Track QueryTask request in callback function

Question

I need to perform buffer search for multiple layers in my project. Consider that user is selecting layer and entering radius/uom on the form.

I am doing it following way but due to multiple asynchronous requests, I am not sure how to track querytask request in the callback function. In the following example, I want to know which layer's request has been completed in executeEquipmentSearch. Can we identify that while sending multiple async requests? Is there any alternative in such scenarios?

for (var i = 1; i <= vBufferRows; i++) {

//query task - constructing map service url for the layer

vQueryTask = QueryTask(vMapServiceUrl + '/' + findLayerId(searchParams['bufflayer' + i]));

//gis query

vQuery = new Query();

vQuery.where = 'OBJECTID IN (' + searchParams['objectid'] + ')';

vQuery.returnGeometry = true;

vQuery.outFields = ['*'];

//execute query

vQueryTask.execute(vQuery, executeEquipmentSearch);

}

function executeEquipmentSearch(response) {

var vFeatures = response.features;

for (var j = 0, len = vFeatures.length; j < len; j++) {

//Need to perform buffer search here based on the radius/uom entered on form along with the layer.

}

kenbuja · Answer

What you'll want to do is use the dojo/promise/all. This executes multiple tasks and, when they are all complete, returns an object with the results of the tasks in the same order as the tasks were originally supplied. The code below shows an example using IdentifyTask on multiple services. Identify with Popup