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@Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface MapKeyJoinColumn
Specifies a mapping to an entity that is a map key. The map key
join column is in the collection table, join table, or table of the
target entity that is used to represent the map. If no
MapKeyJoinColumn
annotation is specified, a single
join column is assumed and the default values apply.
Example 1: @Entity public class Company { @Id int id; ... @OneToMany // unidirectional @JoinTable(name="COMPANY_ORGANIZATION", joinColumns=@JoinColumn(name="COMPANY"), inverseJoinColumns=@JoinColumn(name="VICEPRESIDENT")) @MapKeyJoinColumn(name="DIVISION") Map<Division, VicePresident> organization; } Example 2: @Entity public class VideoStore { @Id int id; String name; Address location; ... @ElementCollection @CollectionTable(name="INVENTORY", joinColumns=@JoinColumn(name="STORE")) @Column(name="COPIES_IN_STOCK") @MapKeyJoinColumn(name="MOVIE", referencedColumnName="ID") Map<Movie, Integer> videoInventory; ... } @Entity public class Movie { @Id long id; String title; ... } Example 3: @Entity public class Student { @Id int studentId; ... @ManyToMany // students and courses are also many-many @JoinTable(name="ENROLLMENTS", joinColumns=@JoinColumn(name="STUDENT"), inverseJoinColumns=@JoinColumn(name="SEMESTER")) @MapKeyJoinColumn(name="COURSE") Map<Course, Semester> enrollment; ... }
Optional Element Summary | |
---|---|
java.lang.String |
columnDefinition
(Optional) The SQL fragment that is used when generating the DDL for the column. |
boolean |
insertable
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider. |
java.lang.String |
name
(Optional) The name of the foreign key column for the map key. |
boolean |
nullable
(Optional) Whether the foreign key column is nullable. |
java.lang.String |
referencedColumnName
(Optional) The name of the column referenced by this foreign key column. |
java.lang.String |
table
(Optional) The name of the table that contains the foreign key column. |
boolean |
unique
(Optional) Whether the property is a unique key. |
boolean |
updatable
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider. |
public abstract java.lang.String name
Default (only applies if a single join column is used.) The concatenation of the following: the name of the referencing relationship property or field of the referencing entity or embeddable class; "_"; "KEY".
public abstract java.lang.String referencedColumnName
Default (only applies if single join column is being used.) The same name as the primary key column of the referenced table
public abstract boolean unique
UniqueConstraint
annotation
at the table level and is useful for when the unique key
constraint is only a single field.
public abstract boolean nullable
public abstract boolean insertable
public abstract boolean updatable
public abstract java.lang.String columnDefinition
public abstract java.lang.String table
Default:
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Generated on 10-February-2011 12:41