p:rowExpansion gets rendered even though it's not toggled - jsf

Question

I have a problem with data in a <p:rowExpansion> being loaded before the row is expanded (which leads to loads of web service requests).
I am using PrimeFaces 5.2. I have a dataTable with lazy loading and pagination. Inside of the table, I have <p:rowToggler> with a <p:rowExpansion>:
<p:dataTable var="order"
widgetVar="orderTable"
lazy="true"
value="#{ordersBean.orders}"
paginator="true"
rows="20"
rowsPerPageTemplate="20,50,100"
filterDelay="300"
styleClass="filtered">
<p:column width="4%">
<p:rowToggler />
</p:column>
<p:column headerText="Order number" width="96%">
<h:outputText value="#{order.number}" />
</p:column>
<p:rowExpansion>
<h:panelGrid columns="1">
<h:outputText value="#{order.number}" />
<h:outputText value="#{order.info}" />
<h:dataTable var="item" value="#{ordersBean.getItemsInOrder(order.number)}">
<h:column>
<h:outputText value=" #{item.title}" />
</h:column>
</h:dataTable>
</h:panelGrid>
</p:rowExpansion>
</p:dataTable>
When I first load the page, the getItemsInOrder() method is not called, except for when I expand a row. But if I navigate to page 2 (or if I navigate back to page 1 later) using the paginator, then getItemsInOrder() is called for every row in the outer table. Since I have 20 rows showing, navigating between the pages leads to 20 web service requests (in getItemsInOrder()).
How do I prevent it from calling the getItemsInOrder() method until the row is expanded?

Answer 1

I have the same problem. Until I find a better solution, this is the workaround I am using:
register a (DataTable event-) listener on event rowToggle.
In the listener, store an identifier of the toggled row. Hint: you can get the row object with event.getData()
Instead of directly accessing the data requesting component, write a proxy method in front of it which checks if the requested object belongs to the identifier stored in the listener.