from Neo4j to GraphJSON with Ruby -


i'm trying visualizations using d3.js or alchemy.js--but alchemy, in particular, requires datasource in graphjson.

i've been playing around tutorials , examples of max de marzi (using neography), michael hunger (cy2neo, js), neo4j, , neo4j.rb -- cannot seem way there. because don't know i'm doing--but how i'm trying learn.

what i'm trying achieve along lines of: https://bl.ocks.org/mbostock/3750558 or default visualization here: http://graphalchemist.github.io/alchemy/#/docs

and can see graphjson formatting should finding on page also: http://graphalchemist.github.io/alchemy/#/docs

if run following...

get '/followers'   neo4j::session.open(:server_db, "http://localhost:7474")   query = neo4j::session.query('match (a--(b)--(c) return a,b,c limit 30')   puts "--------------"   puts query_to_graph_json(query)    query_to_graph_json(query)  end  # supposed grab nodes , edges, never gets edges. # it's conversation @ neo4j.rb site     def query_to_graph_json(query)     nodes = {}     edges = {}      add_datum = proc.new |datum|       case datum       when neo4j::activenode, neo4j::server::cyphernode         nodes[datum.neo_id] = {         id: datum.neo_id,         properties: datum.props #was attributes, kept saying wasn't method         }       when neo4j::activerel, neo4j::server::cypherrelationship         edges[[datum.start_node.neo_id, datum.end_node.neo_id]] = {         source: datum.start_node.neo_id,         target: datum.end_node.neo_id,         type: datum.rel_type,         properties: datum.props         }       else         raise "invalid value found: #{datum.inspect}"       end     end      query.each |row|       row.to_a.each |datum|         if datum.is_a?(array)           datum.each {|d| add_datum.call(d) }         else           add_datum.call(datum)         end       end     end      {       nodes: nodes.values,       edges: edges.values     }.to_json   end

i'll get...

{   "nodes": [     {       "id": 597,       "properties": {         "name": "john",         "type": "person"       }     },     {       "id": 127,       "properties": {         "name": "chris",         "type": "person"       }     },     {       "id": 129,       "properties": {         "name": "suzie",         "type": "person"       }     }, ],   "edges": [    ] }

the problem being need edges.

if run...

get '/followers'   content_type :json   neo = neography::rest.new("http://localhost:7474")   cypher = "match (a)--(b)--(c) return id(a),a.name,id(b),b.name,id(c),c.name limit 30"   puts neo.execute_query(cypher).to_json end

i'll table of paths. it's not formatted in way need--and have no idea how might format graphjson format.

{   "columns": [     "id(a)",     "a.name",     "id(b)",     "b.name",     "id(c)",     "c.name"   ],   "data": [     [       597,       "john",       127,       "chris",       129,       "suzie"     ],     [       597,       "john",       6,       "adam",       595,       "pee-wee"     ]   ] }

i think 1 problem you're having that, instead of matching 2 nodes , 1 relationship, you're matching 3 nodes , 2 relationships. here's match:

match (a)--(b)--(c)

it should like:

match (a)-[b]-(c)

in match clause [] can excluded , can raw -- (or --> or <--) represents relationship.

you want querying 1 specific direction though. if query bidirectionally you'll same relationship twice start , end nodes switched.

using neo4j-core (which biased towards 1 of maintainers ;)

nodes = [] rels = [] session.query('(source)-[rel]->(target)').pluck(:source, :rel, :target).each |source, rel, target|   nodes << source   nodes << target   rels << rel end  {   nodes: nodes,   edges: rels }.to_json

also note if don't specify labels query might slow, depending on number of nodes). depends on need ;)


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