Composite property issue: removing entry doesn't work

[gonzalad]

Hello,

I'm using SDN 6.2.0.

When I remove an entry from a composite property.
Then I expect the entry to be removed from the database node.
But the entry is not removed.

I think the issue originates from the Neo4j query generated by SDN in CypherGenerator#prepareSaveOf (I assume the += in the second match):

OPTIONAL MATCH (hlp:`Sample`) WHERE id(hlp) = $__id__ WITH hlp
WHERE hlp IS NULL CREATE (sampleEntity:`Sample`) SET sampleEntity = $__properties__ RETURN sampleEntity 
UNION
MATCH (sampleEntity:`Sample`) WHERE id(sampleEntity) = $__id__ SET sampleEntity += $__properties__ RETURN sampleEntity

Thanks !

Sample

@Node("Sample")
public class SampleEntity {


    @GeneratedValue
    @Id
    private Long id;

    private String name;

    @CompositeProperty(prefix = "somePrefix")
    private Map<String, Object> composite = new HashMap<>();

   ...getters/setters...
}

Test case:

@SpringBootTest
class Sdn6Test {

    @Autowired
    private SampleRepository sampleRepository;

    @Test
    void removeEntryInCompositePropertyShouldRemoveEntryInDb() {

        Map composite = new HashMap(Map.ofEntries(
            Map.entry("entry1", "value1"),
            Map.entry("entry2", "value2")
        ));
        SampleEntity entity = createSample(composite);
        // removing a single entry 
        entity.getComposite().remove("entry1");
        sampleRepository.save(entity);

        Optional<SampleEntity> entityInDatabase = sampleRepository.findById(entity.getId());

         // **error** returns 2 instead of 1
        assertThat(entityInDatabase.orElseThrow().getComposite()).hasSize(1);
    }

    private SampleEntity createSample(Map composite) {
        SampleEntity entity = new SampleEntity();
        entity.setName("sample");
        entity.setComposite(new HashMap<>(composite));
        return sampleRepository.save(entity);
    }
}

Reproducing the issue

The issue can be reproduced by running the unit test from this sample project:

https://github.com/gonzalad/sdn6-tests/tree/issue-composite-properties by running the unit test: Sdn6Test#removeEntryInCompositePropertyShouldRemoveEntryInDb (https://github.com/gonzalad/sdn6-tests/blob/issue-composite-properties/src/test/java/com/example/sdn6/Sdn6Test.java#L29)

[michael-simons]

Hi @gonzalad thanks for taking the time to fill an issue.

This one is a duplicate of #2280.

Elements in a composite property must be set explicitly to literal null or to Values.NULL to be removed.
This can be done either in a custom converter if you run such a thing for your entity or in client code such as in your case.

Why is that? Because SDN6 is "session free" or in other words, it doesn't keep a cache of your loaded entities around and therefor does not know what was there when an entity was loaded.

In Neo4j null properties are equivalent to non-existing properties.

Therefor your test can be fixed like this:

@Test
void removeEntryInCompositePropertyShouldRemoveEntryInDb() {

    Map composite = new HashMap(Map.ofEntries(
        Map.entry("entry1", "value1"),
        Map.entry("entry2", "value2")
    ));
    SampleEntity entity = createSample(composite);
    assertThat(entity.getComposite()).hasSize(2);
    entity.getComposite().put("entry1", null);
    sampleRepository.save(entity);

    Optional<SampleEntity> entityInDatabase = sampleRepository.findById(entity.getId());

    assertThat(entityInDatabase)
        .isPresent()
        .hasValueSatisfying(v -> {
            assertThat(v.getName()).isEqualTo(entity.getName());
            assertThat(v.getComposite())
                .hasSize(1)
                .containsEntry("entry2", Values.value("value2"));
        });
}

I personally would add a method such as removeEntry(String key to your entity for this purpose and inside that method doing what I did in the test (entity.getComposite().put("entry1", null);)

[gonzalad]

Thanks @michael-simons, sorry I missed the initial issue !

[michael-simons]

My pleasure, and no problem.