featurelayers.graphics

DamNguyen

Hi guys,

I'm working on a map that uses FeatureLayer.Mode_ONDEMAND. To see certain layer, I pass in a project ID using featureLayer.setDefinitionExpression. Where such layer exists, I see it. What I want to know is how to detect when no layer exists. I want to print an alert to the viewer instead of showing just a blank map. Here's my code:

function init() {

  map = new esri.Map("mapDiv", {

   basemap: "topo",

   center: [-116.73536, 33.033989],

   zoom: 9

  });

  var featureLayer = new esri.layers.FeatureLayer("http://services.arcgis.com/v01gqwM5QqNysAAi/arcgis/rest/services/Project_boundaries_021616/FeatureServer/0",{

   mode: esri.layers.FeatureLayer.MODE_ONDEMAND,

   outFields: ["*"],

   opacity: 1

  });

  featureLayer.setDefinitionExpression("SrvyDescID=\'' . htmlspecialchars($ProjectID) . '\'");

  console.log(featureLayer.graphics);

  console.log(featureLayer.graphics[0]);

  map.addLayer(featureLayer);

   }

What I learned is when the project is valid, feature.graphics will return an array. But I'm unable to treat it like an array. For example, featureLayer.graphic[0] returns "undefined". featureLayer.graphic.length also doesn't work. And yet, my console.log does return an object. How do I detect this object?

Attached is a screenshot of the console log. Thanks for your help.

Untitled-1.png

DamNguyen

It turns out, instead of catching layer-add-result event, I needed to catch update-end event.

This is what I ended up with:

map = new esri.Map("mapDiv", {   center: [-118.30, 34.3],   zoom: 8,   basemap: "topo"   });      on(map, "update-end", function(){   // update-end event will execute after the layer has been added to the map       if(featureLayer.graphics.length >= 1)       {           // do your thing here       }   })          var featureLayer = new esri.layers.FeatureLayer("http://services.arcgis.com/v01gqwM5QqNysAwas/arcgis/rest/services/Project_boundaries_021616/FeatureServer/0",{       mode: esri.layers.FeatureLayer.MODE_ONDEMAND,       outFields: ["*"],       opacity: 1   });   featureLayer.setDefinitionExpression("SrvyDescID=\'' . htmlspecialchars($SDID) . '\'");   map.addLayer(featureLayer);