Until today we relied on the return value Neo4jRepository.save as an confirmation that update was successful but it seems that the returned entity does not reflect the persisted state. In our case updates on relations never got persisted.
This is a example of one of our relations:
@RelationshipEntity(type = "responsible_for_product")
@Data
public class ProductResponsibleUnitRelation {
@Id
@GeneratedValue
private Long id;
@StartNode
private LegalEntityNode legalEntity;
@EndNode
private ProductHierarchyNode productHierarchy;
private LocalDate validFrom;
private LocalDate validTo;
}
@NodeEntity
@Data
public class LegalEntityNode {
@Id
private String legalEntityId;
}
@NodeEntity
@Data
public class ProductHierarchyNode {
@Id
private String id;
}
I created a integration test that was fine as long as i checked only the entity returned by save (in JPA test i mostly use saveAndFlush) now it is failing:
@Autowired
private ProductResponsibleUnitRepository repository;
@Test
public void crudTest() {
//create
ProductHierarchyNode productHierarchyNode = random(ProductHierarchyNode.class);
productHierarchyNode.setId("123-456-789");
LegalEntityNode legalEntityNode = random(LegalEntityNode.class);
legalEntityNode.setLegalEntityId("1");
ProductResponsibleUnitRelation productResponsibleUnitRelation = new ProductResponsibleUnitRelation();
productResponsibleUnitRelation.setProductHierarchy(productHierarchyNode);
productResponsibleUnitRelation.setLegalEntity(legalEntityNode);
productResponsibleUnitRelation.setValidFrom(LocalDate.now());
productResponsibleUnitRelation.setValidTo(LocalDate.now().plusYears(1));
ProductResponsibleUnitRelation savedPru = repository.save(productResponsibleUnitRelation);
Long id = savedPru.getId();
assertNotNull(id);
//read
Optional<ProductResponsibleUnitRelation> readPruOptional = repository.findById(id);
assertTrue(readPruOptional.isPresent());
assertThat(readPruOptional.get(), is(savedPru));
//update
ProductHierarchyNode productHierarchyNode1 = new ProductHierarchyNode();
String newPhId = "4711";
productHierarchyNode1.setId(newPhId);
productResponsibleUnitRelation.setProductHierarchy(productHierarchyNode1);
repository.save(productResponsibleUnitRelation);
Optional<ProductResponsibleUnitRelation> readPruOptionalUpdated = repository.findById(id);
assertTrue(readPruOptionalUpdated.isPresent());
// THIS IS FAILING - still "123-456-789" the relation is still connected to "123-456-789"
assertThat(readPruOptionalUpdated.get().getProductHierarchy(), is(productHierarchyNode1));
//delete
repository.deleteById(id);
assertFalse(repository.findById(id).isPresent());
}
While the new productHierarchyNode1 is persisted correctly it is not connected/ no part of the realation:
After correct save "1" should be "responsible for" "4711"
This is not only happening in tests but also in "real" - interacting through service and rest layer with the repository.
So how to get updating relations (especially changing start and end node) working
I found a partial(?) solution for your problem:
The underlying mechanism creates a second ProductResponsibleUnitRelation relationship when the second save occurs. Neo4j-OGM does not consider this as an existing relationship because the start or end nodes has changed. You can see the state when you skip the deletion at the end of the test.
This also means that the id you are trying to get the new information from is the old one. So this is the reason why the test is failing.
Long newId = repository.save(productResponsibleUnitRelation).getId();
Optional<ProductResponsibleUnitRelation> readPruOptionalUpdated = repository.findById(newId);
assertThat(pru.get().getProductHierarchy(), is(newProductNode));
As I said in my previous answer working directly with relationship entities is a little bit more challenging 
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