我想用我的 Yesod 应用程序实现大文件上传。现在我有:
module Handler.File where
import Import
import System.Random
import System.FilePath
import Control.Monad
import qualified Data.ByteString.Lazy as LBS
import qualified Data.Text.Encoding
-- upload
uploadDirectory :: FilePath -- FIXME: make this configurable
uploadDirectory = "incoming"
randomFileName :: IO FilePath
randomFileName = do
fname'base <- replicateM 20 (randomRIO ('a','z'))
let fname = uploadDirectory </> fname'base <.> "bin"
return fname
fileUploadForm :: Form (FileInfo, Textarea)
fileUploadForm = renderDivs $ (,)
<$> fileAFormReq "Choose a file"
<*> areq textareaField "What's on the file?" Nothing
getFileNewR :: Handler RepHtml
getFileNewR = do
(formWidget, formEnctype) <- generateFormPost fileUploadForm
defaultLayout $ do
setTitle "Upload new file."
$(widgetFile "file-new")
postFileNewR :: Handler RepHtml
postFileNewR = do
user <- requireAuth
((result, formWidget), formEnctype) <- runFormPost fileUploadForm
case result of
FormSuccess (fi,info) -> do
fn <- liftIO randomFileName
liftIO (LBS.writeFile fn (fileContent fi))
let newFile = File (entityKey user) fn info (fileName fi) (fileContentType fi)
fid <- runDB $ insert newFile
redirect (FileViewR fid)
_ -> return ()
defaultLayout $ do
setTitle "Upload new file."
$(widgetFile "file-new")
大部分都很好,除了几个问题:
文件的最大大小约为 2 兆字节。我有一个修复,但这是正确的方法吗?我的修复是在我的应用程序的 Yesod 实例中覆盖 maximumContentLength 方法的默认实现,如下所示:
maximumContentLength _ (Just (FileNewR _)) = 2 * 1024 * 1024 * 1024 -- 2 GB maximumContentLength _ _ = 2 * 1024 * 1024 -- 2 MB
使用的内存量等于文件的大小。这确实是次优的。我想使用http://hackage.haskell.org/packages/archive/wai-extra/1.2.0.4/doc/html/Network-Wai-Parse.html中的 tempFileBackEnd但我不知道如何实际连接它进入我的请求并使其与表单逻辑(隐藏的 _token 字段等)一起使用。
上传是“单次拍摄”:如何使其与基于 Flash/Html5 的上传器一起向用户显示进度的任何示例?