javax.persistence
Annotation Type AssociationOverride


@Target(value={TYPE,METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface AssociationOverride

Used to override a mapping for an entity relationship.

May be applied to an entity that extends a mapped superclass to override a relationship mapping defined by the mapped superclass. If not specified, the association is mapped the same as in the original mapping. When used to override a mapping defined by a mapped superclass, AssociationOverride is applied to the entity class.

May be used to override a relationship mapping from an embeddable within an entity to another entity when the embeddable is on the owning side of the relationship. When used to override a relationship mapping defined by an embeddable class (including an embeddable class embedded within another embeddable class), AssociationOverride is applied to the field or property containing the embeddable.

When AssociationOverride is used to override a relationship mapping from an embeddable class, the name element specifies the referencing relationship field or property within the embeddable class. To override mappings at multiple levels of embedding, a dot (".") notation syntax must be used in the name element to indicate an attribute within an embedded attribute. The value of each identifier used with the dot notation is the name of the respective embedded field or property.

When AssociationOverride is applied to override the mappings of an embeddable class used as a map value, "value." must be used to prefix the name of the attribute within the embeddable class that is being overridden in order to specify it as part of the map value.

If the relationship mapping is a foreign key mapping, the joinColumns element is used. If the relationship mapping uses a join table, the joinTable element must be specified to override the mapping of the join table and/or its join columns.

    Example 1: Overriding the mapping of a relationship defined by a mapped superclass

    @MappedSuperclass
    public class Employee {
        ...
        @ManyToOne
        protected Address address;
        ...
    }
    
    @Entity 
        @AssociationOverride(name="address", 
                             joinColumns=@JoinColumn(name="ADDR_ID"))
        // address field mapping overridden to ADDR_ID foreign key
    public class PartTimeEmployee extends Employee {
        ...
    }
 
    Example 2: Overriding the mapping for phoneNumbers defined in the ContactInfo class

    @Entity
    public class Employee {
        @Id int id;
        @AssociationOverride(
          name="phoneNumbers",
          joinTable=@JoinTable(
             name="EMPPHONES",
             joinColumns=@JoinColumn(name="EMP"),
             inverseJoinColumns=@JoinColumn(name="PHONE")
          )
        )
        @Embedded ContactInfo contactInfo;
       ...
    }
 
    @Embeddable
    public class ContactInfo {
        @ManyToOne Address address; // Unidirectional
        @ManyToMany(targetEntity=PhoneNumber.class) List phoneNumbers;
    }
 
    @Entity
    public class PhoneNumber {
        @Id int number;
        @ManyToMany(mappedBy="contactInfo.phoneNumbers")
        Collection<Employee> employees;
     }
    

Since:
Java Persistence 1.0
See Also:
Embedded, Embeddable, MappedSuperclass, AttributeOverride

Required Element Summary
 java.lang.String name
          (Required) The name of the relationship property whose mapping is being overridden if property-based access is being used, or the name of the relationship field if field-based access is used.
 
Optional Element Summary
 JoinColumn[] joinColumns
          The join column(s) being mapped to the persistent attribute(s).
 JoinTable joinTable
          The join table that maps the relationship.
 

Element Detail

name

public abstract java.lang.String name
(Required) The name of the relationship property whose mapping is being overridden if property-based access is being used, or the name of the relationship field if field-based access is used.

joinColumns

public abstract JoinColumn[] joinColumns
The join column(s) being mapped to the persistent attribute(s). The joinColumns elements must be specified if a foreign key mapping is used in the overriding of the mapping of the relationship. The joinColumns element must not be specified if a join table is used in the overriding of the mapping of the relationship.

Default:
{}

joinTable

public abstract JoinTable joinTable
The join table that maps the relationship. The joinTable element must be specified if a join table is used in the overriding of the mapping of the relationship. The joinTable element must not be specified if a foreign key mapping is used in the overriding of the relationship.

Since:
Java Persistence 2.0
Default:
@javax.persistence.JoinTable


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Generated on 10-February-2011 12:41


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