Redirect style will create new user

[zhaoyao91]

it's fine to link account in popup style, but wechat-mp require to use redirect style, which is a limit of the wechat. could you please support link account with redirect style?

[StorytellerCZ]

I'll have to look into how wechat works and from that figure out where the issue is. I don't use wechat so I won't get to this any time soon, so if someone else wants to look into this, it will be much appreciated.

[StorytellerCZ]

I've looked through the code and I don't see where the issue can originate. Did you make any progress on this @zhaoyao91 ? Did you try the newest version?

[MastroLindus]

This is not related to wechat.
I use google and facebook, and when the flow is set to redirect a new user is created instead of adding the information to the logged in user.

I think it's because Meteor has some logic in accounts-oauth that automatically calls the default oauth login on the server if oauth information is found at page load, and that login handler automatically creates a new user, skipping the call to the callback of this package.

[MastroLindus]

The code that I am talking about is in accounts-oauth:

Meteor.startup(() => {
  const oauth = OAuth.getDataAfterRedirect();
  if (! oauth)
    return;

  // We'll only have the credentialSecret if the login completed
  // successfully.  However we still call the login method anyway to
  // retrieve the error if the login was unsuccessful.

  const methodName = 'login';
  const { credentialToken, credentialSecret } = oauth;
  const methodArguments = [{ oauth: { credentialToken, credentialSecret } }];

  Accounts.callLoginMethod({
    methodArguments,
    userCallback: err => {
      // The redirect login flow is complete.  Construct an
      // `attemptInfo` object with the login result, and report back
      // to the code which initiated the login attempt
      // (e.g. accounts-ui, when that package is being used).
      err = convertError(err);
      Accounts._pageLoadLogin({
        type: oauth.loginService,
        allowed: !err,
        error: err,
        methodName,
        methodArguments,
      });
    }
  });
});

This will call the normal oauth login handler instead of the link

[StorytellerCZ]

@MastroLindus Thanks a lot for locating the code. I will see what we can do to fix this in core.

[micktaiwan]

Same issue here with Google (linkWithGoogle) and loginStyle: "redirect" calls
Some progress on this issue ?

[allenfuller]

It's been a minute since there was conversation on this issue, but I did some digging in Meteor 3. The current OAuth workflow is so deeply ingrained in Meteor across several packages. I honestly don't know how to even begin to weave link-accounts into it.

Apologies if this is repetitive, but it's helpful for me to lay out the whole process.

The block @MastroLindus found several years ago is still in Meteor's core Accounts OAuth package.

But to back up, when a user calls to link with an external service, e.g. Meteor.linkWithGoogle, that kicks off a package within Meteor Link Accounts. But that google package requires accounts-google and google-oauth.

It calls Google.requestCredential which is in the google-oauth package. This then calls OAuth.launchLogin from the oauth package.

OAuth.launchLogin saves two items in local storage for when the redirect is complete: loginService and credentialToken. The redirect workflow then begins based on the service's oauth URL.

When it gets back with the redirect, the oauth package fetches the loginService and credentialToken values it saved previously (via OAuth.getDataAfterRedirect).

Now we're back at the code block from Mastro in Accounts OAuth, where it calls Accounts.callLoginMethod. This method is in the Accounts Base package. I hope you're not making this a drinking game.

We eventually end up back at Accounts.registerLoginHandler, which leads us back into the Google OAuth package in registerLoginHandler. This is where it adds the Google user's name in a profile property (in getServiceDataFromTokens) on the user object.

This, in turn, passes it on to Accounts.updateOrCreateUserFromExternalService in the Accounts Base package. This function will only search for an existing user based on serviceData.id. Of course, the purpose of this package is to link an existing user with a new OAuth account, so that will always return no results and create a new user.

Given this complexity, I'm not sure the best way to pass a userId or other local storage / login URL parameter that could be picked up on the return trip, but it would involve giving Meteor core more flexibility in how it handles the session startup from successful OAuth redirects.

But if anyone has some direction, I'm happy to give it a shot!