Sorry for the inaccurate info about Hibernate4Gwt, it's been a while
since I looked at it.
I would agree that depending on how you use Hibernate, the quick
solution may or may not work for you. While my objects are not always
fully populated on the server, the serialization process forces them
to populate. Also, when saving on the client side I always send back
a full graph of objects to the server. So any additions made to my
collections do show up on the server and get persisted. I admit that
deletes from a collection do not work using this approach. To get
deletes working, objects need to be marked for delete on the client
and then removed from the collection on the server after reattaching
to the session. But I think this is a common problem when working in
a detached state.
-Greg
On Dec 9, 5:29 am, noon <[EMAIL PROTECTED]> wrote:
> Just a precision : Hibernate4Gwt/Gilead *does not* lazy load any
> association from client side (it would lead to very poor
> performances !!!).
> It just take care of lazy but not loaded associations and persistent
> collections during serialization and deserialisation process.
>
> Another thing to know is that almost all of the above "quick"
> solutions does not work in all cases : just try to send a partially
> loaded entity on client side (=> Serialization Exception) or modify a
> collection in GWT code (exception or no effect on server-side)...
>
> Regards
> Bruno
>
> On 8 déc, 23:15, Greg <[EMAIL PROTECTED]> wrote:
>
>
>
> > I do the same exact trick, but I convert a PersistentBag to an
> > ArrayList.
>
> > The tricky part is figuring out where to put your "copy" code so that
> > it doesn't get in the way or complicate your existing code. I use a
> > custom field serializer, which is an undocumented feature of GWT.
>
> > If you have an object, say Foo, you can customize the GWT RPC
> > serialization for Foo by creating a class in the same package as Foo,
> > called Foo_CustomFieldSerializer. Then you add two static methods to
> > the class as follows:
>
> > public static void serialize(SerializationStreamWriter writer, Foo
> > instance) throws SerializationException {
>
> > }
>
> > public static void deserialize(SerializationStreamReader reader, Foo
> > instance) throws SerializationException {
>
> > }
>
> > Then for every field, you call the appropriate methods in the writer
> > or reader to serialize or deserialize. Here's the cool part. When
> > you encounter a collection managed by Hibernate, you can simply swap
> > out the collection for a GWT safe implementation. So if Foo has a one
> > to many collection called bars (say it's a List), you can safely
> > serialize it with the following code:
>
> > public static void serialize(SerializationStreamWriter writer, Foo
> > instance) throws SerializationException {
> > ...
> > writer.writeObject(new ArrayList(instance.getBars()));
> > ...
>
> > }
>
> > and the deserialization is just as easy
>
> > public static void deserialize(SerializationStreamReader reader, Foo
> > instance) throws SerializationException {
> > ...
> > instance.setBars((List)reader.readObject());
> > ...
>
> > }
>
> > The best part about using a custom field serializer is that your
> > original object does not get modified. I tried an approach where I
> > swapped out the collection just prior to returning from my RPC
> > method. This caused two problems. First it complicated the code.
> > Second, Hibernate detected a change to my object and persisted it.
> > This wasn't a huge problem, but it did cause an unnecessary write to
> > the database.
>
> > I also looked into Hibernate4GWT. But I found that if you don't need
> > to do lazy loading of persistent collections on the client side, then
> > Hibernate4GWT is overkill.
>
> > -Greg
>
> > On Dec 8, 2:55 pm, "Arthur Kalmenson" <[EMAIL PROTECTED]> wrote:
>
> > > It's also possible to force it to use a HashSet by copying the
> > > contents of the PersistentSet to a new HashSet. That worked for us.
>
> > > --
> > > Arthur Kalmenson
>
> > > On Sun, Dec 7, 2008 at 7:05 AM, gregor <[EMAIL PROTECTED]> wrote:
>
> > > > Hi,
>
> > > > PersistentSet is one of Hibernate's "magic collections". Like the
> > > > proxies that Hibernate also uses for lazy loading, domain objects so
> > > > adorned are incompatible with the GWT Emulation library and AFAIK
> > > > there is no direct way around it at the moment. You have to copy them
> > > > to DTO representations for transfer and copy them back on return.
>
> > > > Hibernate4gwt does this for you - have you had a look at it?
>
> > > > regards
> > > > gregor
>
> > > > On Dec 7, 9:54 am, LoneWolf <[EMAIL PROTECTED]> wrote:
> > > >> Hey,
> > > >> Our application is using Hibernate 3 as the persistence mechanism, and
> > > >> of course we have one-to-many relationship.
> > > >> The problem is when trying to pass a domain object that has a list of
> > > >> lazy initialized objects back to the browser, I got this exception:
> > > >> ++++
> > > >> Caused by: com.google.gwt.user.client.rpc.SerializationException: Type
> > > >> 'org.hibernate.collection.PersistentSet' was not included in the set
> > > >> of types which can be serialized by this SerializationPolicy or its
> > > >> Class object could not be loaded. For security purposes, this type
> > > >> will not be serialized.
> > > >> ++++
> > > >> Yes, I understand this exception but to overcome this issue?
> > > >> Thanks.- Hide quoted text -
>
> > > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
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