Hello,
Thank you for your response. It worked. However, it works just when loading
the graph from the first state. If i try to load the flow directly it
doesn't work.
This is what i did:
@Entity
@FetchGroups( {
@FetchGroup(name = "State_outgoingTransitions", attributes = {
@FetchAttribute(name = "outgoingTransitions", recursionDepth = -1) }),
@FetchGroup(name = "State_incomingTransitions", attributes = {
@FetchAttribute(name = "incomingTransitions", recursionDepth = -1) }) })
public class State implements Serializable {
...
@Entity
@FetchGroups( {
@FetchGroup(name = "State_outgoingTransitions", attributes = {
@FetchAttribute(name = "fromState", recursionDepth = -1) }),
@FetchGroup(name = "State_incomingTransitions", attributes = {
@FetchAttribute(name = "toState", recursionDepth = -1) }) })
public class Transition implements Serializable {
...
...
System.out.println("FLOW: LAZY LOADING: ");
EntityManager em = emf.createEntityManager();
Flow f = em.find(Flow.class, 2L);
System.out.println(f);
em.close();
System.out.println("FLOW: FETCH GROUPS: ");
em = emf.createEntityManager();
OpenJPAEntityManager oem = OpenJPAPersistence.cast(em);
oem.getFetchPlan().addFetchGroups("State_outgoingTransitions",
"State_incomingTransitions");
f = em.find(Flow.class, 2L);
//close persistence context
em.close();
System.out.println(f);
System.out.println("STATE: FETCH GROUPS");
em = emf.createEntityManager();
oem = OpenJPAPersistence.cast(em);
oem.getFetchPlan().addFetchGroups("State_outgoingTransitions",
"State_incomingTransitions");
State s = em.find(State.class, 4L);
//close persistence context
em.close();
//build the flow object
f = new Flow();
f.setInitialState(s);
System.out.println(f);
...
And this is the output:
FLOW: LAZY LOADING:
[s1, s2, s4, s5, s3]
[t12, t24, t45, t23, t34, t31, t32, t21]
FLOW: FETCH GROUPS:
[s1, s2, s3]
[t12, t24, t23, t34, t31, t32, t21]
STATE: FETCH GROUPS
[s1, s2, s4, s5, s3]
[t12, t24, t45, t23, t34, t31, t32, t21]
As you can see, when trying to load the flow directly with f =
em.find(Flow.class, 2L) the result is the same as before.
Anyway, i think i can handle it from here. Thanks a lot for your help.
Fay Wang wrote:
>
> 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
>
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