JPA Annotation

MapKey

Target: METHOD, FIELD
Implemented Interfaces:
Annotation
Specifies the map key for associations of type java.util.Map when the map key is itself the primary key or a persistent field or property of the entity that is the value of the map.

If a persistent field or property other than the primary key is used as a map key then it is expected to have a uniqueness constraint associated with it.

The MapKeyClass annotation is not used when MapKey is specified and vice versa.

Example 1:

 {@snippet :
Since:
JPA 1.0

Public Annotation Attributes

String name default ""
(Optional) The name of the persistent field or property of the associated entity that is used as the map key.

Default: If the name element is not specified, the primary key of the associated entity is used as the map key. If the primary key is a composite primary key and is mapped as IdClass, an instance of the primary key class is used as the key.

Since:
JPA 1.0