如何在Servant中获取HTTP头？

Question

我有一个简单的服务应用程序，带有 REST API：

type API = "items" :> Get '[JSON] [MyData]

app :: Application
app = serve api server

api :: Proxy API
api = Proxy

server :: Server API
server = getItems

getItems :: ExceptT ServantErr IO [MyData]
getItems = ......

startApp :: IO ()
startApp = run 1234 app

我该如何获取HTTP头并根据条件返回特定的响应，比如HTTP403？

- user266003

Answer 1

使用Servant的Header（Servant文档）

type API = "items" 
           :> Header "Auth-token" Text 
           :> Get '[JSON] [MyData]

那么

handler :: Maybe Text -> ExceptT ServantErr IO [MyData]
handler (Just "secret-code") = right [mydata]
handler _                    = left $ err403 { errBody = "no access" }

- josejuan

---

如果我没记错的话，你会得到 Maybe String，但这个答案除此之外还是不错的。 - Alp Mestanogullari