Note: This ORM/SQL annotation is silently ignored by ObjectDB

799 words

javax.persistence.CollectionTable - JPA annotation

javax.persistence
Annotation CollectionTable

Target:
Fields (including property get methods)
Specifies the table that is used for the mapping of collections of basic or embeddable types. Applied to the collection-valued field or property.

By default, the columns of the collection table that correspond to the embeddable class or basic type are derived from the attributes of the embeddable class or from the basic type according to the default values of the Column annotation. In the case of a basic type, the column name is derived from the name of the collection-valued field or property. In the case of an embeddable class, the column names are derived from the field or property names of the embeddable class.

  • To override the default properties of the column used for a basic type, the Column annotation is used on the collection-valued attribute in addition to the ElementCollection annotation.
  • To override these defaults for an embeddable class, the AttributeOverride and/or AttributeOverrides annotations can be used in addition to the ElementCollection annotation. If the embeddable class contains references to other entities, the default values for the columns corresponding to those references may be overridden by means of the AssociationOverride and/or AssociationOverrides annotations.

If the CollectionTable annotation is missing, the default values of the CollectionTable annotation elements apply.

Example:

    @Embeddable public class Address {
       protected String street;
       protected String city;
       protected String state;
       ... 
     }
 
    @Entity public class Person {
       @Id protected String ssn;
       protected String name;
       protected Address home;
       ...
       @ElementCollection  // use default table (PERSON_NICKNAMES)
       @Column(name="name", length=50)
       protected Set<String> nickNames = new HashSet();
       ...
    }
 
    @Entity public class WealthyPerson extends Person {
       @ElementCollection
       @CollectionTable(name="HOMES") // use default join column name
       @AttributeOverrides({
          @AttributeOverride(name="street", 
                             column=@Column(name="HOME_STREET")),
          @AttributeOverride(name="city", 
                             column=@Column(name="HOME_CITY")),
          @AttributeOverride(name="state", 
                             column=@Column(name="HOME_STATE"))
        })
       protected Set<Address> vacationHomes = new HashSet();
       ...
    }

Since:
JPA 2.0
See Also:
ElementCollection
AttributeOverride
AssociationOverride
Column
String catalog
(Optional) The catalog of the table.
(Optional) The catalog of the table. If not specified, the default catalog is used.
Default value:
""
Since:
JPA 2.0
(Optional) The foreign key columns of the collection table which reference the primary table of the entity.
(Optional) The foreign key columns of the collection table which reference the primary table of the entity. The default only applies if a single join column is used. The default is the same as for JoinColumn (i.e., the concatenation of the following: the name of the entity; "_"; the name of the referenced primary key column.) However, if there is more than one join column, a JoinColumn annotation must be specified for each join column using the JoinColumns annotation. In this case, both the name and the referencedColumnName elements must be specified in each such JoinColumn annotation.
Default value:
{}
Since:
JPA 2.0
String name
(Optional) The name of the collection table.
(Optional) The name of the collection table. If not specified, it defaults to the concatenation of the name of the containing entity and the name of the collection attribute, separated by an underscore.
Default value:
""
Since:
JPA 2.0
String schema
(Optional) The schema of the table.
(Optional) The schema of the table. If not specified, the default schema for the user is used.
Default value:
""
Since:
JPA 2.0
(Optional) Unique constraints that are to be placed on the table.
(Optional) Unique constraints that are to be placed on the table. These are only used if table generation is in effect.
Default value:
{}
Since:
JPA 2.0

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.