Question

I’m using JPA 2.0 and want to create a unique constraint using XML, not annotations.

The annotated class looks like this:

@Entity
public class Person {
    @Id
    @GeneratedValue
    private Long id;
    @Column(unique=true)
    private String name;

    // ..
}

And the orm.xml file like that – it’s missing the unique constraint though:

<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm orm_2_0.xsd"
    version="2.0">
    <entity class="kiosk.model.Person">
        <attributes>
            <id name="id">
                <generated-value strategy="AUTO" />
            </id>
            <basic name="name" />

            <!-- .. -->
        </attributes>
    </entity>
</entity-mappings>

How do I add a unique constraint to a JPA 2.0 class using XML?

Answer 1

<basic name="name">
    <column unique="true"/>
</basic>

See, http://en.wikibooks.org/wiki/Java_Persistence/Basic_Attributes