C[omp]ute

From: "andrew cooke" <andrew@...>

Date: Sat, 25 Feb 2006 23:04:26 -0300 (CLST)

I've been reworking the form handling in the ol' Secret Project.  Below is
the handler for a page with two states ("simple" and "editing").  In the
"editing" state you can alter various fields.  The form fields are a
values in a bean (the Model), the JSP page contains the necessary to logic
to display the fields appropriately (the View), and below is the
Controller.

Obviously a lot of work is handled by sub-classes.  What's nice is that
it's generic.  Only the logic below is specific to this form:
 - reading / saving to the database
 - restricting editing to the "editing" state

The switching between states is via submit buttons, with names of the form
"action:xxx:path".  The xxx results in a call to setXxx(model) in the
action bean, where "path" is available in the action bean's scope and
identifies the appropriate information in the model.

So, for example, "action:delete:user.name" would call setDelete(model)
which would delete the user's name from the underlying model (via Java
Bean conventions / reflection).

public class IndexController extends BaseController {

  /**
   * Available bean modes
   */
  private static final String SIMPLE = "simple";
  private static final String EDITING = "editing";
  private static final SetEnum modes = new SetEnum().
  register(SIMPLE).
  register(EDITING);

  private InfoDao infoDao;

  public void setInfoDao(InfoDao infoDao) {
    this.infoDao = infoDao;
  }

  public InfoDao getInfoDao() {
    return infoDao;
  }

  @Override
  protected FormDisplayable newFormBean(HttpServletRequest req) {
    Info info = getInfoDao().getInfo(getViewer(), getOwner(req));
    info._setMembers(modes);
    info._setMode(SIMPLE);
    info.getDescription()._setMode(
        info.isMutable() ?
            FieldDisplayMode.EDITABLE
            : FieldDisplayMode.READONLY);
    logger.debug("new form bean: " + info);
    return info;
  }

  @Override
  protected Object newActionBean(HttpServletRequest req) {
    return new ActionBean(req);
  }

  public class ActionBean extends BaseActionBean {

    public ActionBean(HttpServletRequest req) {super(req);}

    @Override
    public void setEdit(FormDisplayable bean)
    throws Exception {
      super.setEdit(bean);
      bean._setMode(EDITING);
    }

    public void setSave(FormDisplayable bean)
    throws Exception {
      check(bean.isMode(EDITING),
          "can only save edited beans");
      getInfoDao().save((Info)bean);
      setInit(bean);
    }

  }

}

Andrew