How can I update twice during JSF Ajax event - ajax

Question

Given the following code:
<p:column headerText="#{text.article}">
<h:panelGroup>
<p:autoComplete id="relationArticle"
value="#{relation.article}"
completeMethod="#{articleRelationsModel.findArticles}"
queryDelay="#{text.query_delay}"
minQueryLength="#{text.artikkel_min_query_length}"
var="article"
itemLabel="#{article.articleNo} #{article.text1}"
itemValue="#{article}"
converter="#{articleConverter}"
scrollHeight="150"
forceSelection="true"
styleClass="ui-autocomplete-big">
<p:ajax event="itemSelect" update="relationUnit" process="#this"/>
</p:autoComplete>
<p:message for="relationArticle"/>
</h:panelGroup>
</p:column>
<p:column headerText="#{text.unit}" style="width: 80px;">
<h:selectOneMenu id="relationUnit" value="#{relation.unit}" converter="#{articleUnitConverter}">
<f:selectItem itemLabel="<< #{text.search}" noSelectionOption="true" itemDisabled="#{relation.article != null}"/>
<f:selectItems value="#{articleRelationsModel.getUnits(relation)}" var="unit" itemLabel="#{unit.code}" itemValue="#{unit}"/>
<p:ajax event="change" process="#this" update="#this"/>
</h:selectOneMenu>
<p:message for="relationUnit"/>
</p:column>
How can I refresh the "relationUnit" component after the user has selected a value in the "relationArticle" component?
What happens now, is that after the autcompete itemSelect event has fired, the "relationUnit" component gets updated with new content using #{articleRelationsModel.getUnits(relation)}. During this update, the relation object is updated with one of the options from the resulting list. This, however, is not reflected in the "relationUnit" component after the update. But if I manually do another update after this, it gets selected.
How can I achieve the wanted result here?

Answer 1

You can use p:remoteCommand, which is usually used to call the ManagedBean Methods from Javascript.
While it serves the above purpose you can use it to update other components also.
You can call the p:remoteCommand from p:ajax's oncomplete attribute.
<p:autoComplete id="relationArticle" ...>
<p:ajax event="itemSelect" update="relationUnit" onComplete="updateRelationUnit()" process="#this"/>
</p:autoComplete>
<p:remoteCommand name="updateRelationUnit" update="relationUnit" process="#this" />
Now p:ajax will update relationUnit once and then calls the p:remoteCommand which in-turn relationUnit again.
I don't know why you want this strange behavior, but the above strategy and code servers your purpose just fine.