How to access nested json in vega

I am using vega in kibana. I try to access nested json field but I cannot able to access that field, could anyone help me to resolve this issue. I attach my vega json and index name is pie

index data sample:

{ “_index”: “pie”, “_type”: “flare”, “_id”: “2”, “_version”: 1, “_score”: 1, “_source”: { “id”: 2, “parent”: 1, “data” :{ “memory”: 50 } } }

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Your question was successfully posted! avatar image How to access nested json in vega Question by Narasimma varman 21 secs ago elasticsearchkibanalogstash

I am using vega in kibana. I try to access nested json field but I cannot able to access that field, could anyone help me to resolve this issue. I attach my vega json and index name is pie

index data sample:

{ “_index”: “pie”, “_type”: “flare”, “_id”: “2”, “_version”: 1, “_score”: 1, “_source”: { “id”: 2, “parent”: 1, “data” :{ “memory”: 50 } } }

{
"$schema": "https://vega.github.io/schema/vega/v3.json",
"data": [
{
"name": "table",
"url": {
 
"%context%": "true",
 
 "index": "pie*",
 
 "body": {
 
  "size": "10"
 
 
 }
 },
 
"format": { "property": "hits.hits" },
 
"transform": [
 {
  "type": "formula",
  "expr": "toNumber(datum[\"_source\"][\"data\"][\"memory\"])",
  "as": "memory"
    }
      ],
 "transform": [{"type": "pie", "field": "memory"}]
 }  ],
 
  "scales": [
   {
 "name": "r",
  "type": "sqrt",
  "domain": {"data": "table", "field": "memory"},
 "zero": true,
 "range": [20, 100]
     }
   ],
 
 "marks": [
{
 "type": "arc",
  "from": {"data": "table"},
  "encode": {
   "enter": {
    "x": {"field": {"group": "width"}, "mult": 0.5},
  "y": {"field": {"group": "height"}, "mult": 0.5},
  "startAngle": {"field": "startAngle"},
  "endAngle": {"field": "endAngle"},
  "innerRadius": {"value": 20},
  "outerRadius": {"scale": "r", "field": "memory"},
  "stroke": {"value": "#fff"}
},
"update": {
  "fill": {"value": "#ccc"}
},
"hover": {
  "fill": {"value": "skyblue"}
}
  }
   },
 
{
 "type": "text",
 "from": {"data": "table"},
"encode": {
"enter": {
  "x": {"field": {"group": "width"}, "mult": 0.5},
  "y": {"field": {"group": "height"}, "mult": 0.5},
  "radius": {"scale": "r", "field": "memory", "offset": 8},
  "theta": {"signal": "(datum.startAngle + datum.endAngle)/2"},
  "fill": {"value": "#000"},
  "align": {"value": "center"},
  "baseline": {"value": "middle"},
  "text": {"field": "memory"}
 }
}
}
]     
  }`

[mattijn]

You’ve defined a "format": { "property": "hits.hits" } in your data variable, which I don’t see in your data. Even if it was, in my understanding property doesn’t accept double nested parameters (eg. varx.vary), but for that I might be wrong.

Next you have two transform definitions in a single data specification.

Changing this, gives me:

Click to expand

{
  "$schema": "https://vega.github.io/schema/vega/v4.json",
  "data": [
    {
      "name": "table",
      "values": [
        {
          "_index": "pie",
          "_type": "flare",
          "_id": "2",
          "_version": 1,
          "_score": 1,
          "_source": {"id": 2, "parent": 1, "data": {"memory": 50}}
        }
      ],
      "transform": [
        {
          "type": "formula",
          "expr": "toNumber(datum[\"_source\"][\"data\"][\"memory\"])",
          "as": "memory"
        },
        {"type": "pie", "field": "memory"}
      ]
    }
  ],
  "scales": [
    {
      "name": "r",
      "type": "sqrt",
      "domain": {"data": "table", "field": "memory"},
      "zero": true,
      "range": [20, 100]
    }
  ],
  "marks": [
    {
      "type": "arc",
      "from": {"data": "table"},
      "encode": {
        "enter": {
          "x": {"field": {"group": "width"}, "mult": 0.5},
          "y": {"field": {"group": "height"}, "mult": 0.5},
          "startAngle": {"field": "startAngle"},
          "endAngle": {"field": "endAngle"},
          "innerRadius": {"value": 20},
          "outerRadius": {"scale": "r", "field": "memory"},
          "stroke": {"value": "#fff"}
        },
        "update": {"fill": {"value": "#ccc"}},
        "hover": {"fill": {"value": "skyblue"}}
      }
    },
    {
      "type": "text",
      "from": {"data": "table"},
      "encode": {
        "enter": {
          "x": {"field": {"group": "width"}, "mult": 0.5},
          "y": {"field": {"group": "height"}, "mult": 0.5},
          "radius": {"scale": "r", "field": "memory", "offset": 8},
          "theta": {"signal": "(datum.startAngle + datum.endAngle)/2"},
          "fill": {"value": "#000"},
          "align": {"value": "center"},
          "baseline": {"value": "middle"},
          "text": {"field": "memory"}
        }
      }
    }
  ]
}

[mattijn]

You could use flatten(docs), which maps array-valued fields to a set of individual data objects. In combination with project (docs), it is possible to place nested fields on a higher level towards.

"transform": [
  {
    "type": "flatten",
    "fields": ["_source.data"],
    "as": ["data"]
  },
  {
    "type": "project",
    "fields": ["data.memory.value"],
    "as": ["memory"]
  },
  {"type": "pie", "field": "memory"}       
]