Seams EntityManager...

[nimo22]

I have the following Scenario:

SessionBean A, EntityBean B, ManagedBean C (POJO for my view).

ONLY in A, I have injected Seams EntityManager:

public class A implements aLocal {

@In
EntityManager entityManager;
..
}

In my View-Bean C, I inject the Interface aLocal and a Instance of B:

public class C {

//retrieves methods from aLocal
@In
aLocal alocal;

@In(required=true) @Out (required = false)
private B b;

  @Begin
  public void changeB {
   b.setAttribute("hello");

    }
..}

all works perfectyl, BUT:

My Seam-managed EntityManager does automatically make a database-operation when I do something like

b.setName("hello");

even when I do NOT have explicitly inject a EntityManager in my ManagedBean C or call the method

entityManager.merge(b)

As I have no entityManager in C available, I cannot do something like:

if (entityManager.isOpen())
 { //detach the Entity-Instance} }

I absolutely want avoid, to inject a EntityManager into a web component (in my case the managedBean C).

Another point is, when I do in my EntityBean B something like:

@Entity
public class B implements Serializable{

private String name;

public String getName() {
        return name.trim();
    }

and call anywhere this getter, then the database-operation UPDATE NAME FROM B is made. Why?

I do not have call the merge/persist-Method nor I have no entityManager-Instance (in my view-bean).

Have it to do with call by value and call by reference or with Seams (implicitly extended) EntityManager?? Have it to do with my packaging? I have used SEAM-Gen to generate my EJB-Project.

I want that my WARs are managed by the servlet-container (having no direct access to the EJBs entityManager, and my EARs (sessionBeans, entityBeans) should be managed by the EJB-Container (having access to the entityManager).

I need the instance from a entity-Bean and change the values only when I do explicitly want it (with methods such as persist, merge,..).

Any Ideas?

[wilczarz.wilczarz.gmail.com]

Use

@Begin( flushMode = FlushModeType.MANUAL )

No method within the conversation will write the database until you explicitly call entityManager.flush()

[nimo22]

Thanks but this is not the intention what I want to show:

I have no entityManager-Instance in my View-Bean C and want not to provide a instance as I want to decouple the view from the session-bean.

I cannot call entityManager.flush() in my View Bean C, as I do not want to provide a EntityManager-Instance in my ManagedBean C.

I absolutely want to avoid injecting a EntityManager into a web component (in my case the managedBean C).

I guess, this is the problem:

//retrieves methods from aLocal
@In
aLocal alocal;

Should I use this instead?:

//retrieves methods from aLocal
@EJB
aLocal alocal;

[swd847]

Your problem is that by default the seam managed persistence context will flush itself to the database automatically, unless you either start a conversation with a flush mode of MANUAL or set the flush mode yourself. There is not need to inject an EntityManager to make this change, you can do it through pages.xml (<begin-conversation flush-mode="MANUAL"/>)

[nimo22]

Thank you, I have done that.