unique value function

ChristianSailer2 — Mon, 05 Dec 2016 22:26:40 GMT

Simple question:

How do you get unique values (for instance for rendering or calculate statistics) from a feature service where the value can change dynamically?

Re: unique value function

RobertScheitlin__GISP — Sat, 11 Dec 2021 17:24:24 GMT

Christian,

You can use a Query on the layer using returnDistinctValues property of the Query class in the JS API.

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
    <title>Query distinct values without map</title>

    <script src="https://js.arcgis.com/3.18/"></script>
    <script>
      require([
        "dojo/dom", "dojo/on",
        "esri/tasks/query", "esri/tasks/QueryTask", "dojo/domReady!"
      ], function (dom, on, Query, QueryTask) {

        var queryTask = new QueryTask("https://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/Puget_Sound_BG_Food/FeatureServer/0");

        var query = new Query();
        query.returnGeometry = false;
        query.returnDistinctValues = true;
        query.outFields = [
          "COUNTY"
        ];

        on(dom.byId("execute"), "click", execute);

        function execute () {
          query.where = '1=1';
          queryTask.execute(query, showResults);
        }

        function showResults (results) {
          var resultItems = [];
          var resultCount = results.features.length;
          for (var i = 0; i < resultCount; i++) {
            var featureAttributes = results.features[i].attributes;
            for (var attr in featureAttributes) {
              resultItems.push("<b>" + attr + ":</b>  " + featureAttributes[attr] + "<br>");
            }
            resultItems.push("<br>");
          }
          dom.byId("info").innerHTML = resultItems.join("");
        }
      });
    </script>
  </head>

  <body>
    <input id="execute" type="button" value="Get Details">
    <br />
    <br />
    <div id="info" style="padding:5px; margin:5px; background-color:#eee;">
    </div>
  </body>
</html>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: unique value function

ChristianSailer2 — Tue, 06 Dec 2016 08:35:11 GMT

returnDistinctValues property! Ok, didn't think about! Thank you!

Re: unique value function

RobertScheitlin__GISP — Tue, 06 Dec 2016 14:03:43 GMT

Don't forget to mark this question as answered by clicking on the "Correct Answer" link on the reply that answered your question.

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