Primefaces slected row id == null - jsf

Question

I have a working datatable that can list out restaurant objects.
I want to delete/edite the selected ones but when I select one the following exception shows up:
org.springframework.dao.InvalidDataAccessApiUsageException: The given id must not be null!
Here is the table:
<h:form id="restaurantForm">
<p:dataTable var="restaurant"
value="#{restaurantLazyBean.lazyDataModel}" paginator="true"
rows="10" rowsPerPageTemplate="5,10,50" id="carTable" lazy="true"
selectionMode="single" selection="#{RestaurantEditBean.selected}"
rowKey="#{restaurant.id}"
paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}">
<p:ajax event="rowSelect"
listener="#{RestaurantEditBean.onRowSelect()}"/>
<p:column headerText="ID">
<h:outputText value="#{restaurant.id}" />
</p:column>
</p:dataTable>
</h:form>
Now all ids appear in the table but on selection the exception shows up.
I tried to do everything according to the primefaces example. But they didn't even have the rowKey attribute.
Heres the bean if thats relevant.
#Named("RestaurantEditBean")
#ViewScoped
#EJB(name = "ejb.RestaurantService", beanInterface = RestaurantService.class)
public class RestaurantEditBean {
#EJB
private RestaurantService restaurantService;
private RestaurantDTO selected;
public void onRowSelect(SelectEvent event) {
selected = ((RestaurantDTO) event.getObject());
}
public RestaurantService getRestaurantService() {
return restaurantService;
}
public void setRestaurantService(RestaurantService restaurantService) {
this.restaurantService = restaurantService;
}
public RestaurantDTO getSelected() {
return selected;
}
public void setSelected(RestaurantDTO selected) {
this.selected = selected;
}
}
Primefaces: 5.3
JSF: 2.2

Answer 1

I found out that I did a terrible mistake.
In my LazyDataModel I had to override a function.
#Override
public RestaurantDTO getRowData(String rowKey) {
Long id = Long.parseLong(rowKey);
return restaurantService.findById(id);
}
The issue was cause by the previous Long.getLong(rowKey) and that one returned null.