Passing value to the backing bean with PrimeFaces

I am trying to upload the file and pass one parameter from select box with PrimeFaces 3.5.

This is my form:

<h:form id="idAssessmentsUploadForm" enctype="multipart/form-data">

    <h:panelGrid cellspacing="10" styleClass="standard-panel" columns="2" id="idAssessmentsUploadPanelGrid">

        <h:outputText value="#{msg['application.assessmentsUploadRequest.loader']}"/>
        <p:selectOneMenu id="idLoader"
                         style="width: 230px;"
                         required="true"
                         value="#{configurationBean.loaderName}">

            <f:selectItems value="#{configurationBean.loaders}"/>

        </p:selectOneMenu>

    </h:panelGrid>

    <p:fileUpload fileUploadListener="#{configurationAction.processConfigurationUpload}"
                  allowTypes="/(\.|\/)(gif|jpe?g|png)$/"
                  update="messages"
                  mode="advanced"/>

</h:form>

ConfiguratioBean is just a JSF @ViewScoped bean which contains getter and setter for loaderName.

My ConfigurationAction bean:

@ManagedBean(name = Beans.CONFIGURATION_ACTION)
@ViewScoped
public class ConfigurationAction extends BaseAction {

    public void processConfigurationUpload(FileUploadEvent event) {

        ConfigurationBean configurationBean = getBean(Beans.CONFIGURATION_BEAN);

        UploadedFile file = event.getFile();

        addInfoMessage("Upload Successful");
    }

}

I am receiving the file when I click upload, but the parameter loaderName is always null from the configurationBean. If I try to switch file upload to simple mode, put the file as a value in configurationBean and have a command button to upload the single file, then it is working. But I need upload to be advanced. So the question is how to pass the parameter to the backing bean if PrimeFaces file upload form is in advanced mode?

Use remoteCommand for this. For e.g.:

<h:form id="idAssessmentsUploadForm" enctype="multipart/form-data">

    <h:panelGrid cellspacing="10" styleClass="standard-panel" columns="2" id="idAssessmentsUploadPanelGrid">

        <h:outputText value="#{msg['application.assessmentsUploadRequest.loader']}"/>
        <p:selectOneMenu id="idLoader"
                         style="width: 230px;"
                         value="#{configurationBean.loaderName}"
                         required="true">

            <f:selectItems value="#{configurationBean.loaders}"/>

        </p:selectOneMenu>

    </h:panelGrid>

    <p:fileUpload fileUploadListener="#{configurationAction.processConfigurationUpload}"
                  allowTypes="/(\.|\/)(gif|jpe?g|png)$/"
                  required="true"
                  onstart="loadProperty()"
                  update="messages"
                  mode="advanced"/>

    <p:remoteCommand name="loadProperty">
        <f:setPropertyActionListener for="idLoader"
                                     value="#{configurationBean.loaderName}"
                                     target="#{configurationBean.loaderName}"/>
    </p:remoteCommand>

</h:form>

Not tested but should work.