Callback was already called error from async

[lavayj]

const sp = new saml2.ServiceProvider(sso_options.sp_options);
const params = querystring.parse(event.body);

// Our field from the request.
const samlResponse = params['SAMLResponse'];

log.debug(samlResponse);
const req ={};
req.SAMLResponse = samlResponse;
const options = {request_body:req};
const idp = new saml2.IdentityProvider(sso_options.idp_options);
log.debug(options);
sp.post_assert(idp,options,function(err, assertionResponse){
if(err){
log.error(err);
throw(err);
} else {

log.debug(assertionResponse);
const userId = assertionResponse.user.name_id;
const firstName = assertionResponse.user.attributes.firstName[0];
const lastName = assertionResponse.user.attributes.lastName[0];
const email = assertionResponse.user.attributes.email[0];
const accessToken = auth.createAccessToken(userId,firstName,lastName,email,'User');

}})})

I get the below error after i receive the assertionResponse and see the log statement. It seems the callback is invoked before completion of the async calls. What could be the issue ?

2017-09-29T16:58:01.202Z 58dea4fa-a537-11e7-ac37-2b1c78b060d2 Error: Callback was already called.
at /var/task/node_modules/saml2-js/node_modules/async/dist/async.js:903:32
at /var/task/node_modules/saml2-js/lib-js/saml2.js:658:16
at nextTask (/var/task/node_modules/saml2-js/node_modules/async/dist/async.js:5297:14)
at next (/var/task/node_modules/saml2-js/node_modules/async/dist/async.js:5304:9)
at /var/task/node_modules/saml2-js/node_modules/async/dist/async.js:906:16
at /var/task/node_modules/saml2-js/lib-js/saml2.js:633:20
at nextTask (/var/task/node_modules/saml2-js/node_modules/async/dist/async.js:5297:14)
at next (/var/task/node_modules/saml2-js/node_modules/async/dist/async.js:5304:9)
at /var/task/node_modules/saml2-js/node_modules/async/dist/async.js:906:16
at /var/task/node_modules/saml2-js/lib-js/saml2.js:607:16

[rahil471]

Any solution to thsi issue?

[rahil471]

I changed the version to 1.11.1. To fix this. I think the new versions included this bug.

[HardDoer]

This is true. Changing the version to 1.11.1 fixed this for me as well.

[chveragad]

May i know what was the actual fix on the version 1.11.1 so I can check if this was actually in the later versions? Thanks

[gabegorelick]

#112 fixed an instance of this.

[ComfyDust]

Ran into this issue recently and found the cause, at least for my instance.

After post_assert() returned successfully without error, I mistakenly tried to iterate over response.user with for (let attribute of response.user). Internally the callback function threw TypeError: response.user is not iterable.

This error was then caught in the waterfall and the code attempted to execute the callback again, this time with the TypeError. This leads to the async package swallowing the original error and throwing its own since the code attempted to execute the callback twice.

I suspect this error might happen if there's any runtime error in the callback. As a workaround until there's a fix it may help to wrap any custom callbacks in a giant try/catch block while debugging.

[nthgol]

@ComfyDust thanks for your comment, this led us to a quick fix, indeed you were right. We wrapped our entire callback in a try catch and logged the error in the catch to debug

[pooledge]

@ComfyDust this comment is terribly underrated