JPA Annotation

MapKeyColumn

Target: METHOD, FIELD
Implemented Interfaces:
Annotation
Specifies the mapping for the key column of a map whose map key is a basic type. If the MapKeyColumn.name element is not specified, it defaults to the concatenation of the following: the name of the referencing relationship field or property; "_"; "KEY".

Example:

 {@snippet :
Since:
JPA 2.0

Public Annotation Attributes

String columnDefinition default ""
(Optional) The SQL fragment that is used when generating the DDL for the column.

Defaults to the generated SQL to create a column of the inferred type.

Since:
JPA 2.0
boolean insertable default true
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
Since:
JPA 2.0
int length default 255
(Optional) The column length.

Applies only to columns whose type is parameterized by length, for example, varchar or varbinary types.

Since:
JPA 2.0
String name default ""
(Optional) The name of the map key column.
The table in which it is found depends upon the context.
  • If the map key is for an element collection, the map key column is in the collection table for the map value.
  • If the map key is for a ManyToMany entity relationship or for a OneToMany entity relationship using a join table, the map key column is in a join table.
  • If the map key is for a OneToMany entity relationship using a foreign key mapping strategy, the map key column is in the table of the entity that is the value of the map.

Defaults to the concatenation of the following: the name of the referencing relationship field or property; "_"; "KEY".

Since:
JPA 2.0
boolean nullable default false
(Optional) Whether the database column is nullable.
Since:
JPA 2.0
String options default ""
(Optional) A SQL fragment appended to the generated DDL which declares this column.
May not be used in conjunction with MapKeyColumn.columnDefinition.
Since:
JPA 3.2
int precision default 0
(Optional) The precision for a column of SQL type decimal or numeric, or of similar database-native type.

Applies only to columns of exact numeric type.

The default value 0 indicates that a provider-determined precision should be inferred.

Since:
JPA 2.0
int scale default 0
(Optional) The scale for a column of SQL type decimal or numeric, or of similar database-native type.

Applies only to columns of exact numeric type.

The default value 0 indicates that a provider-determined precision should be inferred.

Since:
JPA 2.0
String table default ""
(Optional) The name of the table that contains the column.

Defaults: If the map key is for an element collection, the name of the collection table for the map value. If the map key is for a OneToMany or ManyToMany entity relationship using a join table, the name of the join table for the map. If the map key is for a OneToMany entity relationship using a foreign key mapping strategy, the name of the primary table of the entity that is the value of the map.

Since:
JPA 2.0
boolean unique default false
(Optional) Whether the column is a unique key.
This is a shortcut for the UniqueConstraint annotation at the table level and is useful for when the unique key constraint corresponds to only a single column. This constraint applies in addition to any constraint entailed by primary key mapping and to constraints specified at the table level.
Since:
JPA 2.0
boolean updatable default true
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
Since:
JPA 2.0