Passing Vertex as parameters in session.execute_graph()

[Jérôme Fuselier]

Hello,

I'm trying to use the DSE Graph API to interact with the Graph store but I find it quite challenging to understand the syntax of the Graph API using Gremlin statements from a Python script.

This works correctly:

res = session.execute_graph('''A = g.addV(label, 'A')[0]
                                            B = g.addV(label, 'B')[0]
                                            A.addEdge('edge', B)''')

But it's not very "Pythonic", if I want to create more complex queries I will end up working on building on the fly strings which is error-prone.

I'm trying to do something like that but it fails:

A = session.execute_graph('''g.addV(label, 'A')''')[0]
B = session.execute_graph('''g.addV(label, 'B')''')[0]
res = session.execute_graph('''A.addEdge('edge', B)''', {'A': A, 'B': B})

-> TypeError: Vertex({u'community_id': 516547968, u'~label': u'A', u'member_id': 512}, u'A', u'vertex', {}) is not JSON serializable


I don't know if that's a problem with the API or a problem with my vision on the usage of the API.

Thanks
Jerome

[Alan Boudreault]

Hello Jérome,

It seems that what you are looking for is the dse-graph package, which executes graph queries in a more Pythonic way using a Fluent API (with TinkerPop Gremlin).

Package: https://pypi.python.org/pypi/dse-graph/1.0.0

Getting Started: http://docs.datastax.com/en/developer/python-dse-graph/1.0.0/getting_started/

Regards,

Alan

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Alan Boudreault

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[Jérôme Fuselier]

Hi Alan,

Thanks for the information. I was a bit lost with what the different API provide. I will investigate the dse-graph package but the documentation seems pretty short. Can I find real world example somewhere ?

Best
Jerome

[Alan Boudreault]

Indeed, the dse-graph is only a connector to execute gremlin requests on a dse cluster. Here are some more complete graph documentation:

* DSE Graph: http://docs.datastax.com/en/dse/5.1/dse-dev/datastax_enterprise/graph/graphTOC.html

* TinkerPop/Gremlin: http://tinkerpop.apache.org/docs/current/reference/#intro

Alan

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