I want to eagerly fetch a many-to-one association (Cat->Owner). The documentation (HiA, p.147) says "... So, if we want to reenable eager fetching for the association, now proxying is enabled, we would specify <many-to-one name="item" class="Item" outer-join="true"> ..."

Still if I execute the code, closing the session before reading the name property on the associated owner, an lazy initialization exception is thrown.

Hibernate version: 2.1.7

Mapping documents:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class name="test.Cat" table="CAT">
<id name="id">
<generator class="increment"/>
</id>
<property name="name"/>
<many-to-one name="owner" column="owner_id" outer-join="true"/>
</class>
<class name="test.Owner" proxy="test.Owner" table="OWNER">
<id name="id">
<generator class="increment"/>
</id>
<property name="name"/>
<set name="cats" lazy="false" inverse="true" cascade="save-update">
<key column="owner_id"/>
<one-to-many class="test.Cat"/>
</set>
</class>
</hibernate-mapping>

Code (between sessionFactory.openSession() and session.close()):

Session session = getSession();
List cats = session.find("from Cat");
List owners = session.find("from Owner");
session.close();
System.out.println("cats: ");
for (Iterator iter = cats.iterator(); iter.hasNext();) {
System.out.println(iter.next()); //includes owner.name
}
System.out.println("owners: ");
for (Iterator iter = owners.iterator(); iter.hasNext();) {
System.out.println(iter.next());
}

Full stack trace of any exception that occurs:

net.sf.hibernate.LazyInitializationException: Exception initializing proxy: [test.Owner#1]
at net.sf.hibernate.proxy.LazyInitializer.initializeWrapExceptions(LazyInitializer.java:64)
at net.sf.hibernate.proxy.LazyInitializer.getImplementation(LazyInitializer.java:164)
at net.sf.hibernate.proxy.CGLIBLazyInitializer.intercept(CGLIBLazyInitializer.java:108)
at test.Owner$$EnhancerByCGLIB$$ba744227.getName(<generated>)
at test.Cat.toString(Cat.java:28)
at java.lang.String.valueOf(Unknown Source)
at java.io.PrintStream.print(Unknown Source)
at java.io.PrintStream.println(Unknown Source)
at Shower.main(Shower.java:27)
Caused by: net.sf.hibernate.HibernateException: Could not initialize proxy - the owning Session was closed
at net.sf.hibernate.proxy.LazyInitializer.initialize(LazyInitializer.java:47)
at net.sf.hibernate.proxy.LazyInitializer.initializeWrapExceptions(LazyInitializer.java:60)
... 8 more

Name and version of the database you are using: hsqldb 1.7.2.2

Debug level Hibernate log excerpt:

15:46:16,498=> INFO Environment - Hibernate 2.1.7
15:46:16,498=> INFO Environment - hibernate.properties not found
15:46:16,508=> INFO Environment - using CGLIB reflection optimizer
15:46:16,508=> INFO Environment - using JDK 1.4 java.sql.Timestamp handling
15:46:16,508=> INFO Configuration - Mapping file: mappings.xml
15:46:16,548=>DEBUG DTDEntityResolver - trying to locate http://hibernate.sourceforge.net/hibern ... ng-2.0.dtd in classpath under net/sf/hibernate/
15:46:16,558=>DEBUG DTDEntityResolver - found http://hibernate.sourceforge.net/hibern ... ng-2.0.dtd in classpath
15:46:16,668=> INFO Binder - Mapping class: test.Cat -> CAT
15:46:16,708=>DEBUG Binder - Mapped property: id -> id, type: long
15:46:16,718=>DEBUG Binder - Mapped property: name -> name, type: string
15:46:16,718=>DEBUG Binder - Mapped property: owner -> owner_id, type: test.Owner
15:46:16,718=> INFO Binder - Mapping class: test.Owner -> OWNER
15:46:16,718=>DEBUG Binder - Mapped property: id -> id, type: long
15:46:16,718=>DEBUG Binder - Mapped property: name -> name, type: string
15:46:16,728=>DEBUG Binder - Mapped property: cats, type: java.util.Set
15:46:16,728=> INFO Configuration - processing one-to-many association mappings
15:46:16,728=>DEBUG Binder - Second pass for collection: test.Owner.cats
15:46:16,728=> INFO Binder - Mapping collection: test.Owner.cats -> CAT
15:46:16,728=>DEBUG Binder - Mapped collection key: owner_id, one-to-many: test.Cat
15:46:16,728=> INFO Configuration - processing one-to-one association property references
15:46:16,728=> INFO Configuration - processing foreign key constraints
15:46:16,738=>DEBUG Configuration - resolving reference to class: test.Owner
15:46:16,748=> INFO Dialect - Using dialect: net.sf.hibernate.dialect.HSQLDialect
15:46:16,758=>DEBUG SQLExceptionConverterFactory - Using dialect defined converter
15:46:16,758=> INFO SettingsFactory - Use outer join fetching: true
15:46:16,758=> INFO DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!)
15:46:16,758=> INFO DriverManagerConnectionProvider - Hibernate connection pool size: 20
15:46:16,768=> INFO DriverManagerConnectionProvider - using driver: org.hsqldb.jdbcDriver at URL: jdbc:hsqldb:hsql://localhost:9001/
15:46:16,768=> INFO DriverManagerConnectionProvider - connection properties: {user=sa, password=}
15:46:16,768=> INFO TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended)
15:46:16,768=>DEBUG DriverManagerConnectionProvider - total checked-out connections: 0
15:46:16,768=>DEBUG DriverManagerConnectionProvider - opening new JDBC connection
15:46:16,839=>DEBUG DriverManagerConnectionProvider - created connection to: jdbc:hsqldb:hsql://localhost:9001/, Isolation Level: 1
15:46:16,849=>DEBUG DriverManagerConnectionProvider - returning connection to pool, pool size: 1
15:46:16,849=> INFO SettingsFactory - Use scrollable result sets: true
15:46:16,849=> INFO SettingsFactory - Use JDBC3 getGeneratedKeys(): false
15:46:16,849=> INFO SettingsFactory - Optimize cache for minimal puts: false
15:46:16,849=> INFO SettingsFactory - Query language substitutions: {}
15:46:16,849=> INFO SettingsFactory - cache provider: net.sf.hibernate.cache.EhCacheProvider
15:46:16,849=> INFO Configuration - instantiating and configuring caches
15:46:16,939=> INFO SessionFactoryImpl - building session factory
15:46:16,939=>DEBUG SessionFactoryImpl - instantiating session factory with properties: {hibernate.connection.password=, hibernate.dialect=net.sf.hibernate.dialect.HSQLDialect, hibernate.connection.user=sa, hibernate.connection.url=jdbc:hsqldb:hsql://localhost:9001/, hibernate.connection.driver_class=org.hsqldb.jdbcDriver}
15:46:17,029=> INFO ReflectHelper - reflection optimizer disabled for: test.Cat, BulkBeanException: Property is private (property setName)
15:46:17,039=> INFO ReflectHelper - reflection optimizer disabled for: test.Owner, BulkBeanException: Property is private (property setName)
15:46:17,249=>DEBUG SessionFactoryObjectFactory - initializing class SessionFactoryObjectFactory
15:46:17,249=>DEBUG SessionFactoryObjectFactory - registered: 402882c001af7ca60101af7ca7a10000 (unnamed)
15:46:17,249=> INFO SessionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured
15:46:17,249=>DEBUG SessionFactoryImpl - instantiated session factory
15:46:17,289=>DEBUG SessionImpl - opened session
15:46:17,289=>DEBUG SessionImpl - find: from Cat
15:46:17,299=>DEBUG QueryTranslator - compiling query
15:46:17,309=>DEBUG SessionImpl - flushing session
15:46:17,309=>DEBUG SessionImpl - Flushing entities and processing referenced collections
15:46:17,309=>DEBUG SessionImpl - Processing unreferenced collections
15:46:17,309=>DEBUG SessionImpl - Scheduling collection removes/(re)creates/updates
15:46:17,309=>DEBUG SessionImpl - Flushed: 0 insertions, 0 updates, 0 deletions to 0 objects
15:46:17,309=>DEBUG SessionImpl - Flushed: 0 (re)creations, 0 updates, 0 removals to 0 collections
15:46:17,309=>DEBUG SessionImpl - Dont need to execute flush
15:46:17,309=>DEBUG QueryTranslator - HQL: from test.Cat
15:46:17,309=>DEBUG QueryTranslator - SQL: select cat0_.id as id, cat0_.name as name, cat0_.owner_id as owner_id from CAT cat0_
15:46:17,309=>DEBUG BatcherImpl - about to open: 0 open PreparedStatements, 0 open ResultSets
15:46:17,309=>DEBUG DriverManagerConnectionProvider - total checked-out connections: 0
15:46:17,309=>DEBUG DriverManagerConnectionProvider - using pooled JDBC connection, pool size: 0
15:46:17,309=>DEBUG SQL - select cat0_.id as id, cat0_.name as name, cat0_.owner_id as owner_id from CAT cat0_
15:46:17,309=>DEBUG BatcherImpl - preparing statement
15:46:17,329=>DEBUG Loader - processing result set
15:46:17,359=>DEBUG LongType - returning '1' as column: id
15:46:17,359=>DEBUG Loader - result row: 1
15:46:17,359=>DEBUG Loader - Initializing object from ResultSet: 1
15:46:17,359=>DEBUG Loader - Hydrating entity: test.Cat#1
15:46:17,359=>DEBUG StringType - returning 'klaartje' as column: name
15:46:17,359=>DEBUG LongType - returning '1' as column: owner_id
15:46:17,359=>DEBUG LongType - returning '2' as column: id
15:46:17,359=>DEBUG Loader - result row: 2
15:46:17,359=>DEBUG Loader - Initializing object from ResultSet: 2
15:46:17,359=>DEBUG Loader - Hydrating entity: test.Cat#2
15:46:17,359=>DEBUG StringType - returning 'pietje' as column: name
15:46:17,359=>DEBUG LongType - returning '1' as column: owner_id
15:46:17,359=>DEBUG LongType - returning '3' as column: id
15:46:17,359=>DEBUG Loader - result row: 3
15:46:17,359=>DEBUG Loader - Initializing object from ResultSet: 3
15:46:17,359=>DEBUG Loader - Hydrating entity: test.Cat#3
15:46:17,359=>DEBUG StringType - returning 'kees' as column: name
15:46:17,359=>DEBUG LongType - returning '2' as column: owner_id
15:46:17,359=>DEBUG Loader - done processing result set (3 rows)
15:46:17,359=>DEBUG BatcherImpl - done closing: 0 open PreparedStatements, 0 open ResultSets
15:46:17,359=>DEBUG BatcherImpl - closing statement
15:46:17,359=>DEBUG Loader - total objects hydrated: 3
15:46:17,359=>DEBUG SessionImpl - resolving associations for [test.Cat#1]
15:46:17,359=>DEBUG SessionImpl - loading [test.Owner#1]
15:46:17,369=>DEBUG SessionImpl - done materializing entity [test.Cat#1]
15:46:17,369=>DEBUG SessionImpl - resolving associations for [test.Cat#2]
15:46:17,369=>DEBUG SessionImpl - loading [test.Owner#1]
15:46:17,369=>DEBUG SessionImpl - done materializing entity [test.Cat#2]
15:46:17,369=>DEBUG SessionImpl - resolving associations for [test.Cat#3]
15:46:17,369=>DEBUG SessionImpl - loading [test.Owner#2]
15:46:17,369=>DEBUG SessionImpl - done materializing entity [test.Cat#3]
15:46:17,369=>DEBUG SessionImpl - initializing non-lazy collections
15:46:17,369=>DEBUG SessionImpl - find: from Owner
15:46:17,369=>DEBUG QueryTranslator - compiling query
15:46:17,369=>DEBUG SessionImpl - flushing session
15:46:17,369=>DEBUG SessionImpl - Flushing entities and processing referenced collections
15:46:17,369=>DEBUG SessionImpl - Processing unreferenced collections
15:46:17,369=>DEBUG SessionImpl - Scheduling collection removes/(re)creates/updates
15:46:17,369=>DEBUG SessionImpl - Flushed: 0 insertions, 0 updates, 0 deletions to 3 objects
15:46:17,369=>DEBUG SessionImpl - Flushed: 0 (re)creations, 0 updates, 0 removals to 0 collections
15:46:17,369=>DEBUG Printer - listing entities:
15:46:17,369=>DEBUG Printer - test.Cat{owner=Owner#2, name=kees, id=3}
15:46:17,369=>DEBUG Printer - test.Cat{owner=Owner#1, name=klaartje, id=1}
15:46:17,369=>DEBUG Printer - test.Cat{owner=Owner#1, name=pietje, id=2}
15:46:17,369=>DEBUG SessionImpl - Dont need to execute flush
15:46:17,369=>DEBUG QueryTranslator - HQL: from test.Owner
15:46:17,369=>DEBUG QueryTranslator - SQL: select owner0_.id as id, owner0_.name as name from OWNER owner0_
15:46:17,369=>DEBUG BatcherImpl - about to open: 0 open PreparedStatements, 0 open ResultSets
15:46:17,369=>DEBUG SQL - select owner0_.id as id, owner0_.name as name from OWNER owner0_
15:46:17,369=>DEBUG BatcherImpl - preparing statement
15:46:17,369=>DEBUG Loader - processing result set
15:46:17,369=>DEBUG LongType - returning '1' as column: id
15:46:17,369=>DEBUG Loader - result row: 1
15:46:17,369=>DEBUG Loader - Initializing object from ResultSet: 1
15:46:17,369=>DEBUG Loader - Hydrating entity: test.Owner#1
15:46:17,369=>DEBUG StringType - returning 'Karel' as column: name
15:46:17,369=>DEBUG LongType - returning '2' as column: id
15:46:17,369=>DEBUG Loader - result row: 2
15:46:17,369=>DEBUG Loader - Initializing object from ResultSet: 2
15:46:17,369=>DEBUG Loader - Hydrating entity: test.Owner#2
15:46:17,369=>DEBUG StringType - returning 'Maaike' as column: name
15:46:17,369=>DEBUG Loader - done processing result set (2 rows)
15:46:17,369=>DEBUG BatcherImpl - done closing: 0 open PreparedStatements, 0 open ResultSets
15:46:17,369=>DEBUG BatcherImpl - closing statement
15:46:17,369=>DEBUG Loader - total objects hydrated: 2
15:46:17,369=>DEBUG SessionImpl - resolving associations for [test.Owner#1]
15:46:17,369=>DEBUG SessionImpl - creating collection wrapper:[test.Owner.cats#1]
15:46:17,369=>DEBUG SessionImpl - done materializing entity [test.Owner#1]
15:46:17,369=>DEBUG SessionImpl - resolving associations for [test.Owner#2]
15:46:17,369=>DEBUG SessionImpl - creating collection wrapper:[test.Owner.cats#2]
15:46:17,369=>DEBUG SessionImpl - done materializing entity [test.Owner#2]
15:46:17,369=>DEBUG SessionImpl - initializing non-lazy collections
15:46:17,369=>DEBUG SessionImpl - initializing collection [test.Owner.cats#2]
15:46:17,369=>DEBUG SessionImpl - checking second-level cache
15:46:17,369=>DEBUG SessionImpl - collection not cached
15:46:17,369=>DEBUG BatcherImpl - about to open: 0 open PreparedStatements, 0 open ResultSets
15:46:17,369=>DEBUG SQL - select cats0_.owner_id as owner_id__, cats0_.id as id__, cats0_.id as id0_, cats0_.name as name0_, cats0_.owner_id as owner_id0_ from CAT cats0_ where cats0_.owner_id=?
15:46:17,369=>DEBUG BatcherImpl - preparing statement
15:46:17,379=>DEBUG LongType - binding '2' to parameter: 1
15:46:17,379=>DEBUG Loader - result set contains (possibly empty) collection: [test.Owner.cats#2]
15:46:17,379=>DEBUG SessionImpl - uninitialized collection: initializing
15:46:17,379=>DEBUG Loader - processing result set
15:46:17,379=>DEBUG LongType - returning '3' as column: id0_
15:46:17,379=>DEBUG Loader - result row: 3
15:46:17,379=>DEBUG LongType - returning '2' as column: owner_id__
15:46:17,379=>DEBUG Loader - found row of collection: [test.Owner.cats#2]
15:46:17,379=>DEBUG SessionImpl - reading row
15:46:17,379=>DEBUG LongType - returning '3' as column: id__
15:46:17,379=>DEBUG SessionImpl - loading [test.Cat#3]
15:46:17,379=>DEBUG SessionImpl - attempting to resolve [test.Cat#3]
15:46:17,379=>DEBUG SessionImpl - resolved object in session cache [test.Cat#3]
15:46:17,379=>DEBUG Loader - done processing result set (1 rows)
15:46:17,379=>DEBUG BatcherImpl - done closing: 0 open PreparedStatements, 0 open ResultSets
15:46:17,379=>DEBUG BatcherImpl - closing statement
15:46:17,379=>DEBUG Loader - total objects hydrated: 0
15:46:17,379=>DEBUG SessionImpl - 1 collections were found in result set
15:46:17,379=>DEBUG SessionImpl - collection fully initialized: [test.Owner.cats#2]
15:46:17,379=>DEBUG SessionImpl - 1 collections initialized
15:46:17,379=>DEBUG SessionImpl - collection initialized
15:46:17,379=>DEBUG SessionImpl - initializing collection [test.Owner.cats#1]
15:46:17,379=>DEBUG SessionImpl - checking second-level cache
15:46:17,379=>DEBUG SessionImpl - collection not cached
15:46:17,379=>DEBUG BatcherImpl - about to open: 0 open PreparedStatements, 0 open ResultSets
15:46:17,379=>DEBUG SQL - select cats0_.owner_id as owner_id__, cats0_.id as id__, cats0_.id as id0_, cats0_.name as name0_, cats0_.owner_id as owner_id0_ from CAT cats0_ where cats0_.owner_id=?
15:46:17,379=>DEBUG BatcherImpl - preparing statement
15:46:17,389=>DEBUG LongType - binding '1' to parameter: 1
15:46:17,389=>DEBUG Loader - result set contains (possibly empty) collection: [test.Owner.cats#1]
15:46:17,389=>DEBUG SessionImpl - uninitialized collection: initializing
15:46:17,389=>DEBUG Loader - processing result set
15:46:17,389=>DEBUG LongType - returning '1' as column: id0_
15:46:17,389=>DEBUG Loader - result row: 1
15:46:17,389=>DEBUG LongType - returning '1' as column: owner_id__
15:46:17,389=>DEBUG Loader - found row of collection: [test.Owner.cats#1]
15:46:17,389=>DEBUG SessionImpl - reading row
15:46:17,389=>DEBUG LongType - returning '1' as column: id__
15:46:17,389=>DEBUG SessionImpl - loading [test.Cat#1]
15:46:17,389=>DEBUG SessionImpl - attempting to resolve [test.Cat#1]
15:46:17,389=>DEBUG SessionImpl - resolved object in session cache [test.Cat#1]
15:46:17,389=>DEBUG LongType - returning '2' as column: id0_
15:46:17,389=>DEBUG Loader - result row: 2
15:46:17,389=>DEBUG LongType - returning '1' as column: owner_id__
15:46:17,389=>DEBUG Loader - found row of collection: [test.Owner.cats#1]
15:46:17,389=>DEBUG SessionImpl - reading row
15:46:17,389=>DEBUG LongType - returning '2' as column: id__
15:46:17,389=>DEBUG SessionImpl - loading [test.Cat#2]
15:46:17,389=>DEBUG SessionImpl - attempting to resolve [test.Cat#2]
15:46:17,389=>DEBUG SessionImpl - resolved object in session cache [test.Cat#2]
15:46:17,389=>DEBUG Loader - done processing result set (2 rows)
15:46:17,389=>DEBUG BatcherImpl - done closing: 0 open PreparedStatements, 0 open ResultSets
15:46:17,389=>DEBUG BatcherImpl - closing statement
15:46:17,389=>DEBUG Loader - total objects hydrated: 0
15:46:17,389=>DEBUG SessionImpl - 1 collections were found in result set
15:46:17,389=>DEBUG SessionImpl - collection fully initialized: [test.Owner.cats#1]
15:46:17,389=>DEBUG SessionImpl - 1 collections initialized
15:46:17,389=>DEBUG SessionImpl - collection initialized
15:46:17,389=>DEBUG SessionImpl - closing session
15:46:17,389=>DEBUG SessionImpl - disconnecting session
15:46:17,389=>DEBUG DriverManagerConnectionProvider - returning connection to pool, pool size: 1
15:46:17,389=>DEBUG SessionImpl - transaction completion

hi,
what about using FETCH in your HQL?

I could use FETCH in HQL, but why doesn't the mapping property work?
This is a small example, we are currently working on a large project with a few hundered mapped classes and relations. Mostly we fetch objects by id, without writing the HQL. We would have to switch to HQL for all those queries and fetch the proxies. If we could use the mapping to fetch it eagerly on ceratin relations, this would be an ENORMOUS advantage.

It works in our tests and everywhere else, so its somewhere in your code. Maybe you are using the wrong set of mapping files or something.

Could you point me to a test where it works? I have the code on my computer.
What part of the Hibernate should take care of the initialization of associated proxies? I could set a break point and see if the code get;s there.

Hibernate comes with hundreds of unit tests.

That is exactly why I ask for a pointer, since most of them won't touch the problem I'm talking about.

I'm in a good mood today, so here you go:


Paste this into CaveatEmptor as a new test, go into Item.hbm.xml, set outer-join="true" for the seller, go into hibernate.cfg.xml, enable show_sql, run the test and watch your console.

Thanks very much for the example!
Unfortunately I cannot find this class CaveatEmptor. I have the source of 2.1.7c...

oke, I see, the HiA example. Have to download that, thanks for replies.