Snap界面 - 获取操作系统和浏览器信息

Question

我正在使用Snap信息，我想知道是否有某种类型的Request函数（例如:: Request - ＆gt; IO Snap（）或:: Request - ＆gt; Handler App App（））返回访问网页的用户的操作系统或浏览器信息。

我想获取正在访问该网页的人的操作系统和浏览器信息。

Answer 1

您可以通过getHeader获取User-Agent HTTP标头，因为Request有HasHeaders个实例。

示例摘录：

import qualified Data.ByteString.Char8 as CS
import qualified Data.CaseInsensitive as CI
import Data.Maybe (listToMaybe)

uaName :: ByteString
uaName = CS.pack "User-Agent"
-- You can avoid CS.pack with OverloadedStrings extension.

uahName :: CI ByteString
uahName = CI.mk uaName
-- OverloadedStrings also gets rid of the CI.mk call.

getUserAgent :: Request -> Snap (Maybe ByteString)
getUserAgent rq = return . coerce $ getHeader uahName rq
 where 
    coerce :: Maybe [ByteString] -> Maybe ByteString
    coerce = (>>= listToMaybe)
    -- Some HTTP headers can appear multiple times, hence the list.
    -- `coerce` ignores all but the first occurrence.

对于更详细/更少自愿的信息，您可以将JS注入初始请求并设置可以在过滤请求中使用rqCookies提取的Cookie。