Merge pull request #196 from meteficha/yesod-json-more-generic

More generic types on Yesod.Json using FromJSON/ToJSON.

yesod-json/Yesod/Json.hs

@@ -5,8 +5,10 @@ module Yesod.Json
     ( -- * Convert from a JSON value
       defaultLayoutJson
     , jsonToRepJson
+
       -- * Convert to a JSON value
     , parseJsonBody
+
       -- * Produce JSON values
     , J.Value (..)
     , object
@@ -20,6 +22,7 @@ import Yesod.Content
     )
 import Yesod.Core (defaultLayout, Yesod)
 import Yesod.Widget (GWidget)
+import Control.Arrow (second)
 import qualified Data.Aeson as J
 import qualified Data.Aeson.Encode as JE
 import Data.Aeson.Encode (fromValue)
@@ -40,35 +43,44 @@ instance ToContent J.Value where
               . toLazyText
               . fromValue
 
--- | 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
+-- | Provide both an HTML and JSON representation for a piece of
+-- data, using the default layout for the HTML output
+-- ('defaultLayout').
+--
+-- /Since: 0.3.0/
+defaultLayoutJson :: (Yesod master, J.ToJSON a)
+                  => GWidget sub master ()  -- ^ HTML
+                  -> a                      -- ^ JSON
                   -> GHandler sub master RepHtmlJson
 defaultLayoutJson w json = do
     RepHtml html' <- defaultLayout w
-    return $ RepHtmlJson html' $ toContent json
+    return $ RepHtmlJson html' $ toContent (J.toJSON 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.
+-- | Wraps a data type in a 'RepJson'.  The data type must
+-- support conversion to JSON via 'J.ToJSON'.
 --
--- /Since: 0.2.3/
-parseJsonBody :: GHandler sub master J.Value
+-- /Since: 0.3.0/
+jsonToRepJson :: J.ToJSON a => a -> GHandler sub master RepJson
+jsonToRepJson = return . RepJson . toContent . J.toJSON
+
+-- | Parse the request body to a data type as a JSON value.  The
+-- data type must support conversion from JSON via 'J.FromJSON'.
+-- If you want the raw JSON value, just ask for a @'J.Result'
+-- 'J.Value'@.
+--
+-- /Since: 0.3.0/
+parseJsonBody :: J.FromJSON a => GHandler sub master (J.Result a)
 parseJsonBody = do
     req <- waiRequest
-    lift $ requestBody req $$ sinkParser J.json'
+    fmap J.fromJSON $ lift $ requestBody req $$ sinkParser J.json'
 
 instance ToJavascript J.Value where
     toJavascript = fromLazyText . decodeUtf8 . JE.encode
 
 -- | Convert a list of pairs to an 'J.Object'.
-object :: [(Text, J.Value)] -> J.Value
-object = J.object
+object :: J.ToJSON a => [(Text, a)] -> J.Value
+object = J.object . map (second J.toJSON)
 
 -- | Convert a list of values to an 'J.Array'.
-array :: [J.Value] -> J.Value
-array = J.Array . V.fromList
+array :: J.ToJSON a => [a] -> J.Value
+array = J.Array . V.fromList . map J.toJSON