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@Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface OneToMany
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.example.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;}
Optional Element Summary | |
---|---|
CascadeType[] |
cascade
(Optional) The operations that must be cascaded to the target of the association. |
FetchType |
fetch
(Optional) Whether the association should be lazily loaded or must be eagerly fetched. |
java.lang.String |
mappedBy
The field that owns the relationship. |
boolean |
orphanRemoval
(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. |
java.lang.Class |
targetEntity
(Optional) The entity class that is the target of the association. |
public abstract java.lang.Class targetEntity
Defaults to the parameterized type of the collection when defined using generics.
public abstract CascadeType[] cascade
Defaults to no operations being cascaded.
When the target collection is a java.util.Map
, the cascade
element applies to the
map value.
public abstract FetchType fetch
public abstract java.lang.String mappedBy
public abstract boolean orphanRemoval
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Generated on 10-February-2011 12:41