A C# example of how to use Twitch's OAuth authorization code flow to generate a user access token (as well as refresh token). We'll be using TwitchLib.Api to make calls to Twitch.
Twitch's OAuth implementation is fairly standard is does not deviate from OAuth standards. At a high level, you'll create an application on Twitch's developer site. This will automatically create a client id, client secret, and you'll have the chance to setup the redirect uri (where the user goes after authenticating on Twitch's auth portal). For this example, you should use "http://localhost:8080/redirect/". When the example application is run, a local web server will be started, listening on port 8080, and will capture the user being bounced to http://localhost:8080/redirect/ post authorization. Twitch sends them to the redirect uri address, along with a few query string parameters, including code. We will extract the code value from the query string, and use it, in combination with the client secret, client id, and redirect uri to complete the authorization flow with Twitch. Twitch will return a payload include access_token, refresh_token, expires_in, scopes, and a few other fields. Most important to us are the tokens and the expires in value. The access token expires at the end of the number of seconds provided in expires_in. You should use the refresh token (which does not expire unless the user revokes access to the application) to request a new access token.
The first step is to create an application on Twitch's developer portal: https://dev.twitch.tv . Login with your Twitch account. After being logged in, on the right side click Register Your Application. Give it a name, and an oAuth redirect url of http://localhost:8080/redirect/. Select a category, and hit the Create button. Click into the application to view its details. You'll find the Client Id (note this), as well as the button called New Secret. Click the button to generate a new secret and note it. At this point you should have a client id and client secret.
OAuth uses granular scope values to determine what kind of priviledges and data an application has access to. For Twitch, you can find the list of available scopes at: https://dev.twitch.tv/docs/authentication#scopes . Note down the scopes you're interested in.
In the Config.cs file, you'll find three fields: TwitchClientId, TwitchRedirectUri, and TwitchClientSecret. Fill in these fields (uri is http://localhost:8080/redirect/).
In Program.cs, around line 10, you'll find a private list variable named scopes containing a number of prepopulated scopes. Feel free to remove/update/change these to your liking.
Run the program. You'll see a couple things printed out, with the most recent being an authorization URL. Visit this URL. If you are not logged in, you'll be logged in. If you are logged in, you'll be asked to authorize your account against the application for the specified scopes. On authorization, you'll be bounced to http://localhost:8080/redirect/ where you should be met with Authorization started! Check your application!. On the application, you'll find something along the lines of:
Authorization success!
User: <username> (id: <userid>)
Access token: <access_token>
Refresh token: <refresh_token>
Expires in: <expires_in_seconds>
Scopes: <csv_of_scopes>
This example calls the Twitch api with the recently generated access token to discover the calling user (username, userid).
- TwitchLib.Api: C# Twitch api library that wraps all Twitch helix, v5, auth and undocumented endpoints, as well as some helper third party stuff.
- Cole (@swiftyspiffy)
Ping me on Twitter: https://twitter.com/swiftyspiffy
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