[hibernate-issues] [Hibernate-JIRA] Created: (HHH-5136) map-key-column is broken

[Harald Wellmann (JIRA)]

map-key-column is broken
------------------------

                 Key: HHH-5136
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5136
             Project: Hibernate Core
          Issue Type: Bug
    Affects Versions: 3.5.1
         Environment: Hibernate 3.5.1, PostgreSQL 8.4.3
            Reporter: Harald Wellmann
            Priority: Critical


I have an entity with a Map<String, Embeddable> with unexpected behaviour. The problem is that annotation mappings and the equivalent XML mappings yield different results. (For brevity, I'm leaving out the getters and setters and the SQL constraints in the following examples.)

Here is my Embeddable:

{code:java}
@Embeddable
public class LocalizedString
{
    private String language;
    private String text;
}
{code}

And this is the containing entity:

{code:java}
@Entity
public class Amenity 
{
    @Id
    @Column(name = "amenity_id")
    @GeneratedValue
    private long id;

    @ElementCollection
    @CollectionTable(name = "amenity_name", joinColumns = @JoinColumn(name = "amenity_id"))
    @MapKeyColumn(name = "language_map_key")
    private Map<String, LocalizedString> names = new HashMap<String, LocalizedString>();
}

{code}

Hibernate generates the following collection table:

{code:sql}
CREATE TABLE amenity_name
(
  amenity_id bigint NOT NULL,
  "language" character varying(255),
  "text" character varying(255),
  language_map_key character varying(255) NOT NULL
)
{code}


Now when replacing the annotations by the following XML mapping

{code:xml}
<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings version="2.0"
	xmlns="http://java.sun.com/xml/ns/persistence/orm" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/orm_2_0.xsd">
	<entity class="Amenity">
		<attributes>
			<id name="id">
				<column name="amenity_id"/>
				<generated-value />				
			</id>
			<element-collection name="names">
				<map-key-column name="language_map_key" />
				<collection-table name="amenity_name">				
					<join-column name="amenity_id" referenced-column-name="amenity_id"/>
				</collection-table>
			</element-collection>
		</attributes>
	</entity>
	<embeddable class="LocalizedString">
	  <attributes>
	    <basic name="language"></basic>
	    <basic name="text"></basic>
	  </attributes>
	</embeddable>
</entity-mappings>
{code}

the generated SQL looks like this:

{code:sql}
CREATE TABLE amenity_names
(
  amenity_amenity_id bigint NOT NULL,
  "language" character varying(255),
  "text" character varying(255),
  names_key character varying(255) NOT NULL
)

{code}

It seems that the map-key-column and collection-table settings are simply ignored.

Another question: The column language_map_key is actually redundant, I would like to use the language column as map key instead. The JPA 2.0 spec is a bit vague on this case. When the map value is an entity, @MapKey can be used to select a property of the entity value as map key, but it is not clear to me whether the spec supports supressing the separate key column when the map value is an embeddable.

I tried using @MapKeyColumn(name="language"), but then Hibernate complained about a duplicate column.

Eclipselink (the version contained in Glassfish v3) accepts this usage and suppresses the duplicate column, i.e. the join table has the form

{code:sql}
CREATE TABLE amenity_name
(
  amenity_id bigint NOT NULL,
  "language" character varying(255),
  "text" character varying(255)
)
{code}


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