JPA best practices?

java jpa entity pojo
Hay picture Hay · Aug 17, 2011 · Viewed 8k times · Source

I’m working on a little multi-tier application utilizing JPA/EclipseLink as a persistence layer. In my current design I have two sets of objects, POJOs and Entity objects, I use POJOs for general programming tasks and Entity classes are used for DB read/write and table mapping.

Now is it necessary to have POJO=>Entity mapping (problematically) and then a second Entity==>DB tables mapping (JPA annotations)? I find it easier to just use Entity classes as my main java objects and persist them whenever necessary, after all Entity classes are essentially POJO with with couple of JPA annotations.

Also in a situation where it's indeed necessary to keep things separated, what is the best place to do the POJO=>Entity mapping, currently I do this in a CRUD method, e.g.

public void addCustomerPOJO(Customer customerPOJO){
   //Cteat EntityManager and start a Transaction

   //Create Entity class and populate it with values 
   //from the passed-in regular (non entity) Customer class

  //Persiste and close
}

Is there a better or more common way to do this?

Answer

Jeremy picture Jeremy · Aug 17, 2011

There is nothing wrong with using your entities as your domain objects. You have to be aware of using entities that have been detached and whatnot, but that can be managed.

I would not artificially create work for yourself by forcing each entity to be mapped to another bean (or POJO). Sometimes it is necessary to wrap many entities (or values from entities) into a bean, but only do it if there is a good reason.

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