Class KeyExpression

  • All Implemented Interfaces:
    Expression

    public final class KeyExpression
    extends EncapsulatedIdentificationVariableExpression
    An identification variable qualified by the KEY operator is a path expression. The KEY operator may only be applied to identification variables that correspond to map-valued associations or map-valued element collections. The type of the path expression is the type computed as the result of the operation; that is, the abstract schema type of the field that is the value of the KEY operator (the map key).

    This is part of JPA 2.0.

    BNF: KEY(identification_variable)

    Version:
    2.5
    Author:
    Pascal Filion
    Since:
    2.3