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POJPA, compound key with foreign keys + persist oneToMany
 

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  1. POJPA, compound key with foreign keys + persist oneToMany
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    <p>I'm trying to do something with JPA that'll use a lot on a project but I'm stuck.</p> <p>I have 2 entities + a kind of "glue" entity, I'll call them</p> <ul> <li>ClassA</li> <li>ClassB</li> <li>Glue</li> </ul> <p>I want to add a new ClassA with new Glues set in it's list, ClassB's already exist.</p> <p>That would do something like :</p> <pre> ClassA 1 | Glue 1 1 | ClassB 1 ClassA 1 | Glue 1 2 | ClassB 2 ClassA 1 | Glue 1 3 | ClassB 3 ClassA 1 | Glue 1 4 | ClassB 4 </pre> <p>So as said ClassA and all Glues are to be inserted, ClassA has a List with the new Glues to be inserted.</p> <p>Here they are :</p> <pre><code>@Entity public class ClassA implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id; (...) @OneToMany(cascade = CascadeType.ALL, mappedBy = "classA") private List&lt;Glue&gt; glueList; (...) } @Entity public class ClassB implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id; (...) } @Entity public class Glue implements Serializable { @EmbeddedId protected GluePK gluePK; @JoinColumn(name = "id_class_a", referencedColumnName = "id", nullable = false, insertable = false, updatable = false) @ManyToOne(optional = false) private ClassA classA; @JoinColumn(name = "id_class_b", referencedColumnName = "id", nullable = false, insertable = false, updatable = false) @ManyToOne(optional = false) private ClassB classB; (...) } @Embeddable public class GluePK implements Serializable { @Basic(optional = false) @NotNull @Column(name = "id_class_a", nullable = false) private int idClassA; @Basic(optional = false) @NotNull @Column(name = "id_class_b", nullable = false) private int idClassB; (...) } </code></pre> <p>When I try to persist my ClassA I'm getting something like :</p> <p>com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (<code>bdd</code>.<code>glue</code>, CONSTRAINT <code>constraint_name</code> FOREIGN KEY (<code>id_class_a</code>) REFERENCES <code>ClassA</code> (<code>id</code>) ON DELETE NO ACTION ON UPDATE NO ACTION)</p> <p>I understand that he complains that Glues dont have ClassA's reference set but I'd like him to fill it just then he persists ClassA.</p> <p>Is this achievable? If not what's the best way to do it?</p> <p>I'd like to stay on JPA without any specific vendor tricks (I'm using eclipselink) but if some vendor can do it easily I'll go for it.</p> <p>Thanks!</p>
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    1. USAlexandre Jacob
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