Primefaces Datatable dynamic calculation - primefaces

Question

In my view layer, I use a Primefaces Datatable with 9 columns, which the last one has float values (column name= 'Valor').
There is an integer column named 'prefDep' which has a filter for its values (foreignKey values, by the way):
<!-- column name omitted -->
<p:column sortBy="#{item.prefDep}" filterBy="#{item.prefDep}">
<h:outputText value="#{item.prefDep}"/>
</p:column>
The last row of the Datatable has a fixed GrandTotal, which is the overall sum of the mentioned 'Valor' column:
<p:columnGroup type="footer">
<p:row>
<p:column colspan="8" footerText="Grand Total:" />
<p:column footerText="#{upbController.totalLosses}" />
</p:row>
</p:columnGroup>
Method in the controller class to get the overall sum:
public int getTotalLosses() {
int total = 0;
for(Upb id : getItems()) {
total += id.getValor();
}
return total;
}
What I want: as I filter the Datatable, I want to show the corresponding GrandTotal for that filtered portion of values only, and not the 'fixed' overall sum.
How can I do it?
Thanks in advance.
--
After section:
In my AbstractController I have:
private List<T> filteredUpb;
//...
public List<T> getFilteredUpb() {
if (filteredUpb == null) {
filteredUpb = this.ejbFacade.findAll();
}
return filteredUpb;
}
In my UpbController (managedBean):
private List<Upb> filteredUpb = null;
//...
public int getPerdasTotal() {
int total = 0;
for (Upb id : getFilteredUpb()) {
total += id.getVlOco();
}
return total;
}
In jsf:
<p:column>
<f:facet name="footer">
<h:outputText value="#{upbController.perdasTotal}" />
</f:facet>
</p:column>

Answer 1

Just to not let this question unanswered, the solution (see below) for this question can be found in this other post of mine: Dynamic Calculation Using Filter in Datatable
I think that you can define AJAX calls on PF datatable filtering and/or paging.
<p:dataTable value="#{myBackingBean.values}" var="row" filteredValue="#{myBackingBean.filteredValues}" >
<p:ajax event="filter" listener="#{myBackingBean.updateSum}" update="componentToUpdate" />
//...
</p:dataTable>
In your updateSum() method, you can walk through the filteredValues collection to do your business.
You may have some difficulties to target the update component enclosed in the datatable but this can be resolved by adding something like styleClass="footerToUpdate" to your code and using it in the update with update="#(.footerToUpdate)"