java - Spring Data JPA save new Entity and get its all dependencies -

im saving entity database via spring data jpa save() method. method returns saved entity object, if im saving new entity, returned object isn't filled example @manytomany full entities.

as far know, when spring data jpa save new entity, uses entitymanager.persist() method, , if entity exist in database, save() method uses entitymanager.merge() method.

my question is, how save new entity in database , full dependencies in 1 transaction?

i trying add helper class, bean services extends, like:

public abstract class helperpersistenceservice<e extends abstractentity<i>, extends serializable> {      @persistencecontext     private entitymanager entitymanager;      @transactional     public e savewithmerge(e e) {         if (e.getid() == null) {             entitymanager.persist(e);         }         return entitymanager.merge(e);     }  } 

and works without @transactional method. got excepton:

javax.persistence.transactionrequiredexception: no entitymanager actual transaction available current thread - cannot reliably process 'persist' call     @ org.springframework.orm.jpa.sharedentitymanagercreator$sharedentitymanagerinvocationhandler.invoke(sharedentitymanagercreator.java:278)     @ com.sun.proxy.$proxy778.persist(unknown source) 

how solve problem?

have added cascade=persist,merge on many many relationship?

the behaviour you're after requires cascade present.