6.11. Gremlin Plugin

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6.11.1. Send a Gremlin Script - URL encoded
6.11.2. Load a sample graph graph
6.11.3. Sort a result using raw Groovy operations
6.11.4. Send a Gremlin Script - JSON encoded with table result

Gremlin is a Groovy based Graph Traversal Language and 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, have them executed on the server database and return the results as Neo4j Node and Relationship representations, thus keeping the types throughout the REST API consistent. This results is quite verbose listings when returning Neo4j Node, Relationship or Graph representations. On the other hand, just return properties like in the Section 6.11.4, “Send a Gremlin Script - JSON encoded with table result” example for returns tailored to specific needs.

6.11.1. Send a Gremlin Script - URL encoded

Send a Gremlin Script, URL-encoded with UTF-8 encoding, e.g. the equivalent of the Gremlin Script i = g.v(1);i.outE.inV

Example request

POST http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept: application/json
Content-Type: application/x-www-form-urlencoded

script=i+%3D+g.v%282%29%3Bi.outE.inV

Example response

200: OK
Content-Type: application/json

[ {
  "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" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/1/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/1/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/1/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/1/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/1/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/1/clonedSubgraph"
    }
  },
  "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}"
} ]

6.11.2. Load a sample graph graph

Import a graph form a GraphML file can be achieved through the Gremlin GraphMLReader. The following script imports 3 nodes into Neo4j and then returns a list of all nodes in the graph.

Example request

POST http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept: application/json
Content-Type: application/json

{"script":"GraphMLReader.inputGraph(g, new URL('https://raw.github.com/neo4j/gremlin-plugin/master/src/data/graphml1.xml').openStream());g.V"}

Example response

200: OK
Content-Type: application/json

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/0/relationships/out",
  "data" : {
  },
  "traverse" : "http://localhost:7474/db/data/node/0/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/0/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/0/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/0",
  "properties" : "http://localhost:7474/db/data/node/0/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/0/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/0/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/0/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/0/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/0/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/0/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/0/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/0/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/0/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/0/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/0/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/0/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/7/relationships/out",
  "data" : {
    "name" : "I"
  },
  "traverse" : "http://localhost:7474/db/data/node/7/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/7/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/7",
  "properties" : "http://localhost:7474/db/data/node/7/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/7/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/7/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/7/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/7/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/7/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/7/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/7/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/7/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/7/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/7/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/8/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/8/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/8/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/8/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/8",
  "properties" : "http://localhost:7474/db/data/node/8/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/8/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/8/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/8/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/8/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/8/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/8/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/8/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/8/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/8/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/8/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/8/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/8/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/9/relationships/out",
  "data" : {
    "name" : "him"
  },
  "traverse" : "http://localhost:7474/db/data/node/9/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/9/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/9/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/9",
  "properties" : "http://localhost:7474/db/data/node/9/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/9/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/9/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/9/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/9/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/9/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/9/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/9/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/9/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/9/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/9/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/9/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/9/relationships/in/{-list|&|types}"
} ]

6.11.3. Sort a result using raw Groovy operations

The following script returns a sorted list of all nodes connected via outgoing relationships to node 1, sorted by their name-property.

Example request

POST http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept: application/json
Content-Type: application/json

{"script":"g.v(12).outE.inV.sort{it.name}.toList()"}

Example response

200: OK
Content-Type: application/json

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/11/relationships/out",
  "data" : {
    "name" : "him"
  },
  "traverse" : "http://localhost:7474/db/data/node/11/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/11/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/11",
  "properties" : "http://localhost:7474/db/data/node/11/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/11/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/11/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/11/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/11/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/11/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/11/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/11/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/11/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/11/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/11/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/10/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/10/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/10/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/10/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/10",
  "properties" : "http://localhost:7474/db/data/node/10/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/10/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/10/relationships/in",
  "extensions" : {
    "FunctionalTestPlugin" : {
      "connected_nodes" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/10/connected_nodes",
      "pathToReference" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/10/pathToReference",
      "getThisNodeOrById" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/10/getThisNodeOrById",
      "createRelationships" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/10/createRelationships",
      "getRelationshipsBetween" : "http://localhost:7474/db/data/ext/FunctionalTestPlugin/node/10/getRelationshipsBetween"
    },
    "GraphCloner" : {
      "clonedSubgraph" : "http://localhost:7474/db/data/ext/GraphCloner/node/10/clonedSubgraph"
    }
  },
  "create_relationship" : "http://localhost:7474/db/data/node/10/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/10/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/10/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/10/relationships/in/{-list|&|types}"
} ]

6.11.4. Send a Gremlin Script - JSON encoded with table result

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 >> -1.

Example request

POST http://localhost:7474/db/data/ext/GremlinPlugin/graphdb/execute_script
Accept: application/json
Content-Type: application/json

{"script":"i = g.v(15);t= new Table();i.as('I').out('know').as('friend').out('like').as('likes').table(t,['friend','likes']){it.name}{it.name} >> -1;t;"}

Example response

200: OK
Content-Type: application/json

{
  "data" : [ [ "Joe", "cats" ], [ "Joe", "dogs" ] ],
  "columns" : [ "friend", "likes" ]
}