neo4j query to get a specific formated response

Question

I am having a node network in the neo4j database which includes multilevel nodes something like,

parent -> child -> sub child -> ...and so on

Now what I need is I need to write a query that will give me the response in the below format.

nodes = [
{
    id: parent1,
    children : [{
        id: child1,
        children: [
            {
                id: sub child1,
                children: [... So on]
            },
            {
                id: sub child2,
                children: [... So on]
            }
        ]
    }]
},
{
    id = parent2,
    children : [...so on]
}
]

Answer 1

You can do something like:

MATCH (p:Person)
WHERE size((p)<--()) = 0
CALL apoc.path.expandConfig(p, {
    relationshipFilter: "PARENT>"
})
YIELD path
WITH collect(path) AS paths
CALL apoc.convert.toTree(paths)
YIELD value
RETURN value;

Matching the top parents, which points no one, then using apoc.path.expandConfig to get their paths and then apoc.convert.toTree in order to get the tree-shape structure that you want.

On a sample data:

MERGE (a:Person{key: 1})
MERGE (b:Person{key: 2})
MERGE (c:Person{key: 3})
MERGE (d:Person{key: 4})
MERGE (e:Person{key: 5})
MERGE (f:Person{key: 6})
MERGE (g:Person{key: 7})
MERGE (h:Person{key: 8})
MERGE (i:Person{key: 9})

MERGE (b)-[:PARENT]-(a)
MERGE (d)-[:PARENT]-(c)
MERGE (d)-[:PARENT]-(i)
MERGE (f)-[:PARENT]-(e)
MERGE (g)-[:PARENT]-(b)
MERGE (g)-[:PARENT]-(d)
MERGE (e)-[:PARENT]-(h)

It returns:

[{
  "_type": "Person",
  "parent": [
    {
      "_type": "Person",
      "parent": [
        {
          "_type": "Person",
          "_id": 1444,
          "key": 8
        }
      ],
      "_id": 1441,
      "key": 5
    }
  ],
  "_id": 1442,
  "key": 6
},
{
  "_type": "Person",
  "parent": [
    {
      "_type": "Person",
      "parent": [
        {
          "_type": "Person",
          "_id": 1437,
          "key": 1
        }
      ],
      "_id": 1438,
      "key": 2
    },
    {
      "_type": "Person",
      "parent": [
        {
          "_type": "Person",
          "_id": 1439,
          "key": 3
        },
        {
          "_type": "Person",
          "_id": 1445,
          "key": 9
        }
      ],
      "_id": 1440,
      "key": 4
    }
  ],
  "_id": 1443,
  "key": 7
}]