[Springframework-developer] Request and Session attributes in template based views

[Darren D. <da...@da...>]

A project of mine uses a servlet Filter to pre-process many http requests=
,
as a result of which objects are occasionally added to the user's
HttpSession or as request attributes.

I need these objects to be available in some views, regardless of which
controller eventually handled the request.  That's OK for JSP/JSTL and
even Spring's XSLT and Document based views that have access to them, but
awkward for Velocity/FreeMarker.  It's not difficult to extend these view=
s
to cope, but I wondered if it would be better as an addition to the
framework classes.

Two new bean properties would exist on VelocityView (also applies to
FreeMarkerView so possibly in a new AbstractTemplateView below
AbstractUrlBasedView)...

private boolean exposeRequestAttributes =3D false;
private boolean exposeSessionAttributes =3D false;
// corresponding public mutators omitted

The rendering methods can then use these properties to decide whether to
put request/session objects into the velocityContext or FreeMarker model.

There's obviously a good argument that says the controller is solely
responsible for deciding what ends up in the model, but the following
issues arise in that case:
  i. If a view currently takes advantage of having access to the
request/session, then switching view technologies to a template view is
impossible without amending controller code or specifying a
HandlerInterceptor to expose the same objects.
  ii. If a HandlerInterceptor is not used (potentially awkward to
configure)  then all controllers would potentially have to be modified
to cater for the requirement.  A common app-specific superclass would be
impossible if the behaviour was required from both FormControllers and
SimpleControllers

Thoughts?


--=20
Darren Davison
Public Key: http://www.davison.uk.net/key.jsp