Automatically convert a parameter with Spring Data JPA

Question

In our entity beans we use a custom ID format which includes a checksum to verify that the ID is actually valid. Ids look like ID827391738979. To make sure that

Answer 1

You could use a custom type in your entity with JPA 2.1 @Convert, so JPA makes the conversion for you (I've tested it with Spring Data JPA also, and it worked transparently!), see:

Entity:

@Entity
class SomeEntity {

    @Column(name = "my_id_column_name")
    @Convert(converter = MyIDConverter.class)
    private ID itsID;
}

Converter:

public class MyIDConverter implements AttributeConverter<ID, String> {

    @Override
    public String convertToDatabaseColumn(ItStaticDataKey javaKey) {
        // your implementation here
    }

    @Override
    public ItStaticDataKey convertToEntityAttribute(final String databaseKey) {
        // your implementation here
    }

}

Notes:

1. Make sure you're using a JPA-2.1-compatible Spring Data JPA version. (I'm sure that Spring Data JPA 1.7.0 (and above) are (or at least should) be compatible).
2. Unfortunately, it won't work if that field should also be annotated with @Id.
3. If you use EclipseLink, you have to define converter in persistence.xml, or it doesn't pick it up. https://bugs.eclipse.org/bugs/show_bug.cgi?id=412454.
4. With JPA on Spring, package containing converters have to appear in property packageToScan on EntityManagerFactoryBean.