Query result brings expected data but I get the error "Cannot read property '...' of undefined"

I started to encounter the "Cannot read property '...' of undefined" error for the following document fields:

  • operators: is an array of objects and I expected to access this value when applying the transformation using the following path at the time {calculate: "datum._source['operators'][0]['name']", as: "Operador"}
  • service_evaluation: is an object that has a field of interest called "category1".

Some documents do not have these fields and I hoped that vega-lite would handle the missing data just as it managed to handle it in another view it had created.

As I started to encounter this "Cannot read property ..." error I decided to create a query that would guarantee the existence of these fields.

I got the result expected by the dev tolls:

So I tried to create a scatterplot between service_evaluation.category1 and queued_duration with a tooltip for other fields:

  name: "conversation",
  $schema: https://vega.github.io/schema/vega-lite/v2.json
 "title": {"text":"Espera Na Fila x Tempo com o Operador",
           "fontSize": 30
 "selection": {
    "paintbrush": {
      "type": "multi",
      "on": "mouseover", "empty": "none"
  data: {
    # URL object is a context-aware query to Elasticsearch
    url: {
      # The %-enclosed keys are handled by Kibana to modify the query
      # before it gets sent to Elasticsearch. Context is the search
      # filter as shown above the dashboard. Timefield uses the value 
      # of the time picker from the upper right corner.
      // %context%: true
      // %timefield%: queued_datetime
      index: prd-inss-omniv2_conversation
      body: {
          "size": 100, 
          "_source": {
            "includes": ["queued_datetime", 
          "query": {
            "bool": {
              "must": [
                  "exists": {
                    "field": "queued_datetime"
                  "exists": {
                    "field": "queued_duration"
                  "exists": {
                    "field": "service_evaluation.category1"
                  "exists": {
                    "field": "operator_duration"
                  "exists": {
                    "field": "operators.name"

        # We only need the content of hits.hits array
        format: {property: "hits.hits"}
  # Parse timestamp into a javascript date value
  transform: [
    {calculate: "toDate(datum._source['queued_datetime'])", 
     as: "tempo"},
    {calculate: "datum._source['operator_duration']", 
    as: "tempo_com_operador"},
    {calculate: "datum._source['queued_duration']", 
    as: "espera_na_fila"},
    {calculate: "datum._source['infos_user']['user_name']", 
    as: "Usuário"},
    {calculate: "datum._source['operators'][0]['name']", 
    as: "Operador"},
    {calculate: "datum._source['groups'][0]['name']", 
    as: "Grupo"}
    {calculate: "datum._source['service_evaluation']['category1']", 
    as: "avaliacao"}
  # Draw a circle, with x being the time field, and y - number of bytes
 "mark": "point",
  encoding: {
    x: {field: "espera_na_fila", 
        type: "quantitative",
        axis: {title: "Tempo de Espera da Fila (min)"}
    y: {field: "avaliacao", type: "quantitative",
       axis: {title: "Avaliação do Serviço (1 a 5 estrelas)"}
   "tooltip": [
      {"field": "espera_na_fila", "type": "quantitative"},
      {field: "tempo_com_operador", type: "quantitative"},
      {field: "Usuário", type: "nominal"},
      {field: "Operador", type: "nominal"},
      {field: "Grupo", type: "nominal"},
      {field: "avaliacao", type: "nominal"},
    color: {field:"Grupo", type:"nominal",
      fill: "#f5425a",
      legend: {title:"Grupo"}
    "size": {
      "condition": {
        "selection": "paintbrush", "value": 500
      "value": 50

But I get the errors:

I used debug to see if the expected values of the query:

I don't know what to do to get rid of such errors and finally access the data that is being returned by the query. Help please!


I don't deal too much in Vega-Lite but calculate transforms work exactly the same as Vega formula transforms. In this regard, they are expressions. You should be able to write a conditional to handle this from now on. Like "datum._source['operator_duration'] ? datum._source['operator_duration'] : 0" or "if(datum._source['operator_duration'], datum._source['operator_duration'], 0)". Basically you have to add in a conditional or else Vega will fail when it cannot find what you are declaring.

Please let me know if that helps!

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.