Hi,
I want to split up my seam application into 2 different application, so that I
can use one JBoss as a webserver and another one as the application-server with
the underlyng database. Therefor I use the EntityManager only on the
application-server, so that all the updates etc. on the database all go through
the same method. Now I experience problems when using my entities and want to
use object, that are lazy-loaded.
One example, I have a User-object with a UserLog:
| @Name("user")
| @Scope(ScopeType.SESSION)
| public class User implements Serializable {
| ...
|
| @OneToMany(cascade = CascadeType.ALL, mappedBy = "user",
fetch=FetchType.LAZY)
| private Set<UserLog> userLogCollection ;
|
| ...
|
| public Set<UserLog> getUserLogCollection() {
| return this.userLogCollection;
| }
|
| protected void setUserLogCollection(Set<UserLog> userLogCollection) {
| this.userLogCollection = userLogCollection;
| }
|
| public void addUserLog(UserLog userLog) {
| if (this.userLogCollection == null) {
| this.userLogCollection = new HashSet();
| }
| this.userLogCollection.add(userLog);
| }
|
|
When I Login I query the EnitityManager through my application-server and
return the user-object.
When I try to add a new UserLog-Object using the methods of my entity object I
get a LIE, probably because the user-object is detached:
| 16:45:59,978 ERROR [LazyInitializationException] failed to lazily
initialize a collection of role: common.entity.User.userLogCollection, no
session or session was closed
| org.hibernate.LazyInitializationException: failed to lazily initialize a
collection of role: common.entity.User.userLogCollection, no session or session
was closed
| at
org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)
| at
org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
| at
org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:343)
| at
org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
| at
org.hibernate.collection.PersistentSet.toString(PersistentSet.java:309)
| at java.lang.String.valueOf(String.java:2615)
| at java.lang.StringBuilder.append(StringBuilder.java:116)
|
When I do this through a method on my application-server together with a
em.merge, everything works fine, because the entity becomes managed again. But
this cannot be the solution, as would have to write a method for every
lazy-loaded object on my application-server.
| public User addUserLog(User user, UserLog userLog) {
| User userTmp = (User) em.merge(user);
| userTmp.addUserLog(userLog);
| return userTmp;
| }
|
I tryied to work with the Seam Managed Persistence Context, but as far as I
could see in the documentation I have to initialize the EntityManager through
the [EMAIL PROTECTED], which doesn´t seem very good, if I would like to have
seam-independent controller-beans on my application server.
What would be the best solution to work with lazily-loaded objects in a
distributed environment? Does anyone have some experiences with that and
therefor has a good recommendation?
Thank you very much
Thomas
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