Hi,
Since this is an indirect recursion, i.e., from State -> Transition ->
State -> Transition -> ...
you need to add the recursionDepth in both State and Transition as shown below:
(1) State.java
@Entity
@FetchGroups( {
@FetchGroup(name = "State_OutgoingTransitions",
attributes = {...@fetchattribute(name = "outgoingTransitions",
recursionDepth = 10) }),
@FetchGroup(name = "State_IncomingTransitions",
attributes = {...@fetchattribute(name = "incomingTransitions",
recursionDepth = 10) }) })
public class State implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(length = 64)
private String name;
@OneToMany(mappedBy = "fromState",
cascade = {CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH})
private List<Transition> outgoingTransitions;
@OneToMany(mappedBy = "toState",
cascade = { CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH })
private List<Transition> incomingTransitions;
...
}
(2) Transition.java
@Entity
@FetchGroups( {
@FetchGroup(name = "Transition_ToState",
attributes = {...@fetchattribute(name = "toState", recursionDepth =
10) }),
@FetchGroup(name = "Transition_FromState",
attributes = {...@fetchattribute(name = "fromState", recursionDepth
= 10) }) })
public class Transition implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(length = 64)
private String name;
@ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH })
@JoinColumn(name = "FROM_STATE_ID", referencedColumnName = "ID")
private State fromState;
@ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH })
@JoinColumn(name = "TO_STATE_ID", referencedColumnName = "ID")
private State toState;
...
}
(3) When doing the findBy operation, add the fetch groups to the fetch plan:
EntityManager em = emf.createEntityManager();
OpenJPAEntityManager oem = OpenJPAPersistence.cast (em);
JDBCFetchPlan jfp = (JDBCFetchPlan)oem.getFetchPlan();
jfp.addFetchGroup("State_OutgoingTransitions");
jfp.addFetchGroup("State_IncomingTransitions");
jfp.addFetchGroup("Transition_ToState");
jfp.addFetchGroup("Transition_FromState");
State s1 = em.find(State.class, 2);
The resulting s1 should contain the complete graph.
Regards,
Fay
:
----- Original Message ----
From: Fay Wang <[email protected]>
To: [email protected]
Sent: Fri, October 23, 2009 2:44:13 PM
Subject: Re: Fetchgroups recursion problem
This apparently has something to do with the _availableRecursion in the
FetchConfigurationImpl. I hardcoded a big number and the whole thing is
retrieved. There seem a missing link between the recursionDepth in the
FetchGroup and this field. More investigation is underway...
Fay
----- Original Message ----
From: calin014 <[email protected]>
To: [email protected]
Sent: Fri, October 23, 2009 10:37:46 AM
Subject: Re: Fetchgroups recursion problem
Craig L Russell wrote:
>
> One other thing to consider: there is a fetch plan for each query that
> may be different from the fetch plan for other operations. If you're
> modifying the fetch plan after the query is created, the modifications
> won't affect the query.
>
Well, the order is:
OpenJPAEntityManager ojem = OpenJPAPersistence.cast(entityManager);
ojem.getFetchPlan().setMaxFetchDepth(15);
ojem.getFetchPlan().addFetchGroups("State_OutgoingTransitions",
"State_IncomingTransitions");
Flow flow = entityManager.find(Flow.class, id);
And the query is affected because, if i don't add the fetch groups, only the
first state gets loaded into memory.
Fay Wang wrote:
>
> By default, the max fetch depth is set to -1 for no limit. However, this
> graph is an "indirect recursion", i.e., from State -> Transition -> State.
> I think this makes Openjpa to stop prematurely...
>
If this is the case, is there a workaround?
--
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