gremlin python help with next() toList()

[Debasish Kanhar]

Hi,

I had a normal enviorenment of Gremlin Python + JanusGraph setup few days back, and my connection to JanusGraph was working like a charm. 

Now, I tried running basic queries, but it fails. Descriptions is as follows:

I start Cassandra & Elastic search. Then start bin/gremlin-server.sh

From python client I do the following:

from gremlin_python.structure.graph import Graph
from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection
url_for_graph = 'ws://{}:{}/gremlin'.format("127.0.0.1", "8182")
graph = Graph()
g = graph.traversal().withRemote(DriverRemoteConnection(url_for_graph, 'g'))
print(g.V().valueMap().next())

I got following traceback:

Traceback (most recent call last):

  File "/share/janusgraph-0.1.1-hadoop2/debasish/CodeBase/DataPreparation/DataPreparation.py", line 216, in <module>

    print(g.V().valueMap().next())

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 65, in next

    return self.__next__()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 38, in __next__

    self.traversal_strategies.apply_strategies(self)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 277, in apply_strategies

    traversal_strategy.apply(traversal)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/remote_connection.py", line 75, in apply

    remote_traversal = self.remote_connection.submit(traversal.bytecode)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 53, in submit

    traversers = self._loop.run_sync(lambda: self.submit_traversal_bytecode(request_id, bytecode))

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/ioloop.py", line 453, in run_sync

    return future_cell[0].result()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/concurrent.py", line 232, in result

    raise_exc_info(self._exc_info)

  File "<string>", line 3, in raise_exc_info

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 282, in wrapper

    yielded = next(result)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 69, in submit_traversal_bytecode

    "gremlin": self._graphson_writer.writeObject(bytecode),

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/structure/io/graphson.py", line 70, in writeObject

    return json.dumps(GraphSONWriter._dictify(objectData), separators=(',', ':'))

TypeError: 'separators' is an invalid keyword argument for this function

I realized this error is because of ujson. So I uninstalled ujson and ran again but this time a new error poped up.

Traceback (most recent call last):

  File "/share/janusgraph-0.1.1-hadoop2/debasish/CodeBase/DataPreparation/DataPreparation.py", line 216, in <module>

    print(g.V().valueMap().next())

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 65, in next

    return self.__next__()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 38, in __next__

    self.traversal_strategies.apply_strategies(self)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/process/traversal.py", line 277, in apply_strategies

    traversal_strategy.apply(traversal)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/remote_connection.py", line 75, in apply

    remote_traversal = self.remote_connection.submit(traversal.bytecode)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 53, in submit

    traversers = self._loop.run_sync(lambda: self.submit_traversal_bytecode(request_id, bytecode))

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/ioloop.py", line 453, in run_sync

    return future_cell[0].result()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/concurrent.py", line 232, in result

    raise_exc_info(self._exc_info)

  File "<string>", line 3, in raise_exc_info

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 1014, in run

    yielded = self.gen.throw(*exc_info)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 73, in submit_traversal_bytecode

    traversers = yield self._execute_message(message)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 1008, in run

    value = future.result()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/concurrent.py", line 232, in result

    raise_exc_info(self._exc_info)

  File "<string>", line 3, in raise_exc_info

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 1014, in run

    yielded = self.gen.throw(*exc_info)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 149, in _execute_message

    recv_message = yield response.receive()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 1008, in run

    value = future.result()

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/concurrent.py", line 232, in result

    raise_exc_info(self._exc_info)

  File "<string>", line 3, in raise_exc_info

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/tornado/gen.py", line 1017, in run

    yielded = self.gen.send(value)

  File "/home/prjadmin/anaconda3/lib/python3.6/site-packages/gremlin_python/driver/driver_remote_connection.py", line 229, in receive

    results.append(self._graphson_reader.toObject(item))

AttributeError: 'GraphSONReader' object has no attribute 'toObject'

The same set of errors were reported for .next() as well as .toList().

Did anything specific change in internal working of those methods in last few weeks? Or something I'm missing out on.

If required, do I need to attach my .properties, .yaml files? Or do I need to do clean setup?

Thanks

[Debasish Kanhar]

Adding to above points. the same issue can't be reproduced by executing queries by connecting gremlin server from bin/gremlin.sh

[Robert Dale]

Did you upgrade gremlin-python? Make sure you're using the right version which should be 3.2.3 for janusgraph-0.1.

Robert Dale

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[Debasish Kanhar]

Thanks for the input. I solved the issue yesterday itself. The issue was because somehow Tornado got updated from 4.1 to 4.3 and it was failing.

Robert Dale

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