Don't persist UIComponent state, now with attributes!

In this blogpost I showed how to disable the persistence of a UIComponent, but it was needed to write Java code to check for the specific component and change. In this blog entry I will show a more generic way to do this, with the attribute tag.

On the showDetailItem we define an attribute with a name and value:

The Java code for the addComponentChange method in the PortalComposerChangeManager now looks like this:

  public void addComponentChange(FacesContext context, UIComponent component,
                                 ComponentChange change)
  {
    Map attrs = component.getAttributes();
    String value = (String) attrs.get(NON_PERSIST_STRING);

    if (value != null)
    {
      logger.fine("NonPersist attribute found, we don't persist!");
      return;
    }
    super.addComponentChange(context, component, change);
  }

I defined a static final NON_PERSIST_STRING with the value "nonPersist", like the name of the attribute. If the attribute is found, we don't persist the componentChange.
If you want a more specific approach, you can still check for a specific ComponentChange, in the case of this example, we still check if the ComponentChange matches the value in the attribute (disclosed):

  public void addComponentChange(FacesContext context, UIComponent component,
                                  ComponentChange change)
  {
    Map attrs = component.getAttributes();
    String value = (String) attrs.get(NON_PERSIST_STRING);

    if (value != null)
    {
      if (change instanceof AttributeComponentChange &&
          value.equals(((AttributeComponentChange) change).getAttributeName()))
      { //we check if the attribute value equals the change.
        logger.fine("{0} attribute found; {1} event on {2}, we don’t persist.", new Object[]
            { NON_PERSIST_STRING, value, component.getClass() });
        return;
      }
    }
    super.addComponentChange(context, component, change);
  }

This code can be expanded or changed to check for specific changes according to your needs.
I uploaded a new workspace here, so you can download and browse the source if you want to.