javax.persistence

Annotation Type ConstructorResult

@Target(value={})
@Retention(value=RUNTIME)
public @interface ConstructorResult

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)
                    }
          )
       }
      )

 

Since:

Java Persistence 2.1

See Also:

SqlResultSetMapping, ColumnResult

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
ColumnResult[]	columns (Required) The mapping of columns in the SELECT list to the arguments of the intended constructor, in order.
Class	targetClass (Required) The class whose constructor is to be invoked.

Element Detail

targetClass

public abstract Class targetClass

(Required) The class whose constructor is to be invoked.

columns

public abstract ColumnResult[] columns

(Required) The mapping of columns in the SELECT list to the arguments of the intended constructor, in order.