Jakarta EE 11.0.0 · jakarta.persistence.MapKeyColumn

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

Example:

@Entity
public class Item {
    @Id
    int id;
    ...
    @ElementCollection
    @MapKeyColumn(name = "IMAGE_NAME")
    @Column(name = "IMAGE_FILENAME")
    @CollectionTable(name = "IMAGE_MAPPING")
    Map<String, String> images;  // map from image name to filename
    ...
}

Method Summary

Modifier and Type	Method and Description
public String	columnDefinition() (Optional) The SQL fragment that is used when generating the DDL for the column.
public boolean	insertable() (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
public int	length() (Optional) The column length.
public String	name() (Optional) The name of the map key column.
public boolean	nullable() (Optional) Whether the database column is nullable.
public String	options() (Optional) A SQL fragment appended to the generated DDL which declares this column.
public int	precision() (Optional) The precision for a column of SQL type `decimal` or `numeric`, or of similar database-native type.
public int	scale() (Optional) The scale for a column of SQL type `decimal` or `numeric`, or of similar database-native type.
public String	table() (Optional) The name of the table that contains the column.
public boolean	unique() (Optional) Whether the column is a unique key.
public boolean	updatable() (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

Inherited from java.lang.annotation.Annotation:: annotationType equals hashCode toString

Method Detail

columnDefinition	back to summary
public String columnDefinition() (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.

columnDefinition

back to summary

public String columnDefinition()

(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.

insertable	back to summary
public boolean insertable() (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.

length back to summary

length	back to summary
public int length() (Optional) The column length. Applies only to columns whose type is parameterized by length, for example, `varchar` or `varbinary` types.

public int length()

(Optional) The column length.

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

name back to summary

name	back to summary
public String name() (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`".

public String name()

(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".

nullable	back to summary
public boolean nullable() (Optional) Whether the database column is nullable.

options back to summary

options	back to summary
public String options() (Optional) A SQL fragment appended to the generated DDL which declares this column. May not be used in conjunction with `columnDefinition()`. Since 3.2

public String options()

(Optional) A SQL fragment appended to the generated DDL which declares this column. May not be used in conjunction with columnDefinition().

Since: 3.2

precision back to summary

precision	back to summary
public int precision() (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.

public int precision()

(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.

scale back to summary

scale	back to summary
public int scale() (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.

public int scale()

(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.

table back to summary

table	back to summary
public String table() (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.

public String table()

(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.

unique	back to summary
public boolean unique() (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.

updatable	back to summary
public boolean updatable() (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

public @Interface MapKeyColumn

Method Summary

Method Detail