CompoundIdentity is not supported

[dhakehurst]

version: 5.1.0-m1
test case: https://github.com/dhakehurst/test-jdo, SimpleTest.CompoundIdentity()

Error from stacktrace indicates a badly formed CYPHER statement

"START pc=node:DN_TYPES(class="mydomain.model.CompoundItem") WHERE (pc.id = "item1" and pc.owner = cont1) RETURN pc"

maybe missing quotes around the "cont1".

I think that the problem might be the if statement at line 193 of Neo4jUtils.
it tests if the storedValue is an instance of a String, and inserts quotes if so, else no quotes.
However, in the case of the compound PK, the PK is stored as a String (I think).

So an additional test to catch the PK case needs to be added.
Am not sure how to test for the PK case, happy to provide a patch if I can get some advice.

[dhakehurst]

possible patch

replace line 193:
if (storedValue instanceof String)
with:
if (storedValue instanceof String || !cmd.usesSingleFieldIdentityClass())

this enables the compound identity to work, but not sure if it breaks any other situations
it shouldn't do, but I don't have a large test suit to check it on.

[andyjefferson]

That is not a possible patch because a relation field is not stored as a Neo4j "property", instead as a Relation, as per https://github.com/datanucleus/datanucleus-neo4j/blob/master/src/main/java/org/datanucleus/store/neo4j/fieldmanager/StoreFieldManager.java#L417 . Consequently to check for existence of an object which has a relation as a PK field then you will need to do a different query, and cannot simply check on properties.