**Note:** For POC purpose when I did the same flow for a single request(without iterating the for loop) with a single continuation object I got the response correctly from the @AuraEnabled apex method to the client-side(lightning controller.js).// Action method
@AuraEnabled(continuation=true cacheable=true)
public static List<continuation> startRequest() {
Map<String,String> headers=new Map<String,String>();
String access_token = 'L90NMyHS2BcLSdtQ2iyJyr1MD5WdGjEt';
headers.put('Content-Type','application/x-www-form-urlencoded');
headers.put('Accept','application/json');
headers.put('Authorization','Bearer ' + access_token);
List<String> folderList = new List<String>{'108947290168', '108950868379'};
List<continuation> lstCon = new List<continuation>();
// Create continuation. Argument is timeout in seconds.
for(String objFol : folderList){
Continuation con = new Continuation(40);
LONG_RUNNING_SERVICE_URL = LONG_RUNNING_SERVICE_URL+'objFol';
// Set callback method
con.continuationMethod='processResponse';
// Set state
// Create callout request
HttpRequest req = new HttpRequest();
req.setMethod('GET');
req.setEndpoint(LONG_RUNNING_SERVICE_URL);
system.debug('req--'+req);
for(String ss : headers.keyset()){
req.setHeader(ss,headers.get(ss));
}
// Add callout request to continuation
String strteemp = con.addHttpRequest(req);
con.state = strteemp;
lstCon.add(con);
}
// Return the continuations
return lstCon;
}
// Callback method
@AuraEnabled(cacheable=true)
public static Object processResponse(List<String> labels, Object state) {
// Get the response by using the unique label
List<String> lstRes = new List<String>();
for(String objStr : labels){
HttpResponse response = Continuation.getResponse(objStr);
// Set the result variable
String result = response.getBody();
lstRes.add(result);
}
return lstRes;
}
Coninuation class does not support JSON serialization
System.JSONException: Type unsupported in JSON: common.apex.api.continuation.Continuation
There may be some special handling by Salesforce when we return only one instance of continuation object from server method. If you inspect the json response coming to UI controler, It returns web service related details (not the fields from continuation object)
- args, user-agent, headers, url and others.
You can implement a workaround by creating a wrapper class like ContinuationWrapper . Store only those details in wrapper which you need in UI controller and send list of the ContinuationWrapper in server response instead of list of Continuation objects
// this is your inner class
public class ContinuationWrapper {
@AuraEnabled
public String continuationMethod;
// add other fields you need in UI controller
public ContinuationWrapper(Continuation con) {
this.continuationMethod = con.continuationMethod;
// populate other fields
}
}
@AuraEnabled(continuation=true cacheable=true)
public static List<ContinuationWrapper> startRequest() {
Map<String,String> headers=new Map<String,String>();
String access_token = 'L90NMyHS2BcLSdtQ2iyJyr1MD5WdGjEt';
headers.put('Content-Type','application/x-www-form-urlencoded');
headers.put('Accept','application/json');
headers.put('Authorization','Bearer ' + access_token);
List<String> folderList = new List<String>{'108947290168', '108950868379'};
List<ContinuationWrapper> lstCon = new List<ContinuationWrapper>();
// Create continuation. Argument is timeout in seconds.
for(String objFol : folderList){
Continuation con = new Continuation(40);
LONG_RUNNING_SERVICE_URL = LONG_RUNNING_SERVICE_URL+'objFol';
// Set callback method
con.continuationMethod='processResponse';
// Set state
// Create callout request
HttpRequest req = new HttpRequest();
req.setMethod('GET');
req.setEndpoint(LONG_RUNNING_SERVICE_URL);
system.debug('req--'+req);
for(String ss : headers.keyset()){
req.setHeader(ss,headers.get(ss));
}
// Add callout request to continuation
String strteemp = con.addHttpRequest(req);
con.state = strteemp;
lstCon.add(new ContinuationWrapper(con));
}
// Return the continuations
return lstCon;
}
// Callback method
@AuraEnabled(cacheable=true)
public static Object processResponse(List<String> labels, Object state) {
// Get the response by using the unique label
List<String> lstRes = new List<String>();
for(String objStr : labels){
HttpResponse response = Continuation.getResponse(objStr);
// Set the result variable
String result = response.getBody();
lstRes.add(result);
}
return lstRes;
}
