Adding a FeatureLayer ARCGIS JavaScript API

Question

I am currently exploring ArcGIS JavaScript API. I have my own map services and feature services up on my local server. I would want to use the FeatuerLayer to select and highlight feature on the map. But when I add my feature service I get the following error.

TypeError: Unable to draw graphic (geometry:null, symbol:null): _14 is undefined

I am not able to figure out what this could be, and I am not sure if the feature layer has been added to the map or not. How could I check if it has been added? I tried using a dojo.connect method with the FeatureLayer with an onClick event. But this doesn't seem to work. Have placed the code below

Code:

esri.config.defaults.io.proxyUrl = "proxy.ashx";
dojo.require("dijit.layout.BorderContainer");
dojo.require("dijit.layout.ContentPane");
dojo.require("esri.map");
dojo.require("esri.layers.FeatureLayer");
dojo.require("esri.tasks.query");

var map;
var selectionToolbar;
var infoTemplate = new esri.InfoTemplate();
infoTemplate.setTitle("${ROADNAME}");
infoTemplate.setContent("<b>ROAD NAME: </b>${LINK_ID}<br/>" + "<b>CAT</b>${CAT}</b>");

function init() {
  try {
    var initExtent = new esri.geometry.Extent({
      "xmin": 103.55,
      "ymin": 1.13,
      "xmax": 104.16,
      "ymax": 1.56,
      "spatialReference": {
        "wkid": 4326
      }
    });

    map = new esri.Map("map", {
      extent: esri.geometry.geographicToWebMercator(initExtent)
    });

    var basemap = new esri.layers.ArcGISTiledMapServiceLayer("http://server.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer");

    //my map service layer
    var basemap_sing = new esri.layers.ArcGISTiledMapServiceLayer("http://karthikpc:8399/arcgis/rest/services/Carriage_Mercantor/MapServer", {
      displayLevels: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
    });
    // my feature layer which i am not able to use              
    var featureLayer = new esri.layers.FeatureLayer("http://karthikpc:8399/arcgis/rest/services/Carriage_Mercantor/FeatureServer", {
      mode: esri.layers.FeatureLayer.MODE_ONDEMAND,
      infoTemplate: infoTemplate,
      outFields: ["*"]
    });

    map.addLayer(basemap);
    map.addLayer(base_sing);
    map.addLayer(featureLayer);

    dojo.connect(map, "onLoad", initSelectToolbar);
    dojo.connect(featureLayer."onClick", helloworld);
  } catch (e) {
    alert('An error has occurred: ' + e.message);
  }

}

function helloworld() {
  alert("hello world");
}

dojo.addOnLoad(init);

Answer 1

The URL passed to esri.layers.FeatureLayer needs to be for a specific layer. Your code points to the root of the feature service.

To fix this, append the layer index of the layer the URL. For instance, in this feature service, the rivers layer is layer 1. To create a feature layer using this layer, you would use this url: http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Hydrography/Watershed173811/FeatureServer/1. This is shown in the ONDEMAND feature layer sample although the sample uses the map service. If you're only displaying data, you can use either the map service for the feature service. If you want to edit the data via the ArcGIS API for JavaScript, you have to use the feature service URL.

Answer 2

A FeatureLayer ends with a digit, which is more of an array concept.

my/service/url/points/here

vs.

my/feature/url/points/here/0

The first url points to a service containing anywhere from 1 to X Features. Whereas the second url points to a specific Feature inside of that service.

Hope that helps...