TYPE() function problem

[tovarisch <is...@gmail.com>]

Hi all,

I'm starting with JPA and I found a strange behaviour using TYPE() function
and inherited classes.

Let's have two hierarchical classes:


@Entity
@Table(name="nodes")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="type",
discriminatorType=DiscriminatorType.STRING)
public abstract class Node implements Serializable {

	@Id	
	@GeneratedValue(strategy=GenerationType.TABLE, generator="node")
	@TableGenerator(name="node", table="idgenerator", pkColumnName="generator",
valueColumnName="lastId", pkColumnValue="node" )
	@Column(name="id")
	private long id;
	
	@ManyToOne
	@JoinColumn(name="parentId")
	private Node parent;

	@OneToMany(mappedBy="parent", cascade=CascadeType.ALL)
	@OrderColumn(name="childIndex")
	private List<Node> children;


	/* getters & setters & logic methods*/

}


@Entity
@DiscriminatorValue(value="F")
public class Folder extends Node implements Serializable {

	/* ...*/

	
}


The query
 
    SELECT n FROM Node n WHERE TYPE(n)=Folder

generates the following SQL:

    SELECT t0.id, t0.type, t1.id, t1.type 
    FROM nodes t0 LEFT OUTER JOIN nodes t1 ON t0.parentId = t1.id WHERE
(t0.type = 'F')


but this query:

    SELECT n FROM Node n WHERE TYPE(n.parent)=Folder

generates exactly the same SQL, returning the nodes that are folders,
instead of the nodes which parent is a folder.

Reading the spec I understand that this last query is valid. Am I doing
something wrong?

Thanks.

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Re: SQL generated by TYPE() function

[Michael Dick <mi...@gmail.com>]

Looks correct to me. There's a similar example in 
https://fisheye6.atlassian.com/browse/openjpa/tags/2.1.0/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/inheritance/polymorphic/TestTablePerClassInheritanceWithAbstractRoot.java?r=1071316
this testcase  (line 203). 

-mike

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Re: SQL generated by TYPE() function

[tovarisch <is...@gmail.com>]

Hi all,

Could anyone confirm that the query is correct? 

    SELECT n FROM Node n WHERE TYPE(n.parent)=Folder 

Thank you very much.


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