Dependent dropdowns in Seam and Richfaces

Published Friday, April 17th, 2009 by AN

It is not uncommon to want to make a combobox with choices that depend on another combobox. But it often seems very complicated to actually do this. So here is a piece of example code that I use with Seam and Richfaces. Imagine we have different vendors Vendors each with different Models of something.

The somewhat large blurb of Richfaces markup is to make two ordinary input textfields feel like two ajaxy comboboxes. It sucks a bit, but on the other hand the Java code is nice and clean.

How do you make dependent gui elements?

xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:s="http://jboss.com/products/seam/taglib"
xmlns:rich="http://richfaces.org/rich"
xmlns:a4j="http://richfaces.org/a4j">
<div class="dialog">
Vendor</div>
<div class="dialog">
Model

<br class="clear" /></div>

package test;

import java.util.ArrayList;
import java.util.List;

import javax.ejb.Remove;
import javax.ejb.Stateful;

import org.jboss.labs.seam.guice.Guice;
import org.jboss.seam.ScopeType;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Out;
import org.jboss.seam.annotations.Scope;
import org.jboss.seam.log.Log;

import com.google.inject.Inject;

import dk.telenor.tacs.api.DBApi;
import dk.telenor.tacs.db.Model;
import dk.telenor.tacs.db.Vendor;

@Stateful
@Scope(ScopeType.SESSION)
@Name("vendormodelselector")
@Guice
public class VendorModelSelectorBeanImpl implements VendorModelSelectorBean {

@Inject	private DBApi dbApi;

@Out(required = false, value="model")
private Model model = new Model();

@Out(required = false, value="vendor")
private Vendor vendor = new Vendor();

public List autocompleteVendor(){
return dbApi.getMatches(new Vendor());
}

public List autocompleteModel(){
if (vendor == null || vendor.getName() == null) {
return new ArrayList();
}
return dbApi.getMatches( new Model(vendor, null) );
}

public void setVendor(final Vendor vendor){
this.vendor = vendor;
}

public void setModel(final Model Model){
this.model = model;
}

public Model getModel(){
return model;
}

public boolean isReady(){
return model.getId() != null;
}

@Remove
public void destroy(){}
}

Tags: Java, Richfaces, Seam
Posted in Techchat

This entry was posted on Friday, April 17th, 2009 at 11:45 am and is filed under Techchat. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.