Programmatically add ajax behavior to SelectCheckboxMenu

How to add an ajax behavior to PrimeFaces SelectCheckboxMenu programmatically

You can find a simple example for SelectCheckboxMenu here and see how it looks like

Import required libraries

import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.faces.application.Application;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.component.html.HtmlPanelGrid;
import javax.faces.context.FacesContext;
import javax.faces.event.AjaxBehaviorEvent;
import javax.faces.event.BehaviorEvent;

import org.primefaces.component.behavior.ajax.AjaxBehavior;
import org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl;
import org.primefaces.component.message.Message;
import org.primefaces.component.outputlabel.OutputLabel;
import org.primefaces.component.outputpanel.OutputPanel;
import org.primefaces.component.selectcheckboxmenu.SelectCheckboxMenu;
import org.primefaces.event.ToggleSelectEvent;

Generate SelectCheckboxMenu and AjaxBehaviors dynamically

 in the following code snippet you can find code examples regarding :

  • getting a component from xhtml page 
  • making a new jsf component
  • adding value expression into a component
  • generating method expression and join an ajax behavior to a component
  • adding a new component into the page


..
FacesContext facesContext = FacesContext.getCurrentInstance();
Application app = FacesContext.getCurrentInstance().getApplication();

// find a panel grid in xhtml file  
UIViewRoot root = facesContext.getViewRoot();
HtmlPanelGrid panelGrid = (HtmlPanelGrid) root.findComponent("form:myPanel");

// create HtmlSelectManyCheckbox
// in PrimeFaces there is an implementation for this component, SelectCheckboxMenu
SelectCheckboxMenu scm = (SelectCheckboxMenu) app
  .createComponent(SelectCheckboxMenu.COMPONENT_TYPE);
String scmId = "scmId";
scm.setId(scmId);

// add a value expression into SelectCheckboxMenu
String valueExpressionParamater = "test value";
ValueExpression valueExForScm = app.getExpressionFactory().createValueExpression(
  facesContext.getELContext(), "#{myBean.myMethod('" + valueExpressionParamater + "')}",
  Object.class);
scm.setValueExpression("value", valueExForScm);

// filtered mode
scm.setFilter(true);
scm.setFilterMatchMode("startsWith");
scm.setLabel("You can change label initially");

// prepare and add a method expression for toggleSelect method
MethodExpression methodExpression = app.getExpressionFactory().createMethodExpression(
  facesContext.getELContext(), "#{myBean.populateLabelOnToggleSelect}", null,
  new Class<?>[] { BehaviorEvent.class });
AjaxBehavior ajaxBehavior = (AjaxBehavior) facesContext.getApplication().createBehavior(
  AjaxBehavior.BEHAVIOR_ID);
ajaxBehavior.setUpdate("@this");
ajaxBehavior.setProcess("@this");
ajaxBehavior.addAjaxBehaviorListener(new AjaxBehaviorListenerImpl(methodExpression,
  methodExpression));
scm.addClientBehavior("toggleSelect", ajaxBehavior);

// prepare and add a method expression for change method
methodExpression = app.getExpressionFactory().createMethodExpression(facesContext.getELContext(), "#{myBean.populateLabelOnChange}", null,
  new Class<?>[] { BehaviorEvent.class });
ajaxBehavior = (AjaxBehavior) facesContext.getApplication().createBehavior(
  AjaxBehavior.BEHAVIOR_ID);
ajaxBehavior.setUpdate("@this");
ajaxBehavior.setProcess("@this");
ajaxBehavior.addAjaxBehaviorListener(new AjaxBehaviorListenerImpl(methodExpression,
  methodExpression));
scm.addClientBehavior("toggleSelect", ajaxBehavior);

// make an output label
OutputLabel outputLabel = (OutputLabel) app.createComponent(OutputLabel.COMPONENT_TYPE);
outputLabel.setValue("this caption initially overrides scm caption");
outputLabel.setFor(scmId);

// generate panel add components into it
OutputPanel panel = (OutputPanel) app.createComponent(OutputPanel.COMPONENT_TYPE);
Message message = (Message) app.createComponent(Message.COMPONENT_TYPE);
message.setFor(scmId);
panel.getChildren().add(scm);
panel.getChildren().add(message);

// add components into panel grid
panelGrid.getChildren().add(outputLabel);
panelGrid.getChildren().add(panel);


..





The following are bean methods called from ajax behaviors












public void populateLabelOnChange(AjaxBehaviorEvent event) {
 SelectCheckboxMenu scm = (SelectCheckboxMenu) event.getComponent();
 scm.setLabel("A new label set on change method");
}

public void populateLabelOnToggleSelect(ToggleSelectEvent event) {
 SelectCheckboxMenu scm = (SelectCheckboxMenu) event.getComponent();
 Object[] values = (Object[]) scm.getSubmittedValue();
 scm.setLabel(values.length + " items selected");
}






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