An Introduction To JBoss RichFaces

Specific row update

Updating the whole table is rather simple. How do we update only the row that has been edited? All data components in RichFaces (including a4j:repeat) come with a feature that allows updating only a subset of rows. All such components expose an ajaxKeys attribute that points to the row or rows that need to be updated.

Let's first go over the changes we need to make on the page.
First, we need to set the ajaxKeys attribute on rich:dataTable (changes shown in bold):

<rich:dataTable value="#{userBean.users}" var="user" 
   ajaxKeys="#{userBean.rowsToUpdate}">

That's all we need to do with the table.

Next we need to call a save method from the modal panel when we make changes to the user information. The updated Save link will look like this:

<a4j:commandLink actionListener="#{userBean.save}"
      oncomplete="#{rich:component('useredit')}.hide()"
      reRender="name, email">
      Save
    </a4j:commandLink>

The actionListener points to a listener inside the managed bean which we are going to create next. We also have the reRender attribute pointing to columns in the table. Basically, to achieve partial table update, we need to specify two things. First, which columns to update. In our case we are updating the name and email columns. Second, we need to specify which rows to update. This is done via the ajaxKeys attribute which is bound to a Set object that holds row numbers to update.

Let's see what changes are need in the managed bean.

First, we need to create the Set object to hold rows to update:

private Set <Integer>rowsToUpdate;
public Set <Integer>getRowsToUpdate() {
 return rowsToUpdate;
}

Only a getter is needed for this property as this property will never be set from the page.

Next, we need the save() listener.

public void save (ActionEvent event) {
  
 rowsToUpdate.clear();
 rowsToUpdate.add(users.indexOf(selectedUser));
}

In the save listener, all we need is to save the row number of the user we are editing. 

Finally, we need to initialize rowsToUpdate property inside the init() method, right after we create the users:

rowsToUpdate =  new HashSet<Integer>(); 

The only other change we need is to add an a4j:keepAlive tag to the page. This is poor's man conversation scope (like in Seam). Basically, we need to keep the list of users alive for longer than a request and so a4j:keepAlive does just that. Right before the modal panel, add the following:

<a4j:keepAlive beanName="userBean"/>

Make sure everything is saved, redeploy, and run the application. You should now be able to open a modal panel, edit user information, and save the changes. When the changes are saved, only that particular row is updated.

Summary

I'm hoping this example showed you a little bit more than just Hello World. We have used a table component together with a modal panel. These are two components that very often used in real applications. I have also showed you how to edit a particular record inside a table via the modal panel and then only update that particular row. Of course, updating just a specific row is a feature of RichFaces data components.

To point out another thing, when we created an AJAX-based application here, we didn't have to deal with any JavaScript (well, besides the very simple client-side function available in RichFaces). RichFaces takes care of generating all the necessary (and usually quite complicated) JavaScript.

With RichFaces, you can continue using a JSF component-based approach, but with a large set of extra components to build applications with a rich user interface.

About the Author

Max Katz is a Senior Systems Engineer at Exadel. He has been helping customers jump-start their RIA development as well as providing mentoring, consulting, and training. Max is a recognized subject matter expert in the JSF developer community. He has provided JSF/RichFaces training for the past three years, presented at many conferences, and written several published articles on JSF-related topics. Max also leads Exadel's RIA strategy and writes about RIA technologies in his blog, http://mkblog.exadel.com. He is an author of Practical RichFaces book (Apress). Max holds a BS in computer science from the University of California, Davis.

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Article Resources: 

richfaces-template.zip