Spring @Transactional placement -

i'm playing little spring/jpa2 understand better how works. during experiments found strange behaviour. question is:

why following code works (confirmed record added in db):

@repository public class userdao {      @persistencecontext     entitymanager em;      @transactional     public void add(user user) {         doadd(user);     }      public void doadd(user user) {         em.persist(user);     } } 

but following (@transactional annotation moved inner method):

@repository public class userdao {      @persistencecontext     entitymanager em;      public void add(user user) {         doadd(user);     }      @transactional     public void doadd(user user) {         em.persist(user);     } } 

throws exception:

javax.persistence.transactionrequiredexception: no transactional entitymanager available     @ org.springframework.orm.jpa.sharedentitymanagercreator$sharedentitymanagerinvocationhandler.invoke(sharedentitymanagercreator.java:273)     @ com.sun.proxy.$proxy556.persist(unknown source)     @ com.example.userdao.doadd(userdao.java:24)     ... 

in proxy mode (which default), external method calls coming in through proxy intercepted. means self-invocation, in effect, method within target object calling method of target object, not lead actual transaction @ runtime if invoked method marked @transactional.

source

the @transactional annotation support works wrapping actual dao instance in proxy, intercepts method calls , starts/commits transaction. in second example actual userdao instance calling dosave method , therefore there no proxy intercept method call.