Gremlin is a Groovy based Graph Traversal Language. It provides a very expressive way of explicitly scripting traversals through a Neo4j graph.
The Neo4j Gremlin Plugin provides an endpoint to send Gremlin scripts to the Neo4j Server.
The scripts are executed on the server database and the results are returned as Neo4j Node and Relationship representations.
This keeps the types throughout the REST API consistent.
The results are quite verbose when returning Neo4j Node
,
Relationship
or Graph
representations.
On the other hand, just return properties like in the Section 22.18.4, “Send a Gremlin Script - JSON encoded with table results”
example for responses tailored to specific needs.
Warning | |
---|---|
The Gremlin plugin lets you execute arbitrary Groovy code under the hood. In hosted and open environments, this can constitute a security risk. In these case, consider using declarative approaches like Part III, “Cypher Query Language” or write your own server side plugin executing the interesting Gremlin or Java routines, see Section 9.1, “Server Plugins” or secure your server, see Section 28.1, “Securing access to the Neo4j Server”. |
Tip | |
---|---|
When returning results from pipes like |
Scripts can be sent as URL-encoded In this example, the graph has been autoindexed by Neo4j, so we can look up the name property on nodes.
Raw script source
g.idx('node_auto_index')[[name:'I']].out
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/x-www-form-urlencoded
script=g.idx%28%27node_auto_index%27%29%5B%5Bname%3A%27I%27%5D%5D.out
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/13/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/13/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/13/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/13/properties/{key}", "self" : "http://localhost:7474/db/data/node/13", "properties" : "http://localhost:7474/db/data/node/13/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/13/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/13/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/13/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/13/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/13/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/13/relationships/in/{-list|&|types}" } ]
Importing a graph from a GraphML file can be achieved through the Gremlin GraphMLReader. The following script imports a small GraphML file from an URL into Neo4j, resulting in the depicted graph. The underlying database is auto-indexed, see Section 19.12, “Automatic Indexing” so the script can return the imported node by index lookup.
Raw script source
g.clear() g.loadGraphML('file:/var/neodata/ci/jenkins/workspace/release-candidate-1.9/target/gremlin-plugin/target/test-classes/graphml.xml') g.idx('node_auto_index')[[name:'you']]
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.clear();g.loadGraphML('file:/var/neodata/ci/jenkins/workspace/release-candidate-1.9/target/gremlin-plugin/target/test-classes/graphml.xml');g.idx('node_auto_index')[[name:'you']];", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/45/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/45/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/45/properties/{key}", "self" : "http://localhost:7474/db/data/node/45", "properties" : "http://localhost:7474/db/data/node/45/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/45/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/45/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/45/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/45/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/in/{-list|&|types}" } ]
The following script returns a sorted list of all nodes connected via
outgoing relationships to node 1, sorted by their name
-property.
Raw script source
g.idx('node_auto_index')[[name:'I']].out.sort{it.name}
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.idx('node_auto_index')[[name:'I']].out.sort{it.name}", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/66/relationships/out", "data" : { "name" : "him" }, "traverse" : "http://localhost:7474/db/data/node/66/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/66/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/66/properties/{key}", "self" : "http://localhost:7474/db/data/node/66", "properties" : "http://localhost:7474/db/data/node/66/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/66/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/66/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/66/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/66/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/66/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/66/relationships/in/{-list|&|types}" }, { "outgoing_relationships" : "http://localhost:7474/db/data/node/65/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/65/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/65/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/65/properties/{key}", "self" : "http://localhost:7474/db/data/node/65", "properties" : "http://localhost:7474/db/data/node/65/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/65/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/65/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/65/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/65/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/65/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/65/relationships/in/{-list|&|types}" } ]
To send a Script JSON encoded, set the payload Content-Type Header. In
this example, find all the things that my friends like, and return a
table listing my friends by their name, and the names of the things they
like in a table with two columns, ignoring the third named step variable
I
. Remember that everything in Gremlin is an iterator - in order to
populate the result table t
, iterate through the pipes with
iterate()
.
Raw script source
t= new Table() g.v(49).as('I').out('know').as('friend').out('like').as('likes').table(t,['friend','likes']){it.name}{it.name}.iterate() t
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "t= new Table();g.v(49).as('I').out('know').as('friend').out('like').as('likes').table(t,['friend','likes']){it.name}{it.name}.iterate();t;", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
{ "columns" : [ "friend", "likes" ], "data" : [ [ "Joe", "cats" ], [ "Joe", "dogs" ] ] }
Raw script source
g.v(23).as('I').out('know').as('friend').out('like').as('likes').table(new Table()){it.name}{it.name}.cap
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(23).as('I').out('know').as('friend').out('like').as('likes').table(new Table()){it.name}{it.name}.cap;", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "data" : [ [ "I", "Joe", "cats" ], [ "I", "Joe", "dogs" ] ], "columns" : [ "I", "friend", "likes" ] } ]
To set variables in the bindings for the Gremlin Script Engine on the
server, you can include a params
parameter with a String representing a
JSON map of variables to set to initial values. These can then be
accessed as normal variables within the script.
Raw script source
meaning_of_life
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "meaning_of_life", "params" : { "meaning_of_life" : 42.0 } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
42.0
Send a Gremlin Script, as JSON payload and additional parameters
Raw script source
g.v(me).out
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(me).out", "params" : { "me" : "32" } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/31/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/31/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/31/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/31/properties/{key}", "self" : "http://localhost:7474/db/data/node/31", "properties" : "http://localhost:7474/db/data/node/31/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/31/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/31/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/31/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/31/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/31/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/31/relationships/in/{-list|&|types}" } ]
The following script returns paths. Paths in Gremlin consist of the pipes that make up the path from the starting pipes. The server is returning JSON representations of their content as a nested list.
Raw script source
g.v(3).out.name.paths
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(3).out.name.paths", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ [ { "outgoing_relationships" : "http://localhost:7474/db/data/node/3/relationships/out", "data" : { "name" : "I" }, "traverse" : "http://localhost:7474/db/data/node/3/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/3/properties/{key}", "self" : "http://localhost:7474/db/data/node/3", "properties" : "http://localhost:7474/db/data/node/3/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/3/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/3/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/3/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/3/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/in/{-list|&|types}" }, { "outgoing_relationships" : "http://localhost:7474/db/data/node/1/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/1/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/1/properties/{key}", "self" : "http://localhost:7474/db/data/node/1", "properties" : "http://localhost:7474/db/data/node/1/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/1/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/1/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/1/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/1/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/in/{-list|&|types}" }, "you" ], [ { "outgoing_relationships" : "http://localhost:7474/db/data/node/3/relationships/out", "data" : { "name" : "I" }, "traverse" : "http://localhost:7474/db/data/node/3/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/3/properties/{key}", "self" : "http://localhost:7474/db/data/node/3", "properties" : "http://localhost:7474/db/data/node/3/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/3/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/3/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/3/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/3/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/in/{-list|&|types}" }, { "outgoing_relationships" : "http://localhost:7474/db/data/node/2/relationships/out", "data" : { "name" : "him" }, "traverse" : "http://localhost:7474/db/data/node/2/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/2/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/2/properties/{key}", "self" : "http://localhost:7474/db/data/node/2", "properties" : "http://localhost:7474/db/data/node/2/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/2/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/2/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/2/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/2/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/2/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/2/relationships/in/{-list|&|types}" }, "him" ] ]
This example demonstrates that you via the Groovy runtime embedded with the server have full access to all of the servers Java APIs. The below example creates Nodes in the database both via the Blueprints and the Neo4j API indexes the nodes via the native Neo4j Indexing API constructs a custom Lucene sorting and searching returns a Neo4j IndexHits result iterator.
Raw script source
'******** Additional imports *********' import org.neo4j.graphdb.index.* import org.neo4j.graphdb.* import org.neo4j.index.lucene.* import org.apache.lucene.search.* '**** Blueprints API methods on the injected Neo4jGraph at variable g ****' meVertex = g.addVertex([name:'me']) meNode = meVertex.getRawVertex() '*** get the Neo4j raw instance ***' neo4j = g.getRawGraph() '******** Neo4j API methods: *********' tx = neo4j.beginTx() youNode = neo4j.createNode() youNode.setProperty('name','you') youNode.createRelationshipTo(meNode,DynamicRelationshipType.withName('knows')) '*** index using Neo4j APIs ***' idxManager = neo4j.index() personIndex = idxManager.forNodes('persons') personIndex.add(meNode,'name',meNode.getProperty('name')) personIndex.add(youNode,'name',youNode.getProperty('name')) tx.success() tx.finish() '*** Prepare a custom Lucene query context with Neo4j API ***' query = new QueryContext( 'name:*' ).sort( new Sort(new SortField( 'name',SortField.STRING, true ) ) ) results = personIndex.query( query )
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "'******** Additional imports *********';import org.neo4j.graphdb.index.*;import org.neo4j.graphdb.*;import org.neo4j.index.lucene.*;import org.apache.lucene.search.*;;'**** Blueprints API methods on the injected Neo4jGraph at variable g ****';meVertex = g.addVertex([name:'me']);meNode = meVertex.getRawVertex();;'*** get the Neo4j raw instance ***';neo4j = g.getRawGraph();;;'******** Neo4j API methods: *********';tx = neo4j.beginTx(); youNode = neo4j.createNode(); youNode.setProperty('name','you'); youNode.createRelationshipTo(meNode,DynamicRelationshipType.withName('knows'));;'*** index using Neo4j APIs ***'; idxManager = neo4j.index(); personIndex = idxManager.forNodes('persons'); personIndex.add(meNode,'name',meNode.getProperty('name')); personIndex.add(youNode,'name',youNode.getProperty('name'));tx.success();tx.finish();;;'*** Prepare a custom Lucene query context with Neo4j API ***';query = new QueryContext( 'name:*' ).sort( new Sort(new SortField( 'name',SortField.STRING, true ) ) );results = personIndex.query( query );", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/20/relationships/out", "data" : { "name" : "you" }, "traverse" : "http://localhost:7474/db/data/node/20/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/20/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/20/properties/{key}", "self" : "http://localhost:7474/db/data/node/20", "properties" : "http://localhost:7474/db/data/node/20/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/20/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/20/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/20/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/20/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/20/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/20/relationships/in/{-list|&|types}" }, { "outgoing_relationships" : "http://localhost:7474/db/data/node/19/relationships/out", "data" : { "name" : "me" }, "traverse" : "http://localhost:7474/db/data/node/19/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/19/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/19/properties/{key}", "self" : "http://localhost:7474/db/data/node/19", "properties" : "http://localhost:7474/db/data/node/19/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/19/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/19/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/19/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/19/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/19/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/19/relationships/in/{-list|&|types}" } ]
Exporting a graph can be done by simple emitting the appropriate String.
Raw script source
writer = new GraphMLWriter(g) out = new java.io.ByteArrayOutputStream() writer.outputGraph(out) result = out.toString()
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "writer = new GraphMLWriter(g);out = new java.io.ByteArrayOutputStream();writer.outputGraph(out);result = out.toString();", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
"<?xml version=\"1.0\" ?><graphml xmlns=\"http://graphml.graphdrawing.org/xmlns\"><key id=\"name\" for=\"node\" attr.name=\"name\" attr.type=\"string\"></key><graph id=\"G\" edgedefault=\"directed\"><node id=\"53\"><data key=\"name\">you</data></node><node id=\"54\"><data key=\"name\">him</data></node><node id=\"55\"><data key=\"name\">I</data></node><edge id=\"46\" source=\"55\" target=\"53\" label=\"know\"></edge><edge id=\"47\" source=\"55\" target=\"54\" label=\"know\"></edge></graph></graphml>"
Imagine a user being part of different groups. A group can have different
roles, and a user can be part of different groups. He also can have
different roles in different groups apart from the membership. The
association of a User, a Group and a Role can be referred to as a
HyperEdge. However, it can be easily modeled in a property graph as a
node that captures this n-ary relationship, as depicted below in the
U1G2R1
node.
To find out in what roles a user is for a particular groups (here Group2), the following script can traverse this HyperEdge node and provide answers.
Raw script source
g.v(39).out('hasRoleInGroup').as('hyperedge').out('hasGroup').filter{it.name=='Group2'}.back('hyperedge').out('hasRole').name
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(39).out('hasRoleInGroup').as('hyperedge').out('hasGroup').filter{it.name=='Group2'}.back('hyperedge').out('hasRole').name", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ "Role1" ]
This example is showing a group count in Gremlin, for instance the counting of the different relationship types connected to some the start node. The result is collected into a variable that then is returned.
Raw script source
m = [:] g.v(60).bothE().label.groupCount(m).iterate() m
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "m = [:];g.v(60).bothE().label.groupCount(m).iterate();m", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
{ "knows" : 2, "likes" : 1 }
Multiple traversals can be combined into a single result, using splitting and merging pipes in a lazy fashion.
Raw script source
g.idx('node_auto_index')[[name:'Peter']].copySplit(_().out('knows'), _().in('likes')).fairMerge.name
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.idx('node_auto_index')[[name:'Peter']].copySplit(_().out('knows'), _().in('likes')).fairMerge.name", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ "Ian", "Marie" ]
This example demonstrates basic collaborative filtering - ordering a traversal after occurence counts and substracting objects that are not interesting in the final result.
Here, we are finding Friends-of-Friends that are not Joes friends
already. The same can be applied to graphs of users that LIKE
things
and others.
Raw script source
x=[] fof=[:] g.v(12).out('knows').aggregate(x).out('knows').except(x).groupCount(fof).iterate() fof.sort{a,b -> b.value <=> a.value}
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "x=[];fof=[:];g.v(12).out('knows').aggregate(x).out('knows').except(x).groupCount(fof).iterate();fof.sort{a,b -> b.value <=> a.value}", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
{ "v[10]" : 2, "v[9]" : 1, "v[11]" : 1 }
Raw script source
g.v(30).out('knows').filter{it.name == 'Sara'}[0..100]
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(30).out('knows').filter{it.name == 'Sara'}[0..100]", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ { "outgoing_relationships" : "http://localhost:7474/db/data/node/28/relationships/out", "data" : { "name" : "Sara" }, "traverse" : "http://localhost:7474/db/data/node/28/traverse/{returnType}", "all_typed_relationships" : "http://localhost:7474/db/data/node/28/relationships/all/{-list|&|types}", "property" : "http://localhost:7474/db/data/node/28/properties/{key}", "self" : "http://localhost:7474/db/data/node/28", "properties" : "http://localhost:7474/db/data/node/28/properties", "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/28/relationships/out/{-list|&|types}", "incoming_relationships" : "http://localhost:7474/db/data/node/28/relationships/in", "extensions" : { }, "create_relationship" : "http://localhost:7474/db/data/node/28/relationships", "paged_traverse" : "http://localhost:7474/db/data/node/28/paged/traverse/{returnType}{?pageSize,leaseTime}", "all_relationships" : "http://localhost:7474/db/data/node/28/relationships/all", "incoming_typed_relationships" : "http://localhost:7474/db/data/node/28/relationships/in/{-list|&|types}" } ]
In this case, the Peter node is disconnected from all other nodes.
Raw script source
g.v(77).bothE.each{g.removeEdge(it)}
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.v(77).bothE.each{g.removeEdge(it)}", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
[ ]
This is a basic stub example for implementing flow algorithms in for
instance Flow Networks with a
pipes-based approach and scripting, here between source
and sink
using the capacity
property on relationships as the base for the flow
function and modifying the graph during calculation.
Raw script source
source=g.v(79) sink=g.v(80) maxFlow = 0 source.outE.inV.loop(2){!it.object.equals(sink)}.paths.each{flow = it.capacity.min() maxFlow += flow it.findAll{it.capacity}.each{it.capacity -= flow}} maxFlow
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "source=g.v(79);sink=g.v(80);maxFlow = 0;source.outE.inV.loop(2){!it.object.equals(sink)}.paths.each{flow = it.capacity.min(); maxFlow += flow;it.findAll{it.capacity}.each{it.capacity -= flow}};maxFlow", "params" : { } }
Example response
200:
OK
Content-Type:
application/json; charset=UTF-8
4
Script errors will result in an HTTP error response code.
Example request
POST
http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept:
application/json; charset=UTF-8
Content-Type:
application/json
{ "script" : "g.addVertex([name:{}])" }
Example response
400:
Bad Request
Content-Type:
application/json; charset=UTF-8
{ "message": "javax.script.ScriptException: java.lang.IllegalArgumentException: Unknown property type on: Script9$_run_closure1@ef9e8eb, class Script9$_run_closure1", "exception": "BadInputException", "fullname": "org.neo4j.server.rest.repr.BadInputException", "stacktrace": [ "org.neo4j.server.plugin.gremlin.GremlinPlugin.executeScript(GremlinPlugin.java:84)", "java.lang.reflect.Method.invoke(Method.java:597)", "org.neo4j.server.plugins.PluginMethod.invoke(PluginMethod.java:57)", "org.neo4j.server.plugins.PluginManager.invoke(PluginManager.java:168)", "org.neo4j.server.rest.web.ExtensionService.invokeGraphDatabaseExtension(ExtensionService.java:300)", "org.neo4j.server.rest.web.ExtensionService.invokeGraphDatabaseExtension(ExtensionService.java:122)", "java.lang.reflect.Method.invoke(Method.java:597)", "org.neo4j.server.rest.security.SecurityFilter.doFilter(SecurityFilter.java:112)" ] }
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