As per my tongue twister subject I am trying to work with MapImageLayer objects and their sub layers in V4 of the JS API.
I have hydrated a web map into a map object. The web map has a map service (/MapServer), which is hydrated, naturally, to a MapImageLayer object.
However, despite the map service having sub layers, they are not available to the layer object. At least this is what I surmise by interrogating the layer object’s allSubLayers property, which is empty.
I feel like I'm missing a trick here. The API reference talks about working with sub layers but only when defined by the programmer, not coming from a web map.
Ultimately, I aim to set layer definition queries on the sub layers but just need to get those layer objects before queries can be applied.
I have created a test harness below, which illustrates my conundrum:
<DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
<title>Load a basic WebMap - 4.11</title>
<style>
html,
body,
#viewDiv {
padding: 0;
margin: 0;
height: 100%;
width: 100%;
}
</style>
<link rel="stylesheet" href="https://js.arcgis.com/4.11/esri/themes/light/main.css" />
<script src="https://js.arcgis.com/4.11/"></script>
<script>
require(["esri/views/MapView", "esri/WebMap", "esri/config", "esri/widgets/LayerList"], function (MapView, WebMap,
esriConfig, LayerList) {
var webmap = new WebMap({
portalItem: {
// autocasts as new PortalItem()
id: "90613226a9bc41998a1c893d596badc8"
}
});
webmap.when(function () {
var allLayersAndSublayers = webmap.allLayers.flatten(function (item) {
return item.layers || item.sublayers;
});
var layerList = new LayerList({
view: view
});
view.ui.add(layerList, {
position: "top-left"
});
});
/************************************************************
* Set the WebMap instance to the map property in a MapView.
************************************************************/
var view = new MapView({
map: webmap,
container: "viewDiv"
});
});
</script>
</head>
<body>
<div id="viewDiv"></div>
</body>
</html>
Solved! Go to Solution.
Mark,
you have to wait for the MapImageLayer to be loaded completely.
if(item.type === 'map-image'){
item.watch('loaded', function(){
return item.layers || item.sublayers;
});
}
Mark,
you have to wait for the MapImageLayer to be loaded completely.
if(item.type === 'map-image'){
item.watch('loaded', function(){
return item.layers || item.sublayers;
});
}
Thanks Robert,
Thought by waiting for the web map to load that the underlying sub layers would've already loaded.
Got caught out on the classic asynch web programming catch: your object's not fully loaded yet dummy!
I have since been able to confirm that the sub layers are indeed loading if I give them enough time.
Mark