topic Re: Fetching values of fields in a feature layer in ArcGIS JavaScript Maps SDK Questions

Fetching values of fields in a feature layer

IsraAlhamood — Tue, 21 Oct 2014 16:05:57 GMT

I'm trying to set the content of an infoTemplate of a feature layer depending on the field value(${OBJECTID})

for example:

if the ${OBJECTID} = 1 then infoTemplate.setContent("Something")

if the ${OBJECTID} = 2 then infoTemplate.setContent("Something2")

but whenever I do it it keeps giving me an error.

Any idea on how can I fetch the field value from the feature selected?

Re: Fetching values of fields in a feature layer

KenBuja — Tue, 21 Oct 2014 16:28:27 GMT

You should be able to do this using the syntax

if (feature.attributes.OBJECTID === 1) {
    infoTemplate.setContent("Something")
} else if (feature.attributes.OBJECTID === 2 {
    infoTemplate.setContent("Something2")
} else ...

You could also use switch instead of if if you have many conditions. Take a look at this post showing some different ways of using them.

Re: Fetching values of fields in a feature layer

IsraAlhamood — Tue, 21 Oct 2014 16:40:59 GMT

what does feature represent? is it the feature layer name?

sorry I'm a beginner in javascript

Re: Fetching values of fields in a feature layer

KenBuja — Tue, 21 Oct 2014 17:54:22 GMT

This is a modification of an existing sample. When you hover over Aiken county, you'll see the content change. The modification is in the countiesGraphicsLayer "mouse_over" event

<!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>QueryTask with geometry, results as an InfoWindow onHover</title>

    <link rel="stylesheet" href="http://js.arcgis.com/3.11/dijit/themes/claro/claro.css">
    <link rel="stylesheet" href="http://js.arcgis.com/3.11/esri/css/esri.css">

    <script src="http://js.arcgis.com/3.11/"></script>
    <script>
      var map;

      require([
        "esri/map",
        "esri/graphic",
        "esri/InfoTemplate",
        "esri/SpatialReference",
        "esri/geometry/Extent",
        "esri/layers/GraphicsLayer",
        "esri/symbols/SimpleFillSymbol",
        "esri/symbols/SimpleLineSymbol",
        "esri/tasks/query",
        "esri/tasks/QueryTask",
        "esri/Color",
        "dojo/domReady!"
      ],
        function (
          Map, Graphic, InfoTemplate, SpatialReference, Extent, GraphicsLayer,
          SimpleFillSymbol, SimpleLineSymbol, Query, QueryTask, Color
        ) {

          map = new Map("mapDiv", {
              basemap: "streets",
              center: [-80.94, 33.646],
              zoom: 8
            });

          map.on("load", setUpQuery);

          function setUpQuery () {
            var queryTask = new QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/3");

            //build query filter
            var query = new Query();
            query.returnGeometry = true;
            query.outFields = ["NAME", "POP2000", "POP2007", "POP00_SQMI", "POP07_SQMI"];
            query.outSpatialReference = { "wkid": 102100 };
            query.where = "STATE_NAME = 'South Carolina'";

            var infoTemplate = new InfoTemplate();
            var content = "<b>2000 Population: </b>${POP2000}<br/>" +
                          "<b>2000 Population per Sq. Mi.: </b>${POP00_SQMI}<br/>" +
                          "<b>2007 Population: </b>${POP2007}<br/>" +
                          "<b>2007 Population per Sq. Mi.: </b>${POP07_SQMI}";
            infoTemplate.setTitle("${NAME}");
            infoTemplate.setContent(content);

            map.infoWindow.resize(245, 125);

            //Can listen for complete event to process results
            //or can use the callback option in the queryTask.execute method.
            queryTask.on("complete", function (event) {
              map.graphics.clear();
              var highlightSymbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID,
                new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                  new Color([255, 0, 0]), 3), new Color([125, 125, 125, 0.35]));

              var symbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID,
                new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                  new Color([255, 255, 255, 0.35]), 1), new Color([125, 125, 125, 0.35]));

              var features = event.featureSet.features;
              var countiesGraphicsLayer = new GraphicsLayer();
              //QueryTask returns a featureSet.
              //Loop through features in the featureSet and add them to the map.
              var featureCount = features.length;
              for (var i = 0; i < featureCount; i++) {
                //Get the current feature from the featureSet.
                var graphic = features; //Feature is a graphic
                graphic.setSymbol(symbol);
                graphic.setInfoTemplate(infoTemplate);

                countiesGraphicsLayer.add(graphic);
              }
              map.addLayer(countiesGraphicsLayer);
              map.graphics.enableMouseEvents();
              //listen for when the mouse-over event fires on the countiesGraphicsLayer
              //when fired, create a new graphic with the geometry from event.graphic
              //and add it to the maps graphics layer
              countiesGraphicsLayer.on("mouse-over",function (event) {
                map.graphics.clear();  //use the maps graphics layer as the highlight layer
                var graphic = event.graphic;
                if (graphic.attributes.NAME === "Aiken") {
                   map.infoWindow.setContent("Found it");
                } else {
                   map.infoWindow.setContent(graphic.getContent());
                }
                map.infoWindow.setTitle(graphic.getTitle());
                var highlightGraphic = new Graphic(graphic.geometry, highlightSymbol);
                map.graphics.add(highlightGraphic);
                map.infoWindow.show(event.screenPoint,
                  map.getInfoWindowAnchor(event.screenPoint));
              });

              //listen for when map.graphics mouse-out event is fired
              //and then clear the highlight graphic
              //and hide the info window
              map.graphics.on("mouse-out", function () {
                map.graphics.clear();
                map.infoWindow.hide();
              });
            });

            queryTask.execute(query);
          }
        });
    </script>
  </head>

  <body class="claro">
    Hover over a county in South Carolina to get more information.
    <div id="mapDiv" style="width:900px; height:600px; border:1px solid #000;"></div>
  </body>
</html>

Re: Fetching values of fields in a feature layer

IsraAlhamood — Wed, 22 Oct 2014 05:24:45 GMT

I still didn't get it.

here's my code:

var map;

function init()

{

map = new esri.Map("mapDiv");

var basemap: new esri.layer.arcGISTiledMapServiceLayer("link");

map.addLayer(basemap);

var content = "Hello!";

var infoTemplate = new esri.InfoTemplate();

infoTemplate.setTitle("<b>${BUILDING_NO}</b>);

infoTemplate.setTitle(content);

var featureLayer = new esri.layers.FeatureLayer("link",

mode:esri.layers.FeatureLayer.MODE_ONDEMAND,

outFields:["*"],

infoTemplate:infoTemplate

});

map.addLayer(featureLayer);

}

What I didn't get is what does feature o graphic(in the other code) suppose to represent.

I tried both ways and it didn't work.

Re: Fetching values of fields in a feature layer

IsraAlhamood — Wed, 22 Oct 2014 07:48:14 GMT

Ken,

It worked thank you so much.

Re: Fetching values of fields in a feature layer

KenBuja — Wed, 22 Oct 2014 12:07:43 GMT

Glad to help. Please remember to mark the correct post as answered. This will help others when searching on this question.