Undo row selection of af:table in selection listener method conditionally

Recently I have seen a question on OTN Jdeveloper forum and It was about table selection listener
Requirement is like this suppose user has to check a condition after selecting a row and if that condition is true only then new row will be selected else selected row should be previous one

It means undo row selection on validation(condition) failure
So In this post I am implementing same scenario and here I am using Departments table of HR Schema to prepare model and condition is that user should be able to select new row only if ManagerId is not null

Custom selection listener for af:listView, Invoke selectionListener programmatically

In the last post (Better UI for data collection using af:listView, Enable selection in ADF Faces List component ) about af:listView, we saw that how can we present data collection in a better way using af:listView and enable selection using EL (same as used for af:table)

Now in this post i will describe about defining custom selection listener for af:listView
Suppose you have to do some task on selection of an item in list other than making it current row, for this you have to override default selection listener and define own custom selection listener in managed bean
So next step is to define a method in managed bean for handling selection event of af:list view

• Select af:listView, goto properties and click on edit menu of selectionListener property and create a method in managed bean








• now see what we have to do in custom selection listener, first invoke default selection listener EL (#{bindings.Departments1.collectionModel.makeCurrent}) to make selected row as current and then get current row from iterator as selected row is now current row
  See the managed bean code -



//Import these packages

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;

import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;

import oracle.jbo.Row;

import org.apache.myfaces.trinidad.event.SelectionEvent;   


 /**
     * Programmatic invocation of a method that an EL evaluates to.
     *
     * @param el EL of the method to invoke
     * @param paramTypes Array of Class defining the types of the parameters
     * @param params Array of Object defining the values of the parametrs
     * @return Object that the method returns
     */
    public static Object invokeEL(String el, Class[] paramTypes, Object[] params) {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        ELContext elContext = facesContext.getELContext();
        ExpressionFactory expressionFactory = facesContext.getApplication().getExpressionFactory();
        MethodExpression exp = expressionFactory.createMethodExpression(elContext, el, Object.class, paramTypes);

        return exp.invoke(elContext, params);
    }

    /**
     * Programmatic evaluation of EL.
     *
     * @param el EL to evaluate
     * @return Result of the evaluation
     */
    public static Object evaluateEL(String el) {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        ELContext elContext = facesContext.getELContext();
        ExpressionFactory expressionFactory = facesContext.getApplication().getExpressionFactory();
        ValueExpression exp = expressionFactory.createValueExpression(elContext, el, Object.class);

        return exp.getValue(elContext);
    }

    /**Custome Selection Listener for af:listView
     * @param selectionEvent
     */
    public void listSelectionListener(SelectionEvent selectionEvent) {
        //invoke this EL to set selected row as current row, if it is not invoked then first row will be current row
        invokeEL("#{bindings.Departments1.collectionModel.makeCurrent}", new Class[] { SelectionEvent.class }, new Object[] {
                 selectionEvent });
        // get the selected row , by this you can get any attribute of that row
        Row selectedRow = (Row) evaluateEL("#{bindings.Departments1Iterator.currentRow}");
        FacesMessage msg = new FacesMessage(selectedRow.getAttribute("DepartmentName").toString());
        msg.setSeverity(FacesMessage.SEVERITY_INFO);
        FacesContext.getCurrentInstance().addMessage(null, msg);
    }



• Now run application and check

Download Sample ADF Application here
Thanks , Happy Learning :)

Invoke ADF Table Selection Listener, custom selection listener for af:table

Sometimes we need to define our own selection listener for adf table, or we have to perform some operation on row selection in af:table.

We can do this by defining custom selection listener for table in Managed bean.
In this tutorial i am showing a popup on table row selection , Here i am using Employees table of HR Schema

• Prepare model and ViewController for Employees table and drag table in your page. Now select table and go to property Inspector , you will see its default selection listener 

• Now define your own (custom) selection listener for this table in your managed bean

• Now write this code snippet on that custom selection listener,this code invokes its default listener and get the selected row. first you have to invoke its default listener that is

#{bindings.Employees1.collectionModel.makeCurrent}

    public void empTableSelectionListener(SelectionEvent selectionEvent) {
        ADFUtil.invokeEL("#{bindings.Employees1.collectionModel.makeCurrent}", new Class[] {SelectionEvent.class},
                         new Object[] { selectionEvent });
        // get the selected row , by this you can get any attribute of that row
        Row selectedRow =
            (Row)ADFUtil.evaluateEL("#{bindings.Employees1Iterator.currentRow}"); // get the current selected row
        //to show popup, you can write your logic here , what you wanna do
        showPopup(empPopup, true);
    }

• you have to import these packages in order to invoke selection listener

import org.apache.myfaces.trinidad.event.SelectionEvent;
import org.apache.myfaces.trinidad.render.ExtendedRenderKitService;
import org.apache.myfaces.trinidad.util.Service;

• In above code snippet ADFUtil is an utility class that contains methods for invoking EL (Expression language), so you have to make a Java class named ADFUtil in same package as bean

import java.util.Map;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;

import javax.faces.context.FacesContext;

import oracle.adf.model.BindingContext;
import oracle.adf.model.DataControlFrame;


/**
 * Provides various utility methods that are handy to
 * have around when working with ADF.
 */
public class ADFUtil {

/**
* When a bounded task flow manages a transaction (marked as requires-transaction,.
* requires-new-transaction, or requires-existing-transaction), then the
* task flow must issue any commits or rollbacks that are needed. This is
* essentially to keep the state of the transaction that the task flow understands
* in synch with the state of the transaction in the ADFbc layer.
*
* Use this method to issue a commit in the middle of a task flow while staying
* in the task flow.
*/
public static void saveAndContinue() {
Map sessionMap =
FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
BindingContext context =
(BindingContext)sessionMap.get(BindingContext.CONTEXT_ID);
String currentFrameName = context.getCurrentDataControlFrame();
DataControlFrame dcFrame =
context.findDataControlFrame(currentFrameName);

dcFrame.commit();
dcFrame.beginTransaction(null);
}

/**
* Programmatic evaluation of EL.
*
* @param el EL to evaluate
* @return Result of the evaluation
*/
public static Object evaluateEL(String el) {
FacesContext facesContext = FacesContext.getCurrentInstance();
ELContext elContext = facesContext.getELContext();
ExpressionFactory expressionFactory =
facesContext.getApplication().getExpressionFactory();
ValueExpression exp =
expressionFactory.createValueExpression(elContext, el,
Object.class);

return exp.getValue(elContext);
}

/**
* Programmatic invocation of a method that an EL evaluates to.
* The method must not take any parameters.
*
* @param el EL of the method to invoke
* @return Object that the method returns
*/
public static Object invokeEL(String el) {
return invokeEL(el, new Class[0], new Object[0]);
}

/**
* Programmatic invocation of a method that an EL evaluates to.
*
* @param el EL of the method to invoke
* @param paramTypes Array of Class defining the types of the parameters
* @param params Array of Object defining the values of the parametrs
* @return Object that the method returns
*/
public static Object invokeEL(String el, Class[] paramTypes,
Object[] params) {
FacesContext facesContext = FacesContext.getCurrentInstance();
ELContext elContext = facesContext.getELContext();
ExpressionFactory expressionFactory =
facesContext.getApplication().getExpressionFactory();
MethodExpression exp =
expressionFactory.createMethodExpression(elContext, el,
Object.class, paramTypes);

return exp.invoke(elContext, params);
}

/**
* Sets a value into an EL object. Provides similar functionality to
* the <af:setActionListener> tag, except the from is
* not an EL. You can get similar behavior by using the following...

* setEL(to, evaluateEL(from))
*
* @param el EL object to assign a value
* @param val Value to assign
*/
public static void setEL(String el, Object val) {
FacesContext facesContext = FacesContext.getCurrentInstance();
ELContext elContext = facesContext.getELContext();
ExpressionFactory expressionFactory =
facesContext.getApplication().getExpressionFactory();
ValueExpression exp =
expressionFactory.createValueExpression(elContext, el,
Object.class);

exp.setValue(elContext, val);
}
}