CODEWITHSUNDEEP
azure-cosmosdbgremlin
Murilo Maciel Curti
Murilo Maciel Curti

Reputation: 3141

Azure Cosmos Graph How to select vertex properties to return?

if I have a vertex like this:

{
  "id": "1",
  "label": "user",
  "type": "vertex",
  "outE": {
    "worksAt": [
      {
        "id": "6e47aa14-0a3a-4e45-8ac4-043ec9f32b50",
        "inV": "spaceneedle.com.br"
      }
    ]
  },
  "properties": {
    "name": [
      {
        "id": "cce42090-efc5-4bb2-9576-922d19164d98",
        "value": "Murilo"
      }
    ],
    "domain": [
      {
        "id": "murilo|domain",
        "value": "spaceneedle.com.br"
      }
    ]
  }
}

Is it possible to choose properties to return to have an object like the following using gremlin?

{
  "id": "1",
  "name": "Murilo"
}

Thanks!

Upvotes: 2

Views: 811

Answers (1)

stephen mallette
stephen mallette

Reputation: 46226

I'll use the TinkerPop "modern" toy graph to demonstrate some options:

gremlin> graph = TinkerFactory.createModern()
==>tinkergraph[vertices:6 edges:6]
gremlin> g = graph.traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]

You could do something like this:

gremlin> g.V(1).valueMap(true,'name')
==>[label:person,name:[marko],id:1]

but that includes vertex label and wraps the "name" in a list (to account for multi-properties). So, while quick/easy, it's not quite a match for the output you asked for. To get that specific output, I would use project() step which would look like this:

gremlin> g.V(1).project("id","name").by(id).by('name')
==>[id:1,name:marko]

If you have a mix of vertices that are being projected where some may not have certain properties you can use coalesce() or similar means to ensure a default value:

gremlin> g.V().project('id','name','age').by(id).by('name').by(coalesce(values('age'),constant('none')))
==>[id:1,name:marko,age:45]
==>[id:2,name:vadas,age:27]
==>[id:3,name:lop,age:none]
==>[id:4,name:josh,age:32]
==>[id:5,name:ripple,age:none]
==>[id:6,name:peter,age:35]

Upvotes: 4

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