hibernate-devel — development

Re: [Hibernate-devel] mvc & lazy loading

[Christoph S. <ch...@mc...>]

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" <jon...@xe...>
To: "Christoph Sturm" <ch...@mc...>; "Brad Clow"
<bra...@wo...>; <hib...@li...>
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" <ch...@mc...>
> To: "Brad Clow" <bra...@wo...>;
> <hib...@li...>
> 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" <bra...@wo...>
> > To: <hib...@li...>
> > 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: bra...@wo...
> > > > web:   http://www.workingmouse.com
> > > >
> > >
> > >
> > > -------------------------------------------------------
> > > This sf.net email is sponsored by: OSDN - Tired of that same old
> > > cell phone?  Get a new here for FREE!
> > >
> >
>
https://www.inphonic.com/r.asp?r____________________________________________
> > ___
> > > Hibernate-devel mailing list
> > > Hib...@li...
> > > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> > >
> >
> >
> >
> > -------------------------------------------------------
> > This sf.net email is sponsored by: OSDN - Tired of that same old
> > cell phone?  Get a new here for FREE!
> > https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> > _______________________________________________
> > Hibernate-devel mailing list
> > Hib...@li...
> > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> >
>
>
>
> -------------------------------------------------------
> This sf.net email is sponsored by: OSDN - Tired of that same old
> cell phone?  Get a new here for FREE!
> https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> _______________________________________________
> Hibernate-devel mailing list
> Hib...@li...
> https://lists.sourceforge.net/lists/listinfo/hibernate-devel
>

Re: [Hibernate-devel] mvc & lazy loading

[Jon L. <jon...@xe...>]

Brad,

This is exactly what I do...  I also have a couple different versions of my
filter that handler their own URL filtering using the Apache ORO library.  I
do this so I can more complex regular expressions for the the URL
matching...

Jon...
----- Original Message -----
From: "Brad Clow" <bra...@wo...>
To: <hib...@li...>
Sent: Saturday, August 31, 2002 7:38 AM
Subject: Re: [Hibernate-devel] mvc & lazy loading


> jon,
>
> this seems like a pretty neat way of doing it.  do u use <filter-mapping>
> elements in the web.xml to control which requests it gets applied to - so
u
> only have a session created for requests that actually need one?
>
> brad
>
>
> ----- Original Message -----
> From: "Jon Lipsky" <jon...@xe...>
> To: "Christoph Sturm" <ch...@mc...>; "Brad Clow"
> <bra...@wo...>; <hib...@li...>
> Sent: Tuesday, August 27, 2002 7:46 PM
> 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" <ch...@mc...>
> > To: "Brad Clow" <bra...@wo...>;
> > <hib...@li...>
> > 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" <bra...@wo...>
> > > To: <hib...@li...>
> > > 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: bra...@wo...
> > > > > web:   http://www.workingmouse.com
> > > > >
> > > >
> > > >
> > > > -------------------------------------------------------
> > > > This sf.net email is sponsored by: OSDN - Tired of that same old
> > > > cell phone?  Get a new here for FREE!
> > > >
> > >
> >
>
https://www.inphonic.com/r.asp?r____________________________________________
> > > ___
> > > > Hibernate-devel mailing list
> > > > Hib...@li...
> > > > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> > > >
> > >
> > >
> > >
> > > -------------------------------------------------------
> > > This sf.net email is sponsored by: OSDN - Tired of that same old
> > > cell phone?  Get a new here for FREE!
> > > https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> > > _______________________________________________
> > > Hibernate-devel mailing list
> > > Hib...@li...
> > > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> > >
> >
> >
>
>
>
> -------------------------------------------------------
> This sf.net email is sponsored by: OSDN - Tired of that same old
> cell phone?  Get a new here for FREE!
> https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> _______________________________________________
> Hibernate-devel mailing list
> Hib...@li...
> https://lists.sourceforge.net/lists/listinfo/hibernate-devel
>

Re: [Hibernate-devel] Changes

[Brad C. <bra...@wo...>]

hibernate.org.au is available.

brad

----- Original Message -----
From: <Gavin_King/Cirrus%CI...@ci...>
To: <hib...@li...>
Sent: Monday, September 02, 2002 7:07 PM
Subject: [Hibernate-devel] Changes


>
> As of this week, I am no longer working for Cirrus Technologies. This
> should have no particular effect upon development of Hibernate, however. I
> will be taking a shortish break from work (but not from Hibernate) before
I
> start looking for a new job. (I've been needing a break and a change for a
> while now.)
>
> At some stage I plan to register a domain name for the project and then
> rename packages along Java standard naming conventions. I hadn't done this
> previously because all the obvious URLs were unavailable. So if anyone can
> think of an available domain that would look better than
"cirrus.hibernate"
> at the top of their code, suggestions are very welcome :)
>
> Gavin
>
> P.S. I will let everyone know my new email address as soon as I can find
> something..... (oh, if anyone with a mail server wants to donate a couple
> of email addresses to the project, that would be very nice....)
>
>
>
>
> -------------------------------------------------------
> This sf.net email is sponsored by: OSDN - Tired of that same old
> cell phone?  Get a new here for FREE!
> https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> _______________________________________________
> Hibernate-devel mailing list
> Hib...@li...
> https://lists.sourceforge.net/lists/listinfo/hibernate-devel
>

[Hibernate-devel] Changes

[Gavin_King/Cirrus%<CI...@ci...>]

As of this week, I am no longer working for Cirrus Technologies. This
should have no particular effect upon development of Hibernate, however. I
will be taking a shortish break from work (but not from Hibernate) before I
start looking for a new job. (I've been needing a break and a change for a
while now.)

At some stage I plan to register a domain name for the project and then
rename packages along Java standard naming conventions. I hadn't done this
previously because all the obvious URLs were unavailable. So if anyone can
think of an available domain that would look better than "cirrus.hibernate"
at the top of their code, suggestions are very welcome :)

Gavin

P.S. I will let everyone know my new email address as soon as I can find
something..... (oh, if anyone with a mail server wants to donate a couple
of email addresses to the project, that would be very nice....)

RE: [Hibernate-devel] Validation interface?

[Anton v. S. <an...@ap...>]

> Would anyone have a use for a new callback interface
>
> public interface Validatable {
>   public void validate() throws ValidationException;
> }
>
> that would be called just before saving or updating an object's state?

Yes, I would.  I used something virtually identical in my home-grown
persistence code, before switching to Hibernate, and found it very useful.

> (Remember, i'm trying to avoid turning Hibernate into a framework.)

I think as long as things like this are small, low-overhead, optional, and
useful, they're good.  This one seems to qualify...

Anton

[Hibernate-devel] Validation interface?

[Gavin_King/Cirrus%<CI...@ci...>]

Would anyone have a use for a new callback interface

public interface Validatable {
  public void validate() throws ValidationException;
}

that would be called just before saving or updating an object's state?

The object wouldn't be allowed to adjust it's own state from inside
validate(), just throw an exception if it's invariants were violated.

I've wondered about this a few times, but it never passed the bloat test
really.... (Remember, i'm trying to avoid turning Hibernate into a
framework.)


However, if its a thing that would be used its sooo easy to implement.

Re: [Hibernate-devel] Saving parent before children

[Gavin_King/Cirrus%<CI...@ci...>]

> Don't you mean the <one-to-one> element?

Of course.

> Is constrained="false" equivalent to the way it currently works (and I
> assume will remain the default)?

yes.

Re: [Hibernate-devel] Bug with discriminator-value?

[Gavin_King/Cirrus%<CI...@ci...>]

You need to specify a discriminator-value for the superclass.

The error message is confusing because, by default, Hibernate uses the
classname as the discriminator value (and string as the type).

[Hibernate-devel] Bug with discriminator-value?

[Mark W. <mor...@SM...>]

I seem to be having a problem with the <discriminator> element.  It 
works when the discriminator's type is "string," but not when it is 
"integer."  My mapping file looks like this:

<class name="Foo" table="Foo">
  <id name="accessionId" column="fooId">
    <generator class="assigned" />
  </id>
  <discriminator column="fooType" type="integer" />
  <subclass name="FooA" discriminator-value="1">
    <property name="a" />
  </subclass>
  <subclass name="FooB" discriminator-value="2">
    <property name="b" />
  </subclass>
  <subclass name="FooC" discriminator-value="3">
    <property name="c" />
  </subclass>
</class>

And I'm getting the following error:

Sep 1, 2002 1:42:39 PM cirrus.hibernate.helpers.XMLHelper parseInputSource
INFO: Parsing XML: unknown system id
Sep 1, 2002 1:42:39 PM cirrus.hibernate.Environment <clinit>
INFO: loaded properties from resource hibernate.properties
Sep 1, 2002 1:42:39 PM cirrus.hibernate.Environment <clinit>
INFO: echoing all SQL to stdout
Sep 1, 2002 1:42:39 PM cirrus.hibernate.Environment <clinit>
INFO: using java.io streams to persist binary types
Sep 1, 2002 1:42:39 PM cirrus.hibernate.Environment <clinit>
INFO: JVM proxy support: true
Sep 1, 2002 1:42:39 PM cirrus.hibernate.sql.Dialect <init>
INFO: Using dialect: class cirrus.hibernate.sql.OracleDialect
Sep 1, 2002 1:42:39 PM 
cirrus.hibernate.connection.DriverManagerConnectionProvider configure
INFO: Hibernate connection pool size: 5
Sep 1, 2002 1:42:39 PM 
cirrus.hibernate.connection.DriverManagerConnectionProvider configure
INFO: JDBC isolation level: 2
Sep 1, 2002 1:42:39 PM 
cirrus.hibernate.connection.DriverManagerConnectionProvider configure
INFO: Using driver: oracle.jdbc.driver.OracleDriver at URL: 
jdbc:oracle:thin:@localhost:1521:DEV
Sep 1, 2002 1:42:39 PM 
cirrus.hibernate.connection.DriverManagerConnectionProvider configure
INFO: Connection properties: {user=woon, password=foo}
Sep 1, 2002 1:42:39 PM cirrus.hibernate.ps.PreparedStatementCache <init>
INFO: prepared statement cache size: 100
Sep 1, 2002 1:42:39 PM cirrus.hibernate.impl.SessionFactoryImpl <init>
INFO: Use outer join fetching: true
Sep 1, 2002 1:42:40 PM cirrus.hibernate.impl.SessionFactoryImpl <init>
INFO: Use scrollable result sets: true
Sep 1, 2002 1:42:40 PM cirrus.hibernate.impl.SessionFactoryImpl <init>
INFO: Use JDBC 2 batch updates: true

--> cirrus.hibernate.MappingException
--> Could not format discriminator value to SQL string: For input 
string: "Foo"
cirrus.hibernate.MappingException: Could not format discriminator value 
to SQL string: For input str
ing: "Foo"
        at 
cirrus.hibernate.impl.ClassPersister.<init>(ClassPersister.java:304)
        at 
cirrus.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:162)
        at 
cirrus.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:92)
        at 
cirrus.hibernate.impl.DatastoreImpl.buildSessionFactory(DatastoreImpl.java:60)
        at test.Hibernate.main(Hibernate.java:32)


When I change the discriminator type to a string, however, this will 
work perfectly fine...  This is with the latest CVS build.  Anyone else 
seeing this?

Thanks,
-Mark

Re: [Hibernate-devel] Saving parent before children

[Mark W. <mor...@SM...>]

Gavin_King/Cirrus%CI...@ci... wrote:

>This is now implemented as an optional attibute constrained="true|false" on
>the <one-to-many> element.
>

Don't you mean the <one-to-one> element?  Is constrained="false" 
equivalent to the way it currently works (and I assume will remain the 
default)?

Thanks,
-Mark

Re: [Hibernate-devel] Saving parent before children

[Gavin_King/Cirrus%<CI...@ci...>]

This is now implemented as an optional attibute constrained="true|false" on
the <one-to-many> element.

Re: [Hibernate-devel] mvc & lazy loading

[Brad C. <bra...@wo...>]

jon,

this seems like a pretty neat way of doing it.  do u use <filter-mapping>
elements in the web.xml to control which requests it gets applied to - so u
only have a session created for requests that actually need one?

brad


----- Original Message -----
From: "Jon Lipsky" <jon...@xe...>
To: "Christoph Sturm" <ch...@mc...>; "Brad Clow"
<bra...@wo...>; <hib...@li...>
Sent: Tuesday, August 27, 2002 7:46 PM
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" <ch...@mc...>
> To: "Brad Clow" <bra...@wo...>;
> <hib...@li...>
> 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" <bra...@wo...>
> > To: <hib...@li...>
> > 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: bra...@wo...
> > > > web:   http://www.workingmouse.com
> > > >
> > >
> > >
> > > -------------------------------------------------------
> > > This sf.net email is sponsored by: OSDN - Tired of that same old
> > > cell phone?  Get a new here for FREE!
> > >
> >
>
https://www.inphonic.com/r.asp?r____________________________________________
> > ___
> > > Hibernate-devel mailing list
> > > Hib...@li...
> > > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> > >
> >
> >
> >
> > -------------------------------------------------------
> > This sf.net email is sponsored by: OSDN - Tired of that same old
> > cell phone?  Get a new here for FREE!
> > https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> > _______________________________________________
> > Hibernate-devel mailing list
> > Hib...@li...
> > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> >
>
>

[Hibernate-devel] Re: mvc & lazy loading

[Brad C. <bra...@wo...>]

originally i wondered whether this would work as the struts action servlet
does a RequestDispatcher.forward to pass control to the resource specified
by the ActionForward resulting from an Action.  however, i did a quick
little test, and i think your solution would work. ideally though, u would
only want a session created if the processing of the request used hibernate.

brad

----- Original Message -----
From: "Colin Evans" <ce...@mo...>
To: <hib...@li...>; <bra...@wo...>
Sent: Wednesday, August 28, 2002 6:59 AM
Subject: Re: mvc & lazy loading


> Hi Brad,
>
> I haven't tried this yet, but if I wanted to use lazy loading with Struts,
I
> would probably override ActionServlet and do something like this, and have
> my DAO layer pull the session from the request context as needed:
>
> ----
> /**
>  * Hibernate Action Servlet
>  */
> public class HibernateActionServlet
>         extends ActionServlet
> {
>     public void service(HttpServletRequest request,
>                         HttpServletResponse response)
>     {
>         Session session = null;
>         try
>         {
>             session = factory.openSession();
>             request.setAttribute("session", session);
>             super.service(request, response);
>         }
>         finally
>         {
>            if(session != null) session.close();
>         }
>     }
> }
> ----
>
> Do other frameworks allow the controller servlet to be overridden?  This
> probably is a fairly straightforward way to get lazy loading working.
>
> -Colin
>
> --
> Colin Evans
> Mobilesys
> www.mobilesys.com
>

Re: [Hibernate-devel] Saving parent before children

[Gavin_King/Cirrus%<CI...@ci...>]

>That sounds perfect.  Any chance of this happening in the near future?
>I'm sort of at a dead end at the moment because of this.

Yeah, its easy enough to implement. I'll have a look at it today if you
like.


>I was hoping  to use the Lifecycle interface to get around this problem,
>but it looks like you only get callbacks before the event and not after
>the event. Have you considered extending Lifecycle to support this?

Its very difficult to strike a balance with the Lifecycle interface. Theres
all kind of events that could be useful but, on the other hand, we want the
interface to be as simple as possible and we don't want to let assumptions
about the internal dynamics of the session implementation "seep" into the
API. The other thing is that its very difficult to change callback
interfaces (you can deprecate methods but never add new ones).

So Hibernate tries to stay as far away as possible from these kind of
frameworky solutions to problems. I think its better to address this
particular issue as proposed....

Of course, I am very open to other people's opinions on this.

Re: [Hibernate-devel] Saving parent before children

[Mark W. <mor...@SM...>]

Gavin_King/Cirrus%CI...@ci... wrote:

>So we should add something like:
>
>  <one-to-one name="child" constrained="outward"/>
>
>and a matching
>
>  <one-to-one name="parent" constrained="inward"/>
>
>or something like that....
>  
>

That sounds perfect.  Any chance of this happening in the near future? 
 I'm sort of at a dead end at the moment because of this.  I was hoping 
to use the Lifecycle interface to get around this problem, but it looks 
like you only get callbacks before the event and not after the event. 
 Have you considered extending Lifecycle to support this?

Thanks,
-Mark

Re: [Hibernate-devel] Saving parent before children

[Gavin_King/Cirrus%<CI...@ci...>]

Yeah, this is interesting.

This problem is specific to one-to-one associations.

Firstly, yes there is a way, simply call save() for the parent before
calling save() for the children. Hibernate *always* inserts rows in the
same order the objects were saved.

However, there is a problem for saves cascaded through cascade="all". The
problem is that one-to-one associations are by nature bidirectional so in
the absence of any other metadata we wouldn't know whether the foreign key
was from "parent" to "child" or vice-versa. Currently Hibernate just treats
one-to-one associations like many-to-one (ie. assumes the foreign key runs
from "parent" to "child" and so inserts the child row first).

(Saves cascaded via Lifecycle callbacks could also suffer the same problem,
but theres not much we can do about that.)

In the case of many-to-one relationships, there is another trick used to
ensure no constraint violations occur, even in the case of circular foreign
key references. Hibernate is able to insert a null into the foreign key
column and then update it later. Unfortunately we can't use this technique
with one-to-ones because the foreign key constrains the primary keys.

So the general solution to this problem must involve adding an attribute to
the <one-to-one> element to tell Hibernate which direction the foreign key
constraint points and hence whether the association should be cascaded
before or after the parent is saved. (This would also let as create the
foreign key from the SchemaExport tool.)

So we should add something like:

  <one-to-one name="child" constrained="outward"/>

and a matching

  <one-to-one name="parent" constrained="inward"/>

or something like that....

Re: [Hibernate-devel] (no subject)

[Mark W. <mor...@SM...>]

Yaron Zakai wrote:

>Hi,
>
>  On an earlier post, Gavin proposed to follow my proposal and make an API
>modification 
> - there were no objections for that. 
>I would like to understand what is the next step. If there is an issue with
>implementing 
>the change, I hereby volunteer to implement it. Assuming I will make the
>modification soon, is there a chance to get it into 1.1?
>

Gavin already got to it!  Check out the latest beta (although I think he 
did it in b10).

-Mark

[Hibernate-devel] (no subject)

[Yaron Z. <ya...@id...>]

Hi,

  On an earlier post, Gavin proposed to follow my proposal and make an API
modification 
 - there were no objections for that. 
I would like to understand what is the next step. If there is an issue with
implementing 
the change, I hereby volunteer to implement it. Assuming I will make the
modification soon, is there a chance to get it into 1.1?

Thanks, Yaron.

----------------------------------------------------------------------------
-----------------------------
Quote from Gavin

http://sourceforge.net/forum/forum.php?thread_id=722838&forum_id=128638

Yaron Zakai makes a suggestion I quite like.

I've seen that new users often have trouble realizing they need to use
insert() instead of save() when they want to use application-assigned ids.
People seem to expect that the "assigned" id generator will just use the
existing id of an object when you call save().

Secondly, some people would like insert() to cascade to insert(). Whereas
other times insert() to save() is appropriate.

So I would like to deprecate the following methods:

  Session.insert(Object)
  Session.insert(Object, Serializable)

and add the following method

  Session.save(Object, Serializable)

(which does exactly what Session.insert(Object, Serializable) used to do.)

Then we would deprecate the IDGenerator interface and replace it with:

public interface IdentifierGenerator {
  public Serializable generate(SessionImplementor session, Object entity)
    throws ..... ;
}

[Hibernate-devel] Saving parent before children

[Mark W. <mor...@al...>]

Hi all...

Is there a way for Hibernate to persist the parent before any children? 
 I've an object Foo which has a child Bar, and the mapping looks like this:

<class name="Foo">
  <id name="id">
    <generator class="assigned" />
  </id>
  <one-to-one name="bar" class="Bar" />
</class>

<class name="Bar">
  <id name="id">
      <generator class="assigned" />
  </id>
</class>

I'm having problems because Bar's id must be a foreign key into Foo. 
 Because Bar gets created before Foo, I get a constraint violation.  Is 
there a way around this?  I suspect that this would also be necessary to 
support normalized mappings.

Thanks,
-Mark

[Hibernate-devel] Re: mvc & lazy loading

[Colin E. <ce...@mo...>]

Hi Brad,

I haven't tried this yet, but if I wanted to use lazy loading with Struts, I
would probably override ActionServlet and do something like this, and have
my DAO layer pull the session from the request context as needed:

----
/**
 * Hibernate Action Servlet
 */
public class HibernateActionServlet
        extends ActionServlet
{
    public void service(HttpServletRequest request, 
                        HttpServletResponse response)
    {
        Session session = null;
        try
        {
            session = factory.openSession();
            request.setAttribute("session", session);
            super.service(request, response);
        }
        finally
        {
           if(session != null) session.close();
        }
    }
}
----

Do other frameworks allow the controller servlet to be overridden?  This
probably is a fairly straightforward way to get lazy loading working.

-Colin

--
Colin Evans
Mobilesys 
www.mobilesys.com

[Hibernate-devel] (no subject)

[Lenny S. <lr...@fa...>]

[Hibernate-devel] (no subject)

[Lenny S. <lr...@fa...>]

Re: [Hibernate-devel] boolean basic type

[Gavin_King/Cirrus%<CI...@ci...>]

Depends upon the database. Check the source of the cirrus.hibernate.sql
package for the mapping for your particular dialect.

Please post these kind of questions in the user forum, rather than the
development mailing list.

Oh, and the bugfix you requested (update() for classes with no property
columns) is now in CVS....

peace

[Hibernate-devel] boolean basic type

[Mark W. <mor...@SM...>]

Hi all...

Can anyone tell me what Hibernate expects the db column type to be if I 
specify type="boolean" in the mapping file?

Thanks,
-Mark

Re: [Hibernate-devel] mvc & lazy loading

[Jon L. <jon...@xe...>]

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" <ch...@mc...>
To: "Brad Clow" <bra...@wo...>;
<hib...@li...>
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" <bra...@wo...>
> To: <hib...@li...>
> 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: bra...@wo...
> > > web:   http://www.workingmouse.com
> > >
> >
> >
> > -------------------------------------------------------
> > This sf.net email is sponsored by: OSDN - Tired of that same old
> > cell phone?  Get a new here for FREE!
> >
>
https://www.inphonic.com/r.asp?r____________________________________________
> ___
> > Hibernate-devel mailing list
> > Hib...@li...
> > https://lists.sourceforge.net/lists/listinfo/hibernate-devel
> >
>
>
>
> -------------------------------------------------------
> This sf.net email is sponsored by: OSDN - Tired of that same old
> cell phone?  Get a new here for FREE!
> https://www.inphonic.com/r.asp?r=sourceforge1&refcode1=vs3390
> _______________________________________________
> Hibernate-devel mailing list
> Hib...@li...
> https://lists.sourceforge.net/lists/listinfo/hibernate-devel
>