Hey Jon!
I also think that this is a great idea :)
What i dont like about your approach is that it always creates a session.
> String vSessionId =
> ((HttpServletRequest)request).getSession(true).getId();
> Session vSession = (Session)request.getAttribute(vSessionId);
Why did you do it this way? Is it not ok to use a string constant as
attribute name?
I think my approach will be to open the session in the controller, and close
it only in the filter, if there is an open session.
regards
chris
----- Original Message -----
From: "Jon Lipsky" <[EMAIL PROTECTED]>
To: "Christoph Sturm" <[EMAIL PROTECTED]>; "Brad Clow"
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Tuesday, August 27, 2002 11:46 AM
Subject: Re: [Hibernate-devel] mvc & lazy loading
> Hi All,
>
> I use a Filter (a new addition in the 2.3 servlet spec) to open and close
my
> Hibernate sessions. By doing it this way it doesn't matter if I am using
> Velocity or JSP or something else to access Hibernate. As far as the
"view"
> is concerned the Hibernate session just exists, and only the Filter has to
> worry about opening and closing it.
>
> I was looking at the examples inclued with Hibernate and I was thinking
that
> maybe an example should be added of using a Filter since it's a good way
to
> cleanly seperate the creation and closing of the sessions for a web
> application.
>
> Jon...
>
> PS - Here is a code snippet to get you started if you want to do it this
> way:
>
> package example;
>
> import cirrus.hibernate.Datastore;
> import cirrus.hibernate.Session;
> import cirrus.hibernate.SessionFactory;
> import cirrus.hibernate.Hibernate;
>
> import javax.servlet.*;
> import javax.servlet.http.HttpServletRequest;
> import java.io.IOException;
>
> public class HibernateFilter implements Filter
> {
> static org.apache.log4j.Category log =
> org.apache.log4j.Category.getInstance(HibernateFilter.class.getName());
>
> private Datastore datastore;
> private SessionFactory sessions;
>
> public void doFilter(ServletRequest request, ServletResponse response,
> FilterChain chain) throws IOException, ServletException
> {
> try
> {
> // Get the http session id from the request, then we will try to get
the
> Hiberate
> // Session from the request. If it doesn't exist, then we will create
> it, otherwise
> // we will use the one that already exists.
> String vSessionId =
> ((HttpServletRequest)request).getSession(true).getId();
> Session vSession = (Session)request.getAttribute(vSessionId);
>
> if (vSession == null)
> {
> vSession = sessions.openSession();
> request.setAttribute(vSessionId, vSession);
>
> if (log.isDebugEnabled())
> {
> log.debug("Opened hibernate session.");
> }
> }
> }
> catch (Exception exc)
> {
> log.error("Error opening Hibernate session.", exc);
> }
>
> try
> {
> chain.doFilter(request, response);
> }
> finally
> {
> try
> {
> String vSessionId =
((HttpServletRequest)request).getSession().getId();
> Session vSession = (Session)request.getAttribute(vSessionId);
>
> // Only try to close the connection if it is open, since it might have
> been
> // closed somewhere else by mistake.
> if (vSession.isOpen())
> {
> vSession.close();
>
> if (log.isDebugEnabled())
> {
> log.debug("Closed hibernate session.");
> }
> }
> }
> catch (Exception exc)
> {
> log.error("Error closing Hibernate session.", exc);
> }
> }
> }
>
> public void init(FilterConfig aConfig) throws ServletException
> {
> // Initialize your datastore
> datastore = Hibernate.createDatastore();
>
> // Initialize your the object -> db mappings
> // ...
>
> // Initialize your session
> sessions = datastore.buildSessionFactory();
> }
>
> public void destroy()
> {
>
> }
> }
>
>
>
> ----- Original Message -----
> From: "Christoph Sturm" <[EMAIL PROTECTED]>
> To: "Brad Clow" <[EMAIL PROTECTED]>;
> <[EMAIL PROTECTED]>
> Sent: Tuesday, August 27, 2002 10:47 AM
> Subject: Re: [Hibernate-devel] mvc & lazy loading
>
>
> > Hi Brad!
> >
> > This subject is an interesting one that I was also thinking of lately.
> > I did a test app with maverick (mav.sourceforge.net), and there it was
> > really easy. If the controller(=model) implements ModelLifetime, a
discard
> > function is called when the views are finished and the model is
discarded.
> > There I closed my session. Other frameworks that just forward to the
view
> > dont offer this functionality.
> > For most of my stuff I use webwork, so I'd like a solution that works
> there
> > too. I was thinking of closing the session in the finalize method of my
> > controller, but then I dont really know when the session will be closed.
> > Another possibility would be to to pass the session to velocity, and
close
> > it in the velocity view servlet after all is rendered.
> >
> > How did you implement it?
> >
> > regards
> > chris
> > ----- Original Message -----
> > From: "Brad Clow" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Tuesday, August 27, 2002 12:38 AM
> > Subject: [Hibernate-devel] mvc & lazy loading
> >
> >
> > >
> > > to date, we have avoided using lazy loading when writing a web app in
> > > one of the standard mvc type frameworks (eg. struts, webwork, etc).
> > > this is because objects r typically retrieved, placed in the request
> > > attributes, session closed and control is then passed to the view
(JSP,
> > > velocity, etc). if the view attempts to access a lazy loaded
collection
> > > in one of the objects an exception is thrown as the associated session
> > > is closed.
> > >
> > > what do other people do?
> > >
> > > yesterday, i spent a few hours writing a very simple webapp framework
> > > that uses velocity for the view. it enables the velocity rendering to
> > > be done while a session is open. so far this is working quite well
for
> > > us.
> > >
> > > comments?
> > >
> > > brad
> > >
> > > > _______________________________
> > > > brad clow
> > > > chief technical officer
> > > > workingmouse
> > > >
> > > > email: [EMAIL PROTECTED]
> > > > web: http://www.workingmouse.com
> > > >
> > >
> > >
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