# Yesod.Auth.OAuth2
OAuth2 `AuthPlugin`s for Yesod.
## Usage
```hs
import Yesod.Auth
import Yesod.Auth.OAuth2.GitHub
instance YesodAuth App where
-- ...
authPlugins _ = [oauth2GitHub clientId clientSecret]
clientId :: Text
clientId = "..."
clientSecret :: Text
clientSecret = "..."
```
Some plugins, such as GitHub and Slack, have scoped functions for requesting
additional information:
```hs
oauth2SlackScoped [SlackBasicScope, SlackEmailScope] clientId clientSecret
```
## Working with Extra Data
We put the minimal amount of user data possible in `credsExtra` -- just enough
to support you parsing or fetching additional data yourself.
For example, if you work with GitHub and GitHub user profiles, you likely
already have a model and a way to parse the `/user` response. Rather than
duplicate all that in our library, we try to make it easy for you to re-use that
code yourself:
```hs
authenticate creds = do
let
-- You can run your own FromJSON parser on the response we already have
eGitHubUser :: Either String GitHubUser
eGitHubUser = getUserResponseJSON creds
-- Avert your eyes, simplified example
Just accessToken = getAccessToken creds
Right githubUser = eGitHubUser
-- Or make followup requests using our access token
runGitHub accessToken $ userRepositories githubUser
-- Or store it for later
insert User
{ userIdent = credsIdent creds
, userAccessToken = accessToken
}
```
**NOTE**: Avoid looking up values in `credsExtra` yourself; prefer the provided
`get` functions. The data representation itself is no longer considered public
API.
## Local Providers
If we don't supply a "Provider" (e.g. GitHub, Google, etc) you need, you can
write your own using our provided `Prelude`:
```haskell
import Yesod.Auth.OAuth2.Prelude
pluginName :: Text
pluginName = "mysite"
oauth2MySite :: YesodAuth m => Text -> Text -> AuthPlugin m
oauth2MySite clientId clientSecret =
authOAuth2 pluginName oauth2 $ \manager token -> do
-- Fetch a profile using the manager and token, leave it a ByteString
userResponse <- -- ...
-- Parse it to your preferred identifier, e.g. with Data.Aeson
userId <- -- ...
-- See authGetProfile for the typical case
pure Creds
{ credsPlugin = pluginName
, credsIdent = userId
, credsExtra = setExtra token userResponse
}
where
oauth2 = OAuth2
{ oauth2ClientId = clientId
, oauth2ClientSecret = Just clientSecret
, oauth2AuthorizeEndpoint = "https://mysite.com/oauth/authorize"
, oauth2TokenEndpoint = "https://mysite.com/oauth/token"
, oauth2RedirectUri = Nothing
}
```
The `Prelude` module is considered public API, though we may build something
higher-level that is more convenient for this use-case in the future.
## Development & Tests
```console
stack setup
stack build --dependencies-only
stack build --pedantic --test
```
Please also run HLint and Weeder before submitting PRs.
---
[CHANGELOG](./CHANGELOG.md) | [LICENSE](./LICENSE)