xhtml:
<h:form>
<rich:dataTable value="#{action.contracts}" var="c">
 <h:column>
   <h:inputText value="#{c.name}" />
 </h:column>
</rich:dataTable>
 <h:commandButton action="#{action.save()}" value="save" />
</h:form>

Action.java
@Name("action")
@Scope(ScopeType.CONVERSATION)
public class Action {
  @In
  private EntityManager em;

  @DataModel 
  private List<contract> contracts;

  @Create
  @Begin
  public void create(){
    this.contracts = findAllConracts();
  }

  public void findAllContracts() {
    em.createQuery("from Contract ").getResultList();
  }

  @End
  public void save() {
    ;//I don't do anything here
  }
}

I edit the name and press save button, the new names were saved to the database. But I didn't do anything like "em.merge(..)", how can it save it?  Does seam save datamodel automatically ?