I have the following class structure:
@MappedSuperclass
public abstract class MyAbstract implements Cloneable {
@ElementCollection(fetch = FetchType.EAGER)
@OrderColumn(name = "index_in_list")
@NotFound(action = NotFoundAction.IGNORE)
protected List<ListElement> list = null;
}
@Entity
@Table(name = "entity_1")
@AssociationOverrides({
@AssociationOverride(name = "list", joinColumns = @JoinColumn(name = "id_entity_1", nullable = false))
})
public class Entity1 extends MyAbstract {
}
@Entity
@Table(name = "entity_2")
@AssociationOverrides({
@AssociationOverride(name = "list", joinColumns = @JoinColumn(name = "id_entity_2", nullable = false))
})
public class Entity2 extends MyAbstract {
}
As you can see I have two classes which have the same field (a list). I want to map the classes to its own tables. The relation is unidirectional. ListElement's table has both fields: id_entity_1 and id_entity_2. Anyway I got the following error:
org.hibernate.AnnotationException: Illegal attempt to define a @JoinColumn with a mappedBy association: list
I decided to add @JoinColumn annotation to the field in abstract class:
@ElementCollection(fetch = FetchType.EAGER)
@JoinColumn
@OrderColumn(name = "index_in_list")
@NotFound(action = NotFoundAction.IGNORE)
protected List<ListElement> list = null;
But I got:
org.hibernate.MappingException: Duplicate property mapping of _listBackref found in ListElement
I used to do mapping in XML file but recently I decided to use annotations instead. Using XML everything worked perfectly. The XML structure was:
<class name="Entity1" table="entity_1">
<list name="list" cascade="all-delete-orphan">
<key column="id_entity_1" not-null="false"/>
<index column="index_in_list"/>
<one-to-many class="ListElement" not-found="ignore"/>
</list>
</class>
<class name="Entity2" table="entity_2">
<list name="list" cascade="all-delete-orphan">
<key column="id_entity_2"/>
<index column="index_in_list"/>
<one-to-many class="ListElement" not-found="ignore"/>
</list>
</class>
So, my question is: How to map such inheritance by annotations?
EDIT 1: ListElement
An extract of the definition is:
@Entity
@Table(name = "elements")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "discriminator", discriminatorType = DiscriminatorType.INTEGER)
public abstract class AbstractElement implements Cloneable {
@Id
@Column(name = "id_element")
@GeneratedValue(strategy = GenerationType.IDENTITY)
protected Long id = null;
@Column(name = "name", nullable = false, length = 255)
protected String name = null;
...and more simple properties
}
@Entity
@DiscriminatorValue("0")
public class ListElement extends AbstractElement {
@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
@JoinColumn(name = "id_parent", nullable = false)
@MapKeyColumn(name = "key_in_map", nullable = false)
@OrderColumn(name = "id_xxx")
private Map<String, Xxx> xxx = null;
@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
@JoinColumn(name = "id_parent", nullable = false)
@MapKeyColumn(name = "key_in_map", nullable = false)
@OrderColumn(name = "id_yyy")
private Map<String, Yyy> yyy = null;
...and methods
}
EDIT 2: OneToMany
I've replaced @ElementCollection by @OneToMany:
@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
@JoinColumn
@OrderColumn(name = "index_in_list")
protected List<ListElement> list = null;
and I got:
org.hibernate.MappingException: Duplicate property mapping of _listBackref found in ListElement
ListElement
is an entity. So you can't use it in a @ElementCollection
which, as its javadoc indicates,
Defines a collection of instances of a basic type or embeddable class
(emphasis mine)
What you want is @OneToMany
, since you have an association between two entities.
The @NotFound
doesn't make sense either on a toMany association. It's used when you have a toOne association mapped by a "foreign key" which doesn't reference any existing row.
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