DataModel must implement org.primefaces.model.SelectableDataModel when selection is enabled. - jsf

Question

I'm trying to create a DataTable with Multiple Row Selection but i'm getting an error here's the link of the tutorial http://www.primefaces.org/showcase/ui/datatableRowSelectionMultiple.jsf :
Here's my xhtml:
<p:dataTable border="1" value="#{projectAdminisrationMB.projectNoUsersList}"
var="userObj"
selection="#
{projectAdminisrationMB.selectedUsers}"
selectionMode="multiple" rowIndexVar="rowIndex"binding="#{table2}">
<p:column id="column3">
<f:facet name="header">
<h:outputText value=" user "></h:outputText>
</f:facet>
<h:outputText value="#{userObj.name}"/>
/
<h:outputText value="#{userObj.lastName}"></h:outputText>
<h:outputText value="#{userObj.firstName}"></h:outputText>
</p:column>
<f:facet name="footer">
<p:commandButton id="addProjectUser" value=" Add " onclick="dlg1.show()" />
<p:commandButton id="deleteProjectUser" value=" Delete " />
</f:facet>
</p:dataTable>
Managed Bean :
#ManagedBean
#SessionScoped
public class ProjectAdminisrationMB implements Serializable {
private static final long serialVersionUID = 1L;
private String projectName;
private List <User> projectUsersList;
private List<User> projectNoUsersList;
private List<User> selectedUsers;
private String projectAdmin;
public ProjectAdminisrationMB() {
super();
AdministrationProjectFinal administrationProjectFinal =new
AdministrationProjectFinal();
this.projectUsersList=administrationProjectFinal.getUserList();
this.projectNoUsersList=administrationProjectFinal.getNotUserList();
}
public String getProjectName() {
return projectName;
}
public void setProjectName(String projectName) {
this.projectName = projectName;
}
public List<User> getProjectUsersList() {
return projectUsersList;
}
public void setProjectUsersList(List<User> projectUsersList) {
this.projectUsersList = projectUsersList;
}
public String getProjectAdmin() {
return projectAdmin;
}
public void setProjectAdmin(String projectAdmin) {
this.projectAdmin = projectAdmin;
}
public List<User> getProjectNoUsersList() {
return projectNoUsersList;
}
public void setProjectNoUsersList(List<User> projectNoUsersList) {
this.projectNoUsersList = projectNoUsersList;
}
public List<User> getSelectedUsers() {
return selectedUsers;
}
public void setSelectedUsers(List<User> selectedUsers) {
this.selectedUsers = selectedUsers;
}
}
i'm getting this error:
javax.faces.FacesException: DataModel must implement
org.primefaces.model.SelectableDataModel when selection is enabled.....

Answer 1

just add this attribute rowKey to the datatable tag :
<p:dataTable border="1" value="#{projectAdminisrationMB.projectNoUsersList}"
var="userObj"
rowKey="#{userObj.name}"selection="#{projectAdminisrationMB.selectedUsers}"
selectionMode="multiple" rowIndexVar="rowIndex"
binding="#{table2}">

Answer 2

You can get this error if you try to add a new item to the underlying list and forget to assign a value to that new item's rowKey.

Answer 3

Alternatively to rowKey you can wrap your data in a custom model which really implements org.primefaces.model.SelectableDataModel. This is helpful if
all of your your classes have the same kind of #Id (e.g. a long) and can implement the same interface (e.g. EjbWithId)
you want to add additional functionalities to your data which are not domain specific and don't belong e.g. User.
The interface may be something like this:
public interface EjbWithId
{
public long getId();
public void setId(long id);
}
Then a generic implementation of SelectableDataModel for all your classes can be used:
public class PrimefacesEjbIdDataModel <T extends EjbWithId>
extends ListDataModel<T> implements SelectableDataModel<T>
{
public PrimefacesEjbIdDataModel(List<T> data)
{
super(data);
}
#Override public T getRowData(String rowKey)
{
List<T> list = (List<T>) getWrappedData();
for(T ejb : list)
{
if(ejb.getId()==(new Integer(rowKey))){return ejb;}
}
return null;
}
#Override public Object getRowKey(T item) {return item.getId();}
}
In your #ManagedBean:
private PrimefacesEjbIdDataModel<User> dmUser; //+getter
dmUser = new PrimefacesEjbIdDataModel<User>(administrationProjectFinal.getUserList());

Answer 4

first check whether you've added
rowKey="#{userObj.id}"
then you need to have the data table List set in filteredValue attribute of your data table in xhtml, instead of value.