Traversal with multiple seed nodes

Question

I wrote a quick script that runs a traversal query through Neo4j's traversal framework REST API:

from py2neo import neo4j
import requests
import json

dbURI = 'http://localhost:7474/db/data/'

def graphTraversal (nodeId):
    returnType = 'path'

    payload = {
        'order': 'breadth_first',
        'uniqueness': 'node_global',
        'relationships': [{
            'direction': 'all',
            'type': 'associatedMusicalArtist' 
        }],
        'max_depth': 2
    }
    payload = json.dumps(payload)

    headers = {
        'Accept': 'application/json; charset=UTF-8',
        'Content-Type': 'application/json'
    }

    uri = dbURI + '/node/' + nodeId + '/traverse/' + returnType
    print '\n> Traversal of ' + uri + ' ...'
    res = requests.post(uri, data=payload, headers=headers)
    print res.text
    return res.json();

def getNodeByUri (db, key, value):
    return db.get_indexed_node('nodeIdx', key, value)

def getNodeId (node):
    return str(node._id)

def main ():
    db = neo4j.GraphDatabaseService(dbURI)

    node = getNodeByUri(db, '__URI__', 'http://dbpedia.org/resource/Jimi_Hendrix')
    nodeId = getNodeId(node)

    rels = graphTraversal(nodeId)

if __name__ == '__main__':
    main()

The code runs fine, but I have a question:

• How can I run this same traversal but with multiple seed / root nodes ?

I know that the Java driver permits this but for Python, the documentation isn't clear about how to do it.

Thanks in advance!

EDIT: Here's a link to the documentation of Neo4j's traversal framework REST API I'm following.

Answer 1

There is no direct way to do this, the traversal endpoints are all single-node.

You can do it by using the Batch API, sending lots of traversal requests in a single HTTP request. Have a look here:

http://docs.neo4j.org/chunked/stable/rest-api-batch-ops.html

However

For the Traversal you are running, you could easily express it in Cypher, and then you'd be able to give it multiple start points, like so:

START n=node(1,2,3,4,5) MATCH (n)-[:associatedMusicalArtist*0..2]-(other) RETURN other

Which you can then send to the the transactional endpoint:

http://docs.neo4j.org/chunked/stable/rest-api-transactional.html