JPA Annotation

ConstructorResult

Implemented Interfaces:
Annotation

Used in conjunction with the SqlResultSetMapping annotation to map the SELECT clause of a SQL query to a constructor.

Applies a constructor for the target class, passing in as arguments values from the specified columns. All columns corresponding to arguments of the intended constructor must be specified using the columns element of the ConstructorResult annotation in the same order as that of the argument list of the constructor. Any entities returned as constructor results will be in either the new or detached state, depending on whether a primary key is retrieved for the constructed object.

Example:
   Query q = em.createNativeQuery(
      "SELECT c.id, c.name, COUNT(o) as orderCount, AVG(o.price) AS avgOrder " +
      "FROM Customer c, Orders o " +
      "WHERE o.cid = c.id " +
      "GROUP BY c.id, c.name",
      "CustomerDetailsResult");

   @SqlResultSetMapping(
       name="CustomerDetailsResult",
       classes={
          @ConstructorResult(
               targetClass=com.acme.CustomerDetails.class,
                 columns={
                    @ColumnResult(name="id"),
                    @ColumnResult(name="name"),
                    @ColumnResult(name="orderCount"),
                    @ColumnResult(name="avgOrder", type=Double.class)
                    }
          )
       }
      )
See Also:
SqlResultSetMapping
ColumnResult
Since:
JPA 2.1

Public Annotation Attributes

ColumnResult[] columns default null
(Required) The mapping of columns in the SELECT list to the arguments of the intended constructor, in order.
Since:
JPA 2.1
Class targetClass default null
(Required) The class whose constructor is to be invoked.
Since:
JPA 2.1