We would like to enable WeChat Login on our iOS client that is connected to a Parse Server backend on Heroku. From reading through the PFFacebookAuthenticationProvider, it seems that we need to write a custom authentication provider for WeChat.
WeChat Login is based on OAuth 2.0. It works as followed: 1. From our app, an authorization request is sent to the WeChat app installed on the same phone. WeChat app is called to the foreground. 2. After user approved the authorization request, a code (NOT the access token) is sent to our app. 3. With the code and our app id and app secret, our server can then call WeChat API and get the appropriate user id and access token from WeChat. This step has to happen on our server, as we cannot include the app secret within our client app.
On the WeChat documentation, it is strongly recommended that we keep the access token strictly in the control of server (anyone with the access token can make requests to WeChat API and it will be counted towards the usage limit for our API calls).
If we are to follow this practice, we cannot save the access token in the authData field of the user. Would it be acceptable to save only the code and id from WeChat into the authData and save the access token to another class that only the master key has access to? This obviously requires us to write a custom AuthAdapter for the Parse Server.
Or is there a better way to implement this custom auth? The custom auth documentation for Parse Server is pretty thin and I plan to improve it after I can get it working for myself.
You can definitely update the auth adapter to exchange the code for an access token server side. The logic would be similar to other adapters, failing to login/signup if the server is unable to process the code to access token exchange.
Here https://github.com/parse-community/parse-server/blob/master/src/Adapters/Auth/wechat.js#L7
If the authData object has that code, you can add additional logic to exchange it.