Neo4j: Inheritence - get correct child (type)

[MarkusSchulte]

Hi,

i am using Spring Data Neo4j, Snapshot.

I have two entities, where one is the motherclass:

@NodeEntity
ClassA {...}

@NodeEntity
ClassB extends ClassA {...}

When retrieving an entity, i am using neoTemplate.findOne(id, ClassA.class). Retrieved object is always of type ClassA. How do i get the object to be of type ClassB, if the object is of that kind? You see, i am searching for a kind of factory.

Greetz,
Markus

[lassewesth]

Markus,

You can do both casting and conversion, or projection(http://static.springsource.org/sprin...del:projection) depending on the situation:

@NodeEntity
class Foo {
    @GraphId
    Long id;
}

@NodeEntity
class Bar extends Foo {
    int baz;

    Bar() {
    }

    Bar(int baz) {
        this.baz = baz;
    }
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class InheritanceTests {
    @Configuration
    @EnableNeo4jRepositories
    static class TestConfig extends Neo4jConfiguration {
        @Bean
        GraphDatabaseService graphDatabaseService() {
            return new ImpermanentGraphDatabase();
        }
    }

    @Autowired
    Neo4jTemplate template;

    long id;

    @Before
    public void before() {
        Transaction transaction = template.getGraphDatabaseService().beginTx();

        id = template.save(new Bar(42)).id;

        transaction.success();
        transaction.finish();
    }

    @Test
    public void shouldFindSubclass() throws Exception {
        Bar bar = template.findOne(id, Bar.class);
        assertThat(bar.baz, is(42));

        Foo foo = template.findOne(id, Foo.class);
        assertThat(((Bar) foo).baz, is(42));

        bar = template.convert(foo, Bar.class);
        assertThat(bar.baz, is(42));
    }
}

[MarkusSchulte]

Scary.. and great ;-) Thank you!