javax.persistence.OneToMany Maven / Gradle / Ivy
package javax.persistence;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.FetchType.LAZY;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
/**
* Defines a many-valued association with one-to-many multiplicity.
*
*
* If the collection is defined using generics to specify the element type, the associated target entity type need not be specified;
* otherwise the target entity class must be specified. If the relationship is bidirectional, the mappedBy element must be
* used to specify the relationship field or property of the entity that is the owner of the relationship.
*
*
* The OneToMany annotation may be used within an embeddable class contained within an entity class to specify a relationship
* to a collection of entities. If the relationship is bidirectional, the mappedBy element must be used to specify the
* relationship field or property of the entity that is the owner of the relationship.
*
* When the collection is a java.util.Map, the cascade element and the orphanRemoval element apply to
* the map value.
*
*
*
* Example 1: One-to-Many association using generics
*
* // In Customer class:
*
* @OneToMany(cascade=ALL, mappedBy="customer")
* public Set<Order> getOrders() { return orders; }
*
* In Order class:
*
* @ManyToOne
* @JoinColumn(name="CUST_ID", nullable=false)
* public Customer getCustomer() { return customer; }
*
*
* Example 2: One-to-Many association without using generics
*
* // In Customer class:
*
* @OneToMany(targetEntity=com.acme.Order.class, cascade=ALL,
* mappedBy="customer")
* public Set getOrders() { return orders; }
*
* // In Order class:
*
* @ManyToOne
* @JoinColumn(name="CUST_ID", nullable=false)
* public Customer getCustomer() { return customer; }
*
*
* Example 3: Unidirectional One-to-Many association using a foreign key mapping
*
* // In Customer class:
*
* @OneToMany(orphanRemoval=true)
* @JoinColumn(name="CUST_ID") // join column is in table for Order
* public Set<Order> getOrders() {return orders;}
*
*
*
* @since Java Persistence 1.0
*/
@Target({ METHOD, FIELD })
@Retention(RUNTIME)
public @interface OneToMany {
/**
* (Optional) The operations that must be cascaded to the target of the association.
*
* Defaults to no operations being cascaded.
*
*
* When the target collection is a {@link java.util.Map java.util.Map}, the cascade element applies to the map value.
*/
CascadeType[] cascade() default {};
/**
* (Optional) Whether the association should be lazily loaded or must be eagerly fetched. The EAGER strategy is a requirement on the
* persistence provider runtime that the associated entities must be eagerly fetched. The LAZY strategy is a hint to the persistence
* provider runtime.
*/
FetchType fetch() default LAZY;
/**
* The field that owns the relationship. Required unless the relationship is unidirectional.
*/
String mappedBy() default "";
/**
* (Optional) Whether to apply the remove operation to entities that have been removed from the relationship and to cascade the remove
* operation to those entities.
*
* @since Java Persistence 2.0
*/
boolean orphanRemoval() default false;
/**
* (Optional) The entity class that is the target of the association. Optional only if the collection property is defined using Java
* generics. Must be specified otherwise.
*
*
* Defaults to the parameterized type of the collection when defined using generics.
*/
Class targetEntity() default void.class;
}