Updating titan vertex property using rexster rexpro failing - cassandra

Question

I am using titan 0.4.2 with cassandra 2.0.7 as the storage back end. I have used rexter-server 2.4.0 to insert vertex in the titan. However while i am trying to update a vertex property using rexter client I am getting null pointer exception.
RexsterClient client = RexsterClientFactory.open("localhost", "titangraph");
client.execute("g.getVertex(8).setProperty('name','William')");
The above code is throwing null pointer exception. However the script g.getVertex(8).setProperty('name','William') runs perfectly fine in the gremlin console
How can i update titan vertex property using rexster rexpro?

Answer 1

I will assume that you are saying the NullPointerException (NPE) is coming from the script executed on the server-side. In other words, the problem is a result of running:
g.getVertex(8).setProperty('name','William')
and not something in the client instantiation or related to other client side code beyond the script itself.
With that assumption in mind, I could not recreate your error. The execute method does return a list with a single null within it but I don't think you're referring to that as your problem given the assumption. So, there's really only two things that could be wrong that I can think of:
The vertex returned by g.v(8) does not exist and it returns null
g is null
To verify, just execute g.v(8). If it returns null then item one above is the issue. If you still get an NPE then item two above is the problem. If item two is the problem then the name of the graph you are referencing, titangraph, is either not right or there is a bug in Rexster's handling of that binding. To figure that out, execute this instead:
g = rexster.getGraph('titangraph')
g.v(8)
If you still have a NPE then I'd have to say that you need to check your rexster.xml more carefully regarding your configuration. If it works, then you should likely report a bug in Rexster.