Add support for user object in redirect method

[dukesx]

Description 📓

Its awesome that you can redirect user the way you want but what about authenticating on mobile ? Flutter is a popular framework and has a "flutter-web-auth" library that can help you sign in to oAuth using web based URLs.

The problem

The library says that when you are redirected to sign in page, the sign in button needs to invoke a deeplink (for e.g app://) after successful authentication containing token or etc. so that the app can fetch the URL, split it into chunks and get the required parameters like this:

app://?token=123456&username=casey&last_name=ryback

Now i can redirect app to a static url but i cant append a user to it for my app to fetch it.

The Need

It would be awesome if a user object was available in redirect so that user object properties could be appended to the deeplink and we (flutter developers) could authenticate with our website without the need of using heavy libraries like firebase.

How to reproduce ☕️

I have no idea how to implement this in next-auth but hopefully it shouldn't be a problem since redirection happens after authentication anyway.

Contributing 🙌🏽

Yes, I am willing to help implement this feature in a PR

[stale]

Hi there! It looks like this issue hasn't had any activity for a while. It will be closed if no further activity occurs. If you think your issue is still relevant, feel free to comment on it to keep it open. (Read more at #912) Thanks!

[stale]

Hi there! It looks like this issue hasn't had any activity for a while. To keep things tidy, I am going to close this issue for now. If you think your issue is still relevant, just leave a comment and I will reopen it. (Read more at #912) Thanks!