javax.persistence.EntityResult Maven / Gradle / Ivy

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package javax.persistence;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * Used to map the SELECT clause of a SQL query to an entity result. If this annotation is used, the SQL statement should select all of the
 * columns that are mapped to the entity object. This should include foreign key columns to related entities. The results obtained when
 * insufficient data is available are undefined.
 * 
 *  *   Example:
 * 
 *   Query q = em.createNativeQuery(
 *       "SELECT o.id, o.quantity, o.item, i.id, i.name, i.description "+
 *           "FROM Order o, Item i " +
 *           "WHERE (o.quantity > 25) AND (o.item = i.id)",
 *       "OrderItemResults");
 *   @SqlResultSetMapping(name="OrderItemResults",
 *       entities={
 *           @EntityResult(entityClass=com.acme.Order.class),
 *           @EntityResult(entityClass=com.acme.Item.class)
 *   })
 * 
 * 
 * @see SqlResultSetMapping
 * 
 * @since Java Persistence 1.0
 */
@Target({})
@Retention(RUNTIME)
public @interface EntityResult {

	/**
	 * Specifies the column name (or alias) of the column in the SELECT list that is used to determine the type of the entity instance.
	 */
	String discriminatorColumn() default "";

	/**
	 * The class of the result.
	 */
	Class entityClass();

	/**
	 * Maps the columns specified in the SELECT list of the query to the properties or fields of the entity class.
	 */
	FieldResult[] fields() default {};
}