MSAL - No Tokens Available when Using IneractionType.Redirect - azure-active-directory

Question

In our application, we authenticate users using AAD, but we authorize users using our own User and Role tables in our local SQL database.
With the old ADAL library, we were able to return users to our callback url, then from there we would grab the JWT token from the ADAL service, and send that token to our server. The server would then validate the token, decode it and grab the email address. We then used our SQL tables to return another JWT that contained the user's identity and all of their roles.
With MSAL, this still works if you use InteractionType.Popup. The response Observable from the loginPopup() method carries the AuthentiationResult, which has an idToken property and an accessToken property. You can easily grab the one you need and you're off to the races.
However, with InteractionType.Redirect we don't get the AuthenticationResult.
I have injected the msalService instance into the our callbackURL's component (called AuthCallbackComponent). I looked everywhere within the msalService for the tokens, but couldn't find them. I even looked in sessionStorage, where I've configured MSAL to cache the token. They are actually in there (under a couple of really funky keys), but not until later. Whether I use ngOnInit, ngAfterViewInit or ngAftercontentInit, the tokens are not there yet. It does work if I set a timeout of 1-2 seconds, but...no. You can never really rely on timeout delays being long enough for all of your users all the time.
We desire to use the Redirect workflow rather than the popup workflow, so it really would be ideal if we can just get the idToken from the MSAL instance.
I found this post here: Retrieve token using msal, which offers some possible solutions, but the suggestions aren't helpful. It talks about a custom MSAL Interceptor, but that seems wrong. That's typically the HTTP interceptor that adds your token to the headers of your service calls. It also says you can subscribe to the callback and "do something with the returned token", but assuming they mean the callback of the msalService.loginRedirect() method, well that is just wrong. It doesn't return anything at all.
Remember, that in the old ADAL library, this worked. Also it still works with InteractionType.Popup (which we can't use). I expect those tokens must be in the MSAL instance somewhere, or else there's a method we can override, a callback we can provide, etc.
Thanks for reading this longer post.

Answer 1

Buried deep within the 10K pages of Microsoft documntation on MSAL, I found this event reference:
https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-angular/docs/v2-docs/events.md#the-inprogress-observable
So I used their example code to come up with my solution, which was to inject the msalBroadcastService into my AuthCallbackComponent. There I subscribe to its msalSubject$, and when a LOGIN_SUCCESS event happens, I can get the accessToken and idToken from the event's payload. Here is some code:
ngOnInit(): void {
this.msalBroadcastService.msalSubject$.pipe(filter((msg: EventMessage) => msg.eventType === EventType.LOGIN_SUCCESS)).subscribe(msg => {
const idToken = (msg.payload as any).idToken;
// now I can call my service method, passing in the idToken
}