Search code examples
graph-databasesgremlintinkerpopamazon-neptune

Query returning wrong values

I'm testing and studying Neptune with Gremlin. I have created a few nodes of type User that simply have an id and an email. If I make a raw query for them I get:

// http://my-neptune/?gremlin=g.V().hasLabel('User')

  "result": {
    "data": {
      "@type": "g:List",
      "@value": [
        {
          "@type": "g:Vertex",
          "@value": {
            "id": "u01",
            "label": "User",
            "properties": {
              "email": [
                {
                  "@type": "g:VertexProperty",
                  "@value": {
                    "id": {
                      "@type": "g:Int32",
                      "@value": 2051025270
                    },
                    "value": "User01@email.com",
                    "label": "email"
                  }
                }
              ]
            }
          }
        },
        {
          "@type": "g:Vertex",
          "@value": {
            "id": "u02",
            "label": "User",
            "properties": {
              "email": [
                {
                  "@type": "g:VertexProperty",
                  "@value": {
                    "id": {
                      "@type": "g:Int32",
                      "@value": -374298315
                    },
                    "value": "user02@mail.com",
                    "label": "email"
                  }
                }
              ]
            }
          }
        }
      ]
    }

I wan't to represent this graph using visjs. So I would like to return basically 3 properties for each node:

  • ID
  • Label (which is shown in the node, and I would like a format like id - mail)
  • Group (to group the nodes by color and shape)

To do so, I'm executing the following query:

g.V()
    .hasLabel('User')
    .project('id', 'label', 'group')
    .by(T.id)
    .by(
        union(id(), values('email'))
        .fold()
    )
    .by(T.label)

But the result is not as expected. I get the projection for label right only for the first node and empty for the others:

  "result": {
    "data": {
      "@type": "g:List",
      "@value": [
        {
          "@type": "g:Map",
          "@value": [
            "id",
            "u01",
            "label",
            {
              "@type": "g:List",
              "@value": [
                "u01",
                "User01@email.com"
              ]
            },
            "group",
            "User"
          ]
        },
        {
          "@type": "g:Map",
          "@value": [
            "id",
            "u02",
            "group",
            "User",
            "label",
            {
              "@type": "g:List",
              "@value": [
                // This list should not be empty 
              ]
            }
          ]
        }
      ]
    }

Any ideas why this happens or how could I execute a similar task?

Solution

  • Adding an answer so that the solution proposed in the comments can be accepted if the new version mentioned did resolve the issue.

    Upgrading the Neptune instance to https://docs.aws.amazon.com/neptune/latest/userguide/engine-releases-1.0.2.1.R4.html should resolve the issue.