Lightning Components Developer Guide
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Cancel an Asynchronous Request in a Flow Local Action
If an asynchronous request times out, the flow executes the Local Action element's
fault connector and sets $Flow.FaultMessage to the error message. However,
the original request isn't automatically canceled. To abort an asynchronous request, use the
cancelToken parameter available in the invoke method.
Example
In this client-side controller, the invoke method returns a Promise. When the method has done all it needs to do, it completes the call and control returns to the flow.
- If the request is successful, the method uses resolve() to execute the next element in the flow after this action.
- If the request isn't successful, it uses reject() to execute the Local Action element’s fault connector and sets $Flow.FaultMessage to “My error message”.
- If the request takes too long, it uses cancelToken.promise.then to abort the request.
1({
2 invoke : function(component, event, helper) {
3 var cancelToken = event.getParam("arguments").cancelToken;
4
5 return new Promise(function(resolve, reject) {
6 var xhttp = new XMLHttpRequest();
7
8 // Do something, like get data from
9 // a database behind your firewall
10 xhttp.onreadystatechange = $A.getCallback(function() {
11 if (/* request was successful */) {
12 // Complete the call and return to the flow
13 resolve();
14 } else {
15 reject(new Error("My error message"));
16 }
17 });
18
19 // If the Promise times out, abort the request and
20 // pass set $Flow.FaultMessage to "Request timed out"
21 cancelToken.promise.then(function(error) {
22 xhttp.abort();
23 reject(new Error("Request timed out."));
24 });
25
26 });
27 }
28})