to process itself only:

This will only process the button and its associated form parameters, and no other element within the form.

<p:commandButton value="Annotate" action="#{devicesBean.doSave}" process="@this">
    <f:setPropertyActionListener value="#{dev}" target="#{devicesBean.device}" />
</p:commandButton> 

Either remove the process="@this", or replace it with process="@form"

<p:commandButton value="Annotate" action="#{devicesBean.doSave}" process="@form">
    <f:setPropertyActionListener value="#{dev}" target="#{devicesBean.device}" />
</p:commandButton> 

Two, declare your managed bean scope: Either @RequestScope or @SessionScoped will work fine.