[jboss-user] [EJB 3.0] - Re: Extended Persistence Context and merge()

radl01 do-not-reply at jboss.com
Wed May 16 16:47:35 EDT 2007

As you sead merge is used for detached objects and persist for atached ones. 
Short example for persist (update action)

   EntityManger em;

  Tab02000 recentRecord = (Tab02000)em.find(Tab02000.class, key);
  .. do some changes to recentRecord
  em.persist(recentRecord);  // in this case JPA will call update action because you are changing existing object

Short example for merge

   EntityManger em;
   Tab02000 newRecord = new Tab02000();
    ... set all values

The second example is BAD PRACTISE of using JPA


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