topic Re: Select with Multipoint in ArcGIS JavaScript Maps SDK Questions

Select with Multipoint

TimWitt2 — Sun, 12 Dec 2021 00:25:53 GMT

Hey everybody,

tagging on to this discussion, I had another question. Robert Scheitlin, GISP was able to help me out per usual, but I ran into another problem. I want to use a Multipoint Geometry to select all features in a polygon that intersect with a point from the multipoint geometry.

Here is the code I have so far:

var myButton2 = new Button({
  label: "Analyze",
  onClick: function(){
  //var selectedCity = [];
  //var allPoints = [];
  var mp = new Multipoint();  
  arrayUtils.map(NewLayer.graphics, function(gra){  
  mp.addPoint(gra.geometry);  
  //allPoints.push(gra);
  });  
  console.log(mp);
  var query = new Query();
  //for (var i = 0; i < allPoints.length; i++) {
  //query.geometry = allPoints.geometry;
  //thisIsaTest = ft6select.selectFeatures(query,FeatureLayer.SELECTION_ADD, function(evt2){
  //if(evt2.length > 0){
  //var tutu = evt2[0].geometry;
  //selectedCity.push(tutu);
  //console.log(selectedCity);
  //}
  //});
  //}
  console.log(selectedCity);
  query.geometry = mp;
  ft6select.selectFeatures(query);
  }
}, "progButtonNode2").startup();


ft6select.on('selection-complete', function (evt){
  console.log(evt);
});

This code returns an empty array, meaning nothing has been selected. When I use the commented out method, using each point of the multipoint geometry, it does select features that intersect with each point.

I hope this makes any sense.

Tim

Re: Select with Multipoint

RobertScheitlin__GISP — Sun, 12 Dec 2021 00:25:55 GMT

Tim,

You just need to set the new multiPoints spatialReference.

mp.spatialReference = evt.target.graphics[0].geometry.spatialReference;

Here is my test sample:

<!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>Drop Down Test</title>
  <link rel="stylesheet" href="http://js.arcgis.com/3.13/dijit/themes/claro/claro.css">
  <link rel="stylesheet" href="http://js.arcgis.com/3.13/dojo/resources/dojo.css">
  <link rel="stylesheet" href="http://js.arcgis.com/3.13/esri/css/esri.css">
  <script src="http://js.arcgis.com/3.13/"></script>
  <style>
    html,
    body,
    #mainWindow {
      height: 100%;
      width: 100%;
      margin: 0;
      padding: 0;
    }
    body {
      background-color: #FFF;
      overflow: hidden;
      font-family: "Trebuchet MS";
    }
  </style>

  <script>
    var map;
    require([
      "esri/map",
      "dojo/on",
      "esri/tasks/query",
      "esri/layers/FeatureLayer",
      "esri/geometry/Multipoint",
      "dojo/store/Memory",
      "dojo/_base/array",
      "dojo/_base/lang",
      "esri/request",
      "dojo/json",
      "dojo/parser",
      "dijit/layout/BorderContainer",
      "dijit/layout/ContentPane",
      "dijit/form/Button",
      "dijit/form/ComboBox",
      "dojo/domReady!"
    ], function(
      Map, on, Query, FeatureLayer, Multipoint, Memory, array, lang, esriRequest, json, parser
    ) {
      parser.parse();
      map = new Map("map", {
        basemap: "topo",
        center: [-98.1883, 37.0868],
        zoom: 5
      });

      var Points = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/0", {
        mode: FeatureLayer.MODE_SNAPSHOT,
        outFields: ["*"]
      });

      var BlockGrp = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/1", {
        mode: FeatureLayer.MODE_SELECTION,
        outFields: ["*"]
      });
      BlockGrp.setMinScale(0);
      BlockGrp.setMaxScale(0);


      Points.setDefinitionExpression("STATE_FIPS = '01' AND CNTY_FIPS = '015' AND BLOCK = '3039'");
      Points.setMinScale(0);
      Points.setMaxScale(0);
      Points.on('update-end', function(evt){
        var mp = new Multipoint();
        array.map(evt.target.graphics, function(gra){
          mp.addPoint(gra.geometry);
        });
        mp.spatialReference = evt.target.graphics[0].geometry.spatialReference;
        console.info(mp);
        var query = new Query();
        query.geometry = mp;
        BlockGrp.selectFeatures(query);
      })
      map.addLayers([Points, BlockGrp]);

      BlockGrp.on('selection-complete', function (evt){
        console.log(evt);
      });

    });
  </script>
</head>

<body class="claro">
  <div id="mainWindow" data-dojo-type="dijit/layout/BorderContainer" data-dojo-props="design:'headline', gutters:false" style="padding:0px;margin:0px;">
  </div>
</body>

</html>

Re: Select with Multipoint

thejuskambi — Mon, 20 Jul 2015 14:33:55 GMT

The multipoint geometry may be missing the Spatialreference information. try to initialize it like this

var multiPoint = new Multipoint(new SpatialReference({ wkid:4326 }));

with appropriate projection system value.

Re: Select with Multipoint

TimWitt2 — Mon, 20 Jul 2015 14:46:34 GMT

Thanks Robert and Thejus, this was exactly it!

When I use the commented out method, my selectedCity array is empty, even though I push each selection in it. While the for loop runs you can see the selectedCity filling up with each push, but once the for loop is done it is empty. Any idea why this happens?

Re: Select with Multipoint

RobertScheitlin__GISP — Mon, 20 Jul 2015 14:56:56 GMT

Tim,

It is a scope issue as your selection complete function is in a different scope then the rest of your function. This is where you would use lang.hitch.

Re: Select with Multipoint

TimWitt2 — Mon, 20 Jul 2015 15:01:01 GMT

How would I use it in this particular case? I have a hard time understanding how it works and this example might clear it up.

Re: Select with Multipoint

RobertScheitlin__GISP — Sun, 12 Dec 2021 00:25:58 GMT

Tim,

Here it is added to your code:

      var myButton2 = new Button({
        label: "Analyze",
        onClick: function(){
        var selectedCity = [];
        var allPoints = [];
        var mp = new Multipoint();
        arrayUtils.map(NewLayer.graphics, function(gra){
          mp.addPoint(gra.geometry);
          allPoints.push(gra);
        });
        console.log(mp);
        var query = new Query();
        for (var i = 0; i < allPoints.length; i++) {
          query.geometry = allPoints.geometry;
          thisIsaTest = ft6select.selectFeatures(query,FeatureLayer.SELECTION_ADD, lang.hitch(this, function(evt2){
            if(evt2.length > 0){
              var tutu = evt2[0].geometry;
              selectedCity.push(tutu);
              console.log(selectedCity);
            }
          }));
        }
        console.log(selectedCity);
        query.geometry = mp;
        ft6select.selectFeatures(query);
        }
      }, "progButtonNode2").startup();  

      ft6select.on('selection-complete', function (evt){  
        console.log(evt);  
      });

Re: Select with Multipoint

TimWitt2 — Mon, 20 Jul 2015 15:16:40 GMT

Thanks again Robert!