Labelling Neo4j database using Neo4django

Question

This question is related to the github issue of Neo4django. I want to create multiple graphs using Neo4j graph DB from Django web framework. I'm using Django 1.4.5, neo4j 1.9.2 and neo4django 0.1.8.

As of now Neo4django doesn't support labeling but the above is my core purpose and I want to be able to create labels from Neo4django. So I went into the source code and tried to tweak it a little to see if I can make this addition. In my understanding, the file 'db/models/properties.py' has class BoundProperty(AttrRouter) which calls gremlin script through function save(instance, node, node_is_new). The script is as follows:

script = '''
    node=g.v(nodeId);
    results = Neo4Django.updateNodeProperties(node, propMap);
    '''

The script calls the update function from library.groovy and all the function looks intuitive and nice. I'm trying to add on this function to support labeling but I have no experience of groovy. Does anyone have any suggestions on how to proceed? Any help would be appreciated. If it works it would be a big addition to neo4django :)

Thank you

Answer 1

A little background:

The Groovy code you've highlighted is executed using the Neo4j Gremlin plugin. First it supports the Gremlin graph DSL (eg node=g.v(nodeId)), which is implemented atop the Groovy language. Groovy itself is a dynamic superset of Java, so most valid Java code will work with scripts sent via connection.gremlin(...). Each script sent should define a results variable that will be returned to neo4django, even if it's just null.

Anyway, accessing Neo4j this way is handy (though will be deprecated I've heard :( ) because you can use the full Neo4j embeddeded Java API. Try something like this to add a label to a node

from neo4django.db import connection
connection.gremlin("""
node = g.v(nodeId)
label = DynamicLabel.label('Label_Name')
node.rawVertex.addLabel(label)
""", nodeId=node_id)

You might also need to add an import for DynamicLabel- I haven't run this code so I'm not sure. Debugging code written this way is a little tough, so make liberal use of the Gremlin tab in the Neo4j admin.

If you come up with a working solution, I'd love to see it (or an explanatory blog post!)- I'm sure it could be helpful to other users.

HTH!

NB - Labels will be properly supported shortly after Neo4j 2.0's release- they'll replace the current in-graph type structure.