Multiple representations of the same entity are being merged JPA

Question

Schema definition ``` CREATE TABLE person ( id bigint(20) NOT NULL AUTO_INCREMENT, PRIMARY KEY (id) ) ENGINE=InnoDB CREATE TABLE address ( person_id bigint(20) not null, postcode varchar(255) not null, state int(11), constraint `PRIMARY` primary key (address_id, postcode), constraint FK_dq8j32idfdnwny42fiovenqwo foreign key (person_id) references person (id) ) ENGINE=InnoDB ``` Ie a person should be able to have multiple addresses as long as the postcode is different. Classes ``` @Entity @Getter @Setter class Person implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) @Column(name="id", unique = true, nullable = false) private Long id; @OneToMany(cascade= CascadeType.ALL) private Set

Addresses = new HashSet<>(); protected Person(){} } @Entity @Getter @Setter class Address implements Serializable { @EmbeddedId private AddressId addressId; private State state; protected Address(){} } @Embeddable @Getter @Setter public class AddressId implements Serializab…

Accepted Answer

Address can be made an `@Embeddable` rather than an `@Entity`. In this scenario an Address has no persistent identity of its own which reflects your database: an address cannot exist without an associated person. The simplified mappings then look like: ``` @Entity @Getter @Setter class Person implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) @Column(name="id", unique = true, nullable = false) private Long id; @ElementCollection @CollectionTable(name = "address", joinColumns = @JoinColumn(name = "person_id")) private Set

Addresses = new HashSet<>(); protected Person(){} } @Embeddable @Getter @Setter class Address implements Serializable { private State state; private String postcode; protected Address(){} // override equals and hascode based on post code only // this will give you the desired behaviour } ``` If you override equals() and hashcode() based on post code then everything should work as expected. https://en.wikibooks.org/wiki/Java_Persistence/ElementCollection See also: Hibernate - @ElementCollection - Strange delete/insert behavior

Multiple representations of the same entity are being merged JPA

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