Hi there, Do you have a recipe for login with Slack? I am using Flutter frontend and python(FastAPI) backend.

Hey @yogeshksoni slack is not an inbuilt provider we have. Please refer to our custom provider method

I am guessing you are referring to this link: https://supertokens.com/docs/thirdpartypasswordless/common-customizations/signup-form/custom-providers

you can use it for both

I can't find the dart frontend code when using custom providers. Can you please share the link?

https://supertokens.com/docs/thirdpartypasswordless/custom-ui/thirdparty-login -> click on mobile tab. Here is a flutter example app as well: https://github.com/supertokens/supertokens-flutter/tree/master/examples/with-thirdparty

thank you

- yes, it would be /auth/callback/slack (assuming the thirdpartyid you have given is slack)

I am creating custom UI using flutter (mac desktop app)

Right. So you need to handle the callback in the same way that you are handling for google

I am not doing much to handle google callback. Google returns the authcode to redirect ui, which is my flutter app. Then I call supertokens signinup post api. I am not sure when exactly /auth/callback/google is being called actually. Unfortunately Slack won't allow me to redirect the auth codes and token directly to my app. They require the redirect URL to be an https link (which is where /auth/slack/callback) comes in. Where can I see the implementation of /auth/slack/callback? What exactly does it do? does it use access_token and id_token to create the user session?

So you need to basically get the tokens provided by slack and call the signinup api from your frontend app.

ok. Then I am back to the same question. If frontend has to call signinup api with token , when exactly is /auth/slack/callback called and why?

That’s not called. I’m not sure what you are referring to

Got it. Thanks. I will have to find a work around. Since Slack mandates me to use an https link for redirect uri, I may have to create an https deep link in my mac app, which can serve as redirect URI. Phew.

Yea, or, you could make an api in your backend which slack calls, and the api then redirects to the deep link of your app

yeah, that could work too. I have to be careful as the access tokens are being exchanged.

You don't really need to exchange the access token in this step. That happens when u call signinup API. Here you only need to do a redirection from your api (which is https) to your app (which is non https).

hmm the way I understand the flow is this 1. user -> signin with slack using slack auth api 2. slack auth server -> return the auth code to redirect_uri. In my future scenario 3. slack auth server -> give code to backend redirect uri 4. backend call deep link (with auth code) -> app gets the auth code 5. app calls supertoken signinup api with code -> supertokens creates session So does the redirection in step 3 not involve exchange of code?

it doesn't invlove code exchange. Code exchange happens when you call the signinup API. Our sdk does it

Here is a code block from your documentation for google sign in, (i have implemented it and it is working). The redirection with auth code happens at googleSignIn.signIn() call and the mac app receives auth code. Supertoken is not involved at this stage at all. This is where I am struggling with Slack. GoogleSignInAccount? account = await googleSignIn.signIn(); if (account == null) { print("Google sign in was aborted"); return; } String? authCode = account.serverAuthCode; if (authCode == null) { print("Google sign in did not return a server auth code"); return; } // Refer to step 2 }

ah yea. Thats cause the google lib does that.

Yeah. I am sure, it will be straight forward after that (hopefully). But I can't get the code from slack because they don't allow redirection to my app directly 😦 . Anyways, I will try to create deep links and see if it helps. Once I receive the code, I will try calling supertokens signinup api

cool!

Thanks