This post originated from an RSS feed registered with Agile Buzz by Dominik Wei-Fieg. Original Post: How to make JSF navigation rules more dynamic Feed Title: Ars Subtilior Feed URL: http://typo.ars-subtilior.com/articles.rss Feed Description: Finest Handmade Code Random thoughts about agile software development as an art Latest Agile Buzz Posts Latest Agile Buzz Posts by Dominik Wei-Fieg Latest Posts From Ars Subtilior

Consider the following situation:

You do a post request from some form in an JSF application and want to decide on the page to redirect to dynamically. No problem, just use different “navigation-case” entries and go to different “to-view-id”s depending on the “from-outcome”.

<navigation-rule>
    <from-view-id>/pages/organisation/*</from-view-id>
    <navigation-case>
        <from-action>#{OrganisationBean.select}</from-action>
        <from-outcome>to-user</from-outcome>
        <to-view-id>/pages/user/details.jsf</to-view-id>
        <redirect/>
    </navigation-case>
    <navigation-case>
        <from-action>#{OrganisationBean.select}</from-action>
        <from-outcome>to-project</from-outcome>
        <to-view-id>/pages/project/details.jsf</to-view-id>
        <redirect/>
    </navigation-case>
    <navigation-case>
        <from-action>#{OrganisationBean.select}</from-action>
        <from-outcome>to-whatever</from-outcome>
        <to-view-id>/pages/whatever/details.jsf</to-view-id>
        <redirect/>
    </navigation-case>
</navigation-rule>

Sure, this works. It’s not exactly what I would call DRY, but it works. But what if you need to be more dynamic then that?

Just use a framework that’s more dynamic I hear you say.

Sure, I’d love to. But what if that is not an option?

I found this, this and this on the web, and putting these together gave me the following solution which I wanted to share with you:

Step 1:

Create a ViewHandler, in my case a subclass of com.sun.facelets.FaceletViewHandler and overwrite getActionURL():

@Override public String getActionURL(FacesContext context, String viewId) { String result = viewId; if(Util.isVBExpression(viewId)) { ValueBinding vb = context.getApplication().createValueBinding(viewId); result = vb.getValue(context).toString(); } return super.getActionURL(context, result); }

This enables you to use EL in the to-view-id entry of a navigation case.

Step 2:

Register your view handler with the application, in my case:

<application>
    ...
    <view-handler>com.interactive_objects.jsf.crud.generic.DynamicViewHandler</view-handler>
</application>

Step 3:

Now you can do things like:

<navigation-rule>
    <from-view-id>/pages/organisation/*</from-view-id>
    <navigation-case>
        <from-action>#{OrganisationBean.select}</from-action>
        <from-outcome>selected</from-outcome>
        <to-view-id>#{OrgansiationBean.computedRedirect}</to-view-id>
        <redirect/>
    </navigation-case>
</navigation-rule>

(You can also use compound expressions like “/path/to/page.jsf?foo=#{ManagedBean.bar}”).

String value=result;

result= getActionURL(...