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POGWT/RequestFactory/JPA foreign key not merged automatically
 

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    <p>I have the 2 following entities:</p> <pre><code>@Entity @Table(name = "brand") public class Brand { @Id @Column(name = "id") private Integer id; @Column(name = "name") private String name; } </code></pre> <p>and </p> <pre><code>@Entity @Table(name = "car") public class Car { @Id @Column(name = "id") private Integer id; @Version @Column(name = "version") private Integer version; @ManyToOne(optional=false) @JoinColumn(name = "brand_id", referencedColumnName = "id") private Brand brand; @Column(name = "otherproperty") private String otherProperty; } </code></pre> <p>Basically the brand will be a predefined list that <em>should</em> never change, chosen in the GUI from a drop-down list. However, I'd like to be able to change the brand of my car as any other property.</p> <p>Here is the method in my DAO:</p> <pre><code>public void updateCar(Car update) throws Exception { EntityManager em = entityManager(); try { em.getTransaction().begin(); em.merge(update); em.getTransaction().commit(); } finally { em.close(); } } </code></pre> <p>The DAO works fine to update <code>otherProperty</code>, but if I provide another brand as child of the <code>Car update</code> parameter, it won't update the foreign key to the new brand.</p> <p>I've tried using the <code>CascadeType</code> properties, but it wants to update the brand table, which I don't want.</p> <p>Any help would be appreciated. Thanks!</p> <hr> <p>EDIT: OK I've found a solution, but it looks over complicated to me.</p> <p>If I add 2 lines in the DAO code in order to explicitly look for the brand to update, it works:</p> <pre><code>public void updateCar(Car update) throws Exception { EntityManager em = entityManager(); try { em.getTransaction().begin(); Brand lookedUp = findBrandById(update.getBrand().getId()); update.setBrand(lookedUp); em.merge(update); em.getTransaction().commit(); } finally { em.close(); } } </code></pre> <p>However I'm working with GWT/RequestFactory, and have implemented a <code>Locator</code> for my <code>Brand</code> and one for my <code>Car</code>, so I would assume the <code>Locator</code> would take care of that business for me.</p> <p>Am I missing something?</p>
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