yesod/yesod-json/Yesod/Json.hs
2011-12-26 10:45:11 -02:00

89 lines
2.5 KiB
Haskell

{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Yesod.Json
( -- * Convert from a JSON value
defaultLayoutJson
, jsonToRepJson
-- * Convert to a JSON value
, parseJsonBody
-- * Compatibility wrapper for old API
, Json
, jsonScalar
, jsonList
, jsonMap
) where
import Yesod.Handler (GHandler)
import Yesod.Content
( ToContent (toContent), RepHtmlJson (RepHtmlJson), RepHtml (RepHtml)
, RepJson (RepJson), Content (ContentBuilder)
)
import Yesod.Core (defaultLayout, Yesod)
import Yesod.Widget (GWidget)
import qualified Data.Aeson as J
import qualified Data.Aeson.Encode as JE
import Data.Aeson.Encode (fromValue)
import Data.Attoparsec.Enumerator (iterParser)
import Data.Text (pack)
import Control.Arrow (first)
import Control.Monad.Trans.Class (lift)
#if MIN_VERSION_aeson(0, 4, 0)
import Data.HashMap.Strict (fromList)
#else
import Data.Map (fromList)
#endif
import qualified Data.Vector as V
import Text.Julius (ToJavascript (..))
import Data.Text.Lazy.Builder (fromLazyText)
import Data.Text.Lazy.Encoding (decodeUtf8)
#if MIN_VERSION_aeson(0, 5, 0)
import Data.Text.Lazy.Builder (toLazyText)
import qualified Blaze.ByteString.Builder.Char.Utf8 as Blaze
#endif
instance ToContent J.Value where
#if MIN_VERSION_aeson(0, 5, 0)
toContent = flip ContentBuilder Nothing
. Blaze.fromLazyText
. toLazyText
. fromValue
#else
toContent = flip ContentBuilder Nothing . fromValue
#endif
-- | Provide both an HTML and JSON representation for a piece of data, using
-- the default layout for the HTML output ('defaultLayout').
defaultLayoutJson :: Yesod master
=> GWidget sub master ()
-> J.Value
-> GHandler sub master RepHtmlJson
defaultLayoutJson w json = do
RepHtml html' <- defaultLayout w
return $ RepHtmlJson html' $ toContent json
-- | Wraps the 'Content' generated by 'jsonToContent' in a 'RepJson'.
jsonToRepJson :: J.Value -> GHandler sub master RepJson
jsonToRepJson = return . RepJson . toContent
-- | Parse the request body as a JSON value.
--
-- /Since: 0.2.3/
parseJsonBody :: GHandler sub master J.Value
parseJsonBody = lift $ iterParser J.json'
type Json = J.Value
jsonScalar :: String -> Json
jsonScalar = J.String . pack
jsonList :: [Json] -> Json
jsonList = J.Array . V.fromList
jsonMap :: [(String, Json)] -> Json
jsonMap = J.Object . fromList . map (first pack)
instance ToJavascript J.Value where
toJavascript = fromLazyText . decodeUtf8 . JE.encode