neo4j: user defined procedure exception “Write operations are not allowed for `READ` transactions”

Question

I have implemented a user defined procedure using the example template .

The procedure is annotated using "@Procedure(value = "foo.bar", mode = Mode.WRITE)", nevertheless, when I try to execute an operation on a Node instance that modifies the graph, it fails with "Write operations are not allowed for READ transactions".

The node instance was obtained via db.findNode (...), and the write-operation that I am attempting to execute is nodeinstance.createRelationshipTo (...)

Interestingly, the code works fine when run in the context of the neo4j testing harness.

Any help greatly appreciated!

Answer 1

From inspecting the APOC user defined procedures, I learned the answer. I am using neo4j 3.0.7, for 3.0.xa procedure that wants to write to the graph must be annotated with "@PerformsWrites", as well as "@Procedure". The mode argument", mode = Mode.WRITE", is for 3.1, and "@PerformsWrites" is for 3.0.x -- learned this from Stefan Armbruster