Hello,
I have a strange behavior during selection of my Nodes from database. I have a
graph structure and I want to delete all child Nodes that are connected to me
(the root Node) with a "cascaded=true" property on my Edge object.
I have the following entities (source code):
@Entity
@Table(name = "NODE")
public class Node implements ICopyable {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator="NodeSeq")
@SequenceGenerator(name="NodeSeq",sequenceName="NODE_ID_SEQ",
allocationSize=50)
@Column(name = "ID")
private long id;
@Version
@Column(name = "VERSION")
private int version;
@OneToMany(mappedBy = "to", fetch = FetchType.LAZY, cascade =
CascadeType.ALL, orphanRemoval = true)
private Set<Edge> inputs = new HashSet<Edge>();
@OneToMany(mappedBy = "from", fetch = FetchType.LAZY, cascade =
CascadeType.ALL, orphanRemoval = true)
private Set<Edge> outputs = new HashSet<Edge>();
}
@Entity
@Table(name = "EDGE")
public class Edge {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "EdgeSeq")
@SequenceGenerator(name = "EdgeSeq", sequenceName = "EDGE_ID_SEQ",
allocationSize = 50)
@Column(name = "ID")
private long id;
@Version
@Column(name = "VERSION")
private int version;
@Basic(fetch = FetchType.LAZY)
@Column(name = "CASCADED", updatable = false)
private boolean cascaded;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "FROM_ID", nullable = false, updatable = false)
private Node from;
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
@JoinColumn(name = "TO_ID", nullable = false, updatable = false)
private Node to;
}
The code I execute to select all child Nodes is:
private static final String QUERY_OUTPUTS = "SELECT n FROM Edge e JOIN e.to
AS n WHERE e.from = :theNode AND e.cascaded = " + true;
private Set<Node> fetchOutputs(Node current, Set<Node> previous) {
if (previous.contains(current)) {
// Already fetched
return previous;
}
previous.add(current);
Query query = getEntityManager().createQuery(QUERY_OUTPUTS);
query.setParameter("theNode", current);
List<?> outputs = query.getResultList();
for (Object output : outputs) {
// ClassCastException here but only the second time it is called?!
fetchOutputs((Node) output, previous);
}
return previous;
}
The strange thing is that I get a ClassCastException in the fetchOutputs method
(in loop) but only the second time I get there (recursive method).
First select my root Node:
[2009-04-19 10:53:45,937] DEBUG org.jenmo.core.repository.DefaultDeleteAction
SELECT n FROM Node n WHERE n.id = :theId
3558 JenmoPU TRACE [main] openjpa.jdbc.SQL - <t 236054577, conn 966979630>
executing prepstmnt 254232091 SELECT t0.ID, t0.VERSION, t0.NODETYPE_ID FROM
NODE t0 WHERE (t0.ID = ?) [params=(long) 50]
3559 JenmoPU INFO [main] openjpa.Runtime - Query "SELECT n FROM Node n
WHERE n.id = :theId" is excluded temporarily due to "Excluded by user".
Then select "child" Nodes (fetchOutputs method):
[2009-04-19 10:53:45,944] DEBUG org.jenmo.core.repository.DefaultDeleteAction
SELECT n FROM Edge e JOIN e.to AS n WHERE e.from = :theNode AND e.cascaded =
true
3576 JenmoPU TRACE [main] openjpa.jdbc.SQL - <t 236054577, conn 966979630>
executing prepstmnt 1742602365 SELECT t1.ID, t1.VERSION, t1.NODETYPE_ID FROM
EDGE t0 INNER JOIN NODE t1 ON t0.TO_ID = t1.ID WHERE (t0.FROM_ID = ? AND
t0.CASCADED = ?) [params=(long) 50, (boolean) true]
[2009-04-19 10:53:45,976] DEBUG org.jenmo.core.repository.DefaultDeleteAction
SELECT n FROM Edge e JOIN e.to AS n WHERE e.from = :theNode AND e.cascaded =
true
3596 JenmoPU TRACE [main] openjpa.jdbc.SQL - <t 236054577, conn 966979630>
executing prepstmnt 631900693 SELECT t1.ID, t1.VERSION, t1.NODETYPE_ID FROM
EDGE t0 INNER JOIN NODE t1 ON t0.TO_ID = t1.ID WHERE (t0.FROM_ID = ? AND
t0.CASCADED = ?) [params=(long) 100, (boolean) true]
And the exception:
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to
org.jenmo.core.domain.Node
at
org.jenmo.core.repository.del.NodeDeleteAction.fetchOutputs(NodeDeleteAction.java:87)
at
org.jenmo.core.repository.del.NodeDeleteAction.fetchOutputs(NodeDeleteAction.java:87)
at
org.jenmo.core.repository.del.NodeDeleteAction.delete(NodeDeleteAction.java:103)
at
org.jenmo.core.repository.del.NodeDeleteAction.delete(NodeDeleteAction.java:1)
at org.jenmo.core.repository.DefaultDaoJPA.delete(DefaultDaoJPA.java:77)
at
org.jenmo.core.domain.TestDbDeleteBug.testDelete(TestDbDeleteBug.java:69)
Indeed this is what I have in my fetchOutputs method:
first time (OK): org.jenmo.core.domain.n...@26556949(pk=100)
second time (!OK): [150, 1, 10]
Thanks a lot for your help!
andiqo
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