FacesException: DataModel must implement org.primefaces.model.SelectableDataModel when selection is enabled

Asked 10/5, 2012 at 2:41 Answered 22/11, 2016 at 12:56

I am trying to learn PF so I started with displaying datatable first and navigating to next page on rowClick passing parameters, but got stuck with the following error. I found similar problem for that question but no luck yet. I hope somebody will help me out.

I am getting following error:

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

Caused by:
javax.faces.FacesException - DataModel must implement org.primefaces.model.SelectableDataModel when selection is enabled.

my Page:

 <?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:p="http://primefaces.org/ui">

<h:head>
<title>Primefaces 3.1</title>

</h:head>
<h:body>
    <h:form id="form">          
            <p:dataTable value="#{tableBean.cars}" var="var" rowkey="#{var.model}" 
            selection="#{tableBean.car}" selectionMode="single">
            <p:column>  <f:facet name="header">
                                <h:outputText styleClass="outputText" value="Model"></h:outputText>
                            </f:facet>
                            <h:outputText styleClass="outputText"
                                value="#{var.model}"></h:outputText>
                        </p:column>
                        <p:column>
                            <f:facet name="header">
                                <h:outputText styleClass="outputText" value="Color"></h:outputText>
                            </f:facet>
                            <h:outputText styleClass="outputText"
                                value="#{var.randomColor}"></h:outputText>
                        </p:column></p:dataTable>                               
        </h:form>
</h:body>
</html>

my bean Classes:

@ManagedBean
@ViewScoped
public class TableBean extends ListDataModel<Car> implements SelectableDataModel<Car>{

    private List<Car> cars;
    private Car car;

    public List<Car> getCars() {

        cars = new ArrayList<Car>();
        Car car1 = new Car();
        car1.setModel("BMW");
        car1.setRandomColor("Black");
        cars.add(car1);
        Car car2 = new Car();       
        car2.setModel("Audi");
        car2.setRandomColor("White");
        cars.add(car2);

        return cars;
    }

    public String onRowSelect(){
        System.out.println("Row Click!!!");
        return "otherpage";//Does this nav works???if not how???
    }

    public Car getCar() {
        return car;
    }

    @Override
    public Car getRowData(String pArg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Object getRowKey(Car pArg0) {
        // TODO Auto-generated method stub
        return null;
    }   
    }

OtherBean:

public class Car{

    private String model;   
    private String randomColor; 

    public String getRandomColor() {
        return randomColor;
    }
    public void setRandomColor(String pRandomColor) {
        randomColor = pRandomColor;
    }

    public String getModel() {
        return model;
    }
    public void setModel(String pModel) {
        model = pModel;
    }

}

Ib answered 10/5, 2012 at 2:41 Comment(0)

The #{tableBean.cars} must implement SelectableDataModel if you don't specify the rowKey attribute on the <p:dataTable>.

You have however implemented it on the #{tableBean} instead. This is not right. You can find correct examples in the PrimeFaces showcase. Basically, your TableBean class must look like this according to the showcase code example:

@ManagedBean
@ViewScoped
public class TableBean implements Serializable {

    private List<Car> cars;
    private Car car;
    private CarDataModel carsModel;

    public TableBean() {
        cars = new ArrayList<Car>();
        // Populate cars here and thus NOT in the getter method!
        carsModel = new CarDataModel(cars);
    }

    // ...
}

Where the CarDataModel look like this (again, just copied from PrimeFaces showcase code example):

public class CarDataModel extends ListDataModel<Car> implements SelectableDataModel<Car> {  

    public CarDataModel() {
    }

    public CarDataModel(List<Car> data) {
        super(data);
    }

    @Override
    public Car getRowData(String rowKey) {
        List<Car> cars = (List<Car>) getWrappedData();

        for(Car car : cars) {
            if(car.getModel().equals(rowKey))
                return car;
        }

        return null;
    }

    @Override
    public Object getRowKey(Car car) {
        return car.getModel();
    }

}

Finally use #{tableBean.carsModel} instead of #{tableBean.cars} as value of <p:dataTable>. Exactly as in the showcase example.

<p:dataTable value="#{tableBean.carsModel}" var="car" ... />

Another, easier, way is to just specify the rowKey attribute on the <p:dataTable>.

<p:dataTable value="#{tableBean.cars}" var="car" rowKey="#{car.model}" ... />

This way you don't need the whole SelectableDataModel. You only need to ensure that it's never null and always unique across the rows. See also DataModel must implement org.primefaces.model.SelectableDataModel when selection is enabled, but I have already defined rowKey.

Verdie answered 10/5, 2012 at 3:6 Comment(8)

Thanks for the comment, BalusC, I have couple of questions, what is the use of rowKey? Is it for the unique value for the column of the table being displayed? What if I have lets say 2 primary key in the same table. Another question is, What do you mean by if I use rowKey I dont have to implement CarDataModel, can you explain little bit...and also can you put some light on what selection attribute does in <P:table>. – Ib 10/5, 2012 at 7:37

The rowKey basically tells PrimeFaces what the unique identifier is of the row. The selection basically tells PrimeFaces where it has to get/set the references of selected rows. The point of SelectableDataModel is to be able to identify unique rows based on other criteria than what is already available by the row object itself (for which you would need rowKey). – Verdie 10/5, 2012 at 16:56

What we do if there are 2 primary keys, what we do in such scenario? – Ib 10/5, 2012 at 17:16

Either use a composite key or create a SelectableDataModel. – Verdie 10/5, 2012 at 17:25

Note that you may still get the same error even though you may have defined a rowKey attribute if the said attribute returns null (e.g. it's not initialized). – Stoughton 30/10, 2012 at 7:26

For a unique object identity rowKey="#{car.hashCode()}" would be ok? Depends on your hashCode() and equals() implementation of course, but if not overwritten it is unique for each instance. – Arquit 7/10, 2015 at 8:44

@opfau: hashcode doesn't per definition represent identity of the class' instance (multiple different instances can have same hashcode, you see, int has a hard limit in available values), but equals does (and does not force a limit anywhere). – Verdie 7/10, 2015 at 8:49

Indeed that's not a good idea even the hashCode() implementation depends on the JVM. – Arquit 7/10, 2015 at 9:29

Ensure to set the rowKey parameter in the bean method that populates the "value=.." of the datatable. Mine returned this error because the rowKey was null.

Cenobite answered 22/11, 2016 at 12:56 Comment(0)

It worked for my project using a composite key for rowkey e.g.: rowKey="#{course.getCompositeKey()

Since I didn't have a compositeKey variable I simply created one in my Course Class (in your case the Car Class). The 2 primary keys are strings so I just said this.compositeKey=this.courseNumber+this.product--you just use whatever 2 primary keys are in your Car class instead of courseNumber and product.

Impignorate answered 26/4, 2013 at 18:12 Comment(0)

Youd on't have to implement the datamodal in your managedbean, just specify in the proprety of the datatable the "rowkey" like this: rowkey="{mbean.atribute1}"
-- atribute1 must be diplayed in the data table column.

Must

Nicknickel answered 26/1, 2014 at 14:18 Comment(1)

The rowkey param is not required to be displayed as a column in the data table. – Camphorate 8/7, 2015 at 4:16

Must

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