How to show messages in p:dialog? - jsf

Question

I need your help in showing an error message in the dialog. By clicking on the commandButton, no message is shown in the dialog.
Even though I tried to show the message in a dialog, but nothing is shown without any error.
So how can I produce messages in a dialog and not in the main form
Here is the JSF page code:
<h:form id="Requests">
<p:messages id="messages" showDetail="true" autoUpdate="true" closable="true"/>
<p:dialog id="c1" header="C1" widgetVar="c1">
<p:message id="messagePDFSTAR"
for=":Requests:DownloadPDFSTAR"
showDetail="true" />
<p:commandButton id="DownloadPDFSTAR"
value="Download"
ajax="false"
actionListener="#{hrd.PDFSTAR}"
update=":Requests:messagePDFSTAR" >
<p:fileDownload value="#{hrd.fileSTAR}" />
</p:commandButton>
</p:dialog>
</h:form>
Here is the java bean code:
public void PDFSTAR() {
try {
FacesMessage message = new FacesMessage(FacesMessage.SEVERITY_INFO, "Ref is Null", "Ref is Null");
RequestContext.getCurrentInstance().showMessageInDialog(message);
FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_FATAL, "Fatal!", "System Error"));
} catch (Exception e) {
e.printStackTrace();
}
}

Answer 1

It's because you have ajax=false at the commandButton, so, the attribute update::Requests:messagePDFSTAR isn't going to work.
You can't combine ajax=false and update="...", update attribute is only for ajax actions.
I understand you need the ajax=false because the p:fileDownload works with that, but maybe you can try another way to display the message you want.
I deal with that situation once and use a workaround, in p:dialog you can use a p:messages and autoUpdate=true.
<h:form id="Requests">
<p:messages id="messages" showDetail="true" autoUpdate="true" closable="true"/>
<p:dialog id="c1" header="C1" widgetVar="c1">
<p:messages id="messagesPDFSTAR"
autoUpdate="true"
showDetail="true" />
<p:commandButton id="DownloadPDFSTAR"
value="Download"
ajax="false"
actionListener="#{hrd.PDFSTAR}" >
<p:fileDownload value="#{hrd.fileSTAR}" />
</p:commandButton>
</p:dialog>
</h:form>
I hope that will help you.
Edit:
RequestContext.getCurrentInstance().showMessageInDialog(message);
It shows the message in a new dialog, but i think it's not what you want. You want to show the message in the same dialog of the commandButton and the fileDownLoad.
Ajax and update not working correctly

Answer 2

To update components as p:growl or p:messages after a download, or even at the start just use a p:remoteCommand and the PrimeFaces.monitorDownload(start, stop); as in the example provided here PrimeFaces File Download example
here is how I'd do it:
<script type="text/javascript">
function start() {
PF('statusDialog').show();
//maybe some other blah blah..
updateMyMessages();
}
function stop() {
PF('statusDialog').hide();
//maybe some other blah blah..
updateMyMessages();
}
</script>
<div class="card">
<p:dialog modal="true" widgetVar="statusDialog" header="Status" draggable="false" closable="false"
resizable="false">
<i class="pi pi-spinner pi-spin" style="font-size:3rem"></i>
</p:dialog>
<h:form>
<p:messages id="messagesPDFSTAR"/>
<p:remoteCommand name="updateMyMessages" update="messagesPDFSTAR" action="#{hrd.PDFSTAR}"/>
<p:commandButton value="Download" ajax="false" onclick="PrimeFaces.monitorDownload(start, stop);"
icon="pi pi-arrow-down" styleClass="p-mr-2">
<p:fileDownload value="#{fileDownloadView.file}"/>
</p:commandButton>
</div>
Please note that I called the remote command twice so you get two updates to your messages, also this will execute your action #{hrd.PDFSTAR} twice, once on download start and the other on download finish, so modify as you see fit.
You can always upgrade to PrimeFaces 10+ and use ajax="true" (the default) on the download command button.