non-random ramble » hibernate http://jimbarritt.com/non-random adventures in code Fri, 23 Jul 2010 13:42:14 +0000 en hourly 1 http://wordpress.org/?v=3.0 Hibernate Proxy InstantiationException http://jimbarritt.com/non-random/2010/07/23/hibernate-proxy-instantiationexception/ http://jimbarritt.com/non-random/2010/07/23/hibernate-proxy-instantiationexception/#comments Fri, 23 Jul 2010 13:39:31 +0000 Jim Barritt http://jimbarritt.com/non-random/?p=602

Changing entities to be lazy loaded led me to the following problem:

@OneToMany(fetch = FetchType.LAZY)

Caused by: org.hibernate.HibernateException: Javassist Enhancement failed: Thing
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:142)
	at org.hibernate.proxy.pojo.javassist.JavassistProxyFactory.getProxy(JavassistProxyFactory.java:72)
	at org.hibernate.tuple.entity.AbstractEntityTuplizer.createProxy(AbstractEntityTuplizer.java:402)
	at org.hibernate.persister.entity.AbstractEntityPersister.createProxy(AbstractEntityPersister.java:3483)
….
Caused by: java.lang.InstantiationException: Thing_$$_javassist_38
	at java.lang.Class.newInstance0(Class.java:340)
	at java.lang.Class.newInstance(Class.java:308)
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:139)

Thanks to Kristian I jumped straight to the problem. From the Hibernate docs:

Cat has a no-argument constructor. All persistent classes must have a default constructor (which can be non-public) so that Hibernate can instantiate them using Constructor.newInstance(). It is recommended that you have a default constructor with at least package visibility for runtime proxy generation in Hibernate.

This should probably read “It is essential….”

Anyway now everything is real lazy so happy days.

]]> http://jimbarritt.com/non-random/2010/07/23/hibernate-proxy-instantiationexception/feed/ 0 Log4J settings for working with Hibernate http://jimbarritt.com/non-random/2010/07/23/log4j-settings-for-working-with-hibernate/ http://jimbarritt.com/non-random/2010/07/23/log4j-settings-for-working-with-hibernate/#comments Fri, 23 Jul 2010 12:28:37 +0000 Jim Barritt http://jimbarritt.com/non-random/?p=588

]]> http://jimbarritt.com/non-random/2010/07/23/log4j-settings-for-working-with-hibernate/feed/ 0 Hibernate components and relationships http://jimbarritt.com/non-random/2008/09/29/hibernat-components-and-relationships/ http://jimbarritt.com/non-random/2008/09/29/hibernat-components-and-relationships/#comments Mon, 29 Sep 2008 15:16:32 +0000 Jim Barritt http://jimbarritt.com/non-random/2008/09/29/hibernat-components-and-relationships/ Situation: you have a hibernate component which itself has a link to another object (e.g. many-to-one)

When loading, if hibernate is not able to satisfy the dependency, it will NOT set the field for your component.

e.g. we have :
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