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convert buffer Circle to polygon to use as Query.geometry

TracySchloss

I have a series of points that I have buffered and generated as Circles. I now want those circles to be used to select features from my featureLayer. I'm getting stuck on the input geometry, because Circle is not in the list of acceptable geometry types for Query. It lists Extent, Point, Multipoint, Polyline, or Polygon

I need to be precise, so I don't want to just use the extent of the circle as my input. I assume there is a way to convert my circles to polygons, but I haven't figured out how to do it yet.

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Accepted answers

RobertScheitlin__GISP

Tracy,

I can confirm that a circle does working in a query.

Here is a sample app:

<!DOCTYPE html>
<html>

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <!--The viewport meta tag is used to improve the presentation and behavior of the samples 
      on iOS devices-->
  <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
  <title>Buffer</title>
  <link rel="stylesheet" href="http://js.arcgis.com/3.11/dijit/themes/tundra/tundra.css">
  <link rel="stylesheet" href="http://js.arcgis.com/3.11/esri/css/esri.css">
  <style>
    html,
    body,
    #mapDiv {
      padding: 0;
      margin: 0;
      height: 100%;
    }
    #messages {
      background-color: #fff;
      box-shadow: 0 0 5px #888;
      font-size: 1.1em;
      max-width: 15em;
      padding: 0.5em;
      position: absolute;
      right: 20px;
      top: 20px;
      z-index: 40;
    }
    #drop {
      background-color: #fff;
      box-shadow: 0 0 5px #888;
      font-size: 1.1em;
      max-width: 15em;
      padding: 0.5em;
      position: absolute;
      right: 20px;
      top: 105px;
      z-index: 40;
    }
  </style>
  <script src="http://js.arcgis.com/3.11/"></script>
  <script>
    var map;


    require([
        "esri/map", "esri/layers/FeatureLayer",
        "esri/tasks/query", "esri/geometry/Circle", "esri/units",
        "esri/graphic", "esri/InfoTemplate", "esri/symbols/SimpleMarkerSymbol",
        "esri/symbols/SimpleLineSymbol", "esri/symbols/SimpleFillSymbol", "esri/renderers/SimpleRenderer",
        "esri/config", "esri/Color", "dojo/dom", "dijit/form/ComboBox", "dojo/domReady!"
      ], function (
      Map, FeatureLayer,
      Query, Circle, Units,
      Graphic, InfoTemplate, SimpleMarkerSymbol,
      SimpleLineSymbol, SimpleFillSymbol, SimpleRenderer,
      esriConfig, Color, dom
    ) {
      // use a proxy page if a URL generated by this page is greater than 2000 characters
      //
      // this should not be needed as nearly all query & select functions are performed on the client
      esriConfig.defaults.io.proxyUrl = "/proxy/";

      map = new Map("mapDiv", {
        basemap: "streets",
        center: [-81.00, 34.000],
        zoom: 14,
        slider: false
      });

      //add the census block points in on demand mode. Note that an info template has been defined so when 
      //selected features are clicked a popup window will appear displaying the content defined in the info template.
      var featureLayer = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/0", {
        outFields: ["POP2000", "HOUSEHOLDS", "HSE_UNITS", "TRACT", "BLOCK"]
      });

      // selection symbol used to draw the selected census block points within the buffer polygon
      var symbol = new SimpleMarkerSymbol(
        SimpleMarkerSymbol.STYLE_CIRCLE,
        6,
        new SimpleLineSymbol(
          SimpleLineSymbol.STYLE_NULL, new Color([200, 120, 101, 0.9]), 1),
        new Color([200, 0, 0, 1])
      );
      featureLayer.setSelectionSymbol(symbol);

      //make unselected features invisible
      var nullSymbol = new SimpleMarkerSymbol().setSize(0);
      featureLayer.setRenderer(new SimpleRenderer(nullSymbol));

      map.addLayer(featureLayer);


      var circleSymb = new SimpleFillSymbol(
        SimpleFillSymbol.STYLE_NULL,
        new SimpleLineSymbol(
          SimpleLineSymbol.STYLE_SHORTDASHDOTDOT,
          new Color([105, 105, 105]),
          2
        ), new Color([255, 255, 0, 0.25])
      );
      var circle;

      //when the map is clicked create a buffer around the click point of the specified distance.
      map.on("click", function (evt) {
        selbuf = document.FormSelection.BufferSelection.selectedIndex;
        var BufferSelection = document.FormSelection.BufferSelection.options[selbuf].value;

        circle = new Circle({
          center: evt.mapPoint,
          geodesic: true,
          radius: BufferSelection,
          radiusUnit: Units.MILES
        });
        map.graphics.clear();
        map.infoWindow.hide();
        var graphic = new Graphic(circle, circleSymb);
        map.graphics.add(graphic);

        var query = new Query();
        query.geometry = circle;
        featureLayer.selectFeatures(query, FeatureLayer.SELECTION_NEW, function (results) {
          var totalPopulation = sumPopulation(results);
          var r = "";
          r = "<b>The total Census Block population within the buffer is <i>" + totalPopulation + "</i>.</b>";
          dom.byId("messages").innerHTML = r;
        });
      });

      function sumPopulation(features) {
        var popTotal = 0;
        for (var x = 0; x < features.length; x++) {
          popTotal = popTotal + features.attributes["POP2000"];
        }
        return popTotal;
      }
    });
  </script>
</head>

<body>
  <span id="messages">Click on the map to select census block points within mile.</span>
  <span id="drop">
    <form name="FormSelection">
     <select name="BufferSelection"> 
           <option>1</option>
        <option>2</option>
        <option>10</option>
     </select>
    </form>
  </span>
  <div id="mapDiv"></div>
</body>

</html>

All comments

TracySchloss

I could only get this to work with the extent of the graphic, not the actual geometry of the circle, which was my original question. I guess the answer is, Circle isn't interpreted as a Polygon in this situation.

RobertScheitlin__GISP

Tracy,

Your queryFeatures method call is incorrect.

primaryLayer.queryFeatures(query, FeatureLayer.SELECTION_ADD, function (result){

It should just be:

primaryLayer.queryFeatures(query,  function (result){

You only do the FeatureLayer.SELECTION_ADD if you are using the

selectFeatures(query, selectionMethod?, callback?, errback?).

The difference between queryFeatures and selectFeatures is pretty big.

queryFeatures will return geometry and attributes that meet you query criteria where as selectFeatures will do the same and actually change the symbology of the selected features in your FeatureLayer.

TracySchloss

That's what I thought to, but my featureLayer query keeps failing. I put my buffered points into a graphicsLayer (the one you just helped me with the attributes).

I need to know if any features in my featureLayer as within a set distance to other features in that same layer. Plus I have a 2nd layer that I need to query as well, which I'll get to next. I figured using a separate graphicLayer would help with this, plus I needed the graphics to display anyway.

function selectAllInBuffer(){

primaryLayer.clearSelection();//my featureLayer

arrayUtils.forEach(bufferLayer.graphics, function (graphic){//my graphics layer full of circles

var query = new Query();

query.geometry = graphic.geometry;

primaryLayer.queryFeatures(query, FeatureLayer.SELECTION_ADD, function (result){

console.log('queryResult');//just so I had a place to put a breakpoint

});

Am I not accessing the graphics of my graphicsLayers correctly? It seems pretty straight forward.

Have you ever gotten a clear idea of the different between queryFeatures and selectFeatures? It seems like I read something a while ago, but the explanation was too obscure to make much sense.

kenbuja

According to the documentation, a Circle is a subclass of a Polygon.

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