neo4j - Using Cypher to return nested, hierarchical JSON from a tree

Question

I'm currently using the example data on console.neo4j.org to write a query that outputs hierarchical JSON.

The example data is created with

create (Neo:Crew {name:'Neo'}), (Morpheus:Crew {name: 'Morpheus'}), (Trinity:Crew {name: 'Trinity'}), (Cypher:Crew:Matrix {name: 'Cypher'}), (Smith:Matrix {name: 'Agent Smith'}), (Architect:Matrix {name:'The Architect'}),
(Neo)-[:KNOWS]->(Morpheus), (Neo)-[:LOVES]->(Trinity), (Morpheus)-[:KNOWS]->(Trinity),
(Morpheus)-[:KNOWS]->(Cypher), (Cypher)-[:KNOWS]->(Smith), (Smith)-[:CODED_BY]->(Architect)

The ideal output is as follows

name:"Neo"
children: [
  { 
    name: "Morpheus",
    children: [
      {name: "Trinity", children: []}
      {name: "Cypher", children: [
        {name: "Agent Smith", children: []}
      ]}
    ]
  }
]
}

Right now, I'm using the following query

MATCH p =(:Crew { name: "Neo" })-[q:KNOWS*0..]-m
RETURN extract(n IN nodes(p)| n)

and getting this

[(0:Crew {name:"Neo"})]
[(0:Crew {name:"Neo"}), (1:Crew {name:"Morpheus"})]
[(0:Crew {name:"Neo"}), (1:Crew {name:"Morpheus"}), (2:Crew {name:"Trinity"})]
[(0:Crew {name:"Neo"}), (1:Crew {name:"Morpheus"}), (3:Crew:Matrix {name:"Cypher"})]
[(0:Crew {name:"Neo"}), (1:Crew {name:"Morpheus"}), (3:Crew:Matrix {name:"Cypher"}), (4:Matrix {name:"Agent Smith"})]

Any tips to figure this out? Thanks

Answer 1

In neo4j 3.x, after you install the APOC plugin on the neo4j server, you can call the apoc.convert.toTree procedure to generate similar results.

For example:

MATCH p=(n:Crew {name:'Neo'})-[:KNOWS*]->(m)
WITH COLLECT(p) AS ps
CALL apoc.convert.toTree(ps) yield value
RETURN value;

... would return a result row that looks like this:

    {
      "_id": 127,
      "_type": "Crew",
      "name": "Neo",
      "knows": [
        {
          "_id": 128,
          "_type": "Crew",
          "name": "Morpheus",
          "knows": [
            {
              "_id": 129,
              "_type": "Crew",
              "name": "Trinity"
            },
            {
              "_id": 130,
              "_type": "Crew:Matrix",
              "name": "Cypher",
              "knows": [
                {
                  "_id": 131,
                  "_type": "Matrix",
                  "name": "Agent Smith"
                }
              ]
            }
          ]
        }
      ]
    }