topic Re: Asynchronous query calls in ArcGIS JavaScript Maps SDK Questions

Asynchronous query calls

AndrewLeane — Tue, 29 May 2012 06:04:36 GMT

Hi all,

I'm still a newbie with the Javascript API, but my issue seems very similar to one solved on the Flex API forum. I am running multiple queries, and I need to know which layerId the resulting featuresets come from. As the results are asynchronous, I'm not sure which featureset comes from which layer.

The solution on the Flex forum was:

Add the reference to your layer when you do the query like:  queryTask.execute(query, new AsyncResponder(onResult, onFault, myLayerID));  Then define your result handler like :  function onResult(featureSet:FeatureSet, myLayerID:Number):void { ... }

is there a way to do a similar thing in javascript by creating a new AsyncResponder?

Thanks very much
Andrew

Re: Asynchronous query calls

YohanBienvenue — Sun, 12 Dec 2021 03:01:37 GMT

Hi all,

I'm still a newbie with the Javascript API, but my issue seems very similar to one solved on the Flex API forum. I am running multiple queries, and I need to know which layerId the resulting featuresets come from. As the results are asynchronous, I'm not sure which featureset comes from which layer.

The solution on the Flex forum was:
Add the reference to your layer when you do the query like:

queryTask.execute(query, new AsyncResponder(onResult, onFault, myLayerID));

Then define your result handler like :

function onResult(featureSet:FeatureSet, myLayerID:Number):void
{
...
}
is there a way to do a similar thing in javascript by creating a new AsyncResponder?

Thanks very much
Andrew

If the API doesn't provide it to you, I guess you could manually pass the layerId to your callback yourself.
Maybe something like this could work:

function callback(featureset, layerId){
...
}
 
var _this = this;

var query = new esri.tasks.Query();
query.where = "STATE_NAME = 'Washington'";
query.outSpatialReference = {wkid:102100}; 
query.returnGeometry = true;
query.outFields = ["CITY_NAME"];
queryTask.execute(query, function(featureset){ _this.callback.call(_this, featureset, 12); });

.....

queryTask.execute(query, function(featureset){ _this.callback.call(_this, featureset, 14); });

......

etc

Re: Asynchronous query calls

nicogis — Tue, 29 May 2012 18:23:11 GMT

you can also see this sample: http://help.arcgis.com/en/webapi/javascript/arcgis/help/jssamples/query_deferred_list.html

Re: Asynchronous query calls

AndrewLeane — Wed, 30 May 2012 01:52:59 GMT

Thanks Yohan and Domenico, I used the dojo.deferredList - it's a nice neat way to keep track of the order of the queries. I'll have to remember to check all the samples, not just the API.
Thanks again.