{-
-Copyright (C) 2009, 2010, 2011 Google Inc.
+Copyright (C) 2009, 2010, 2011, 2012 Google Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
, fromJVal
, asJSObject
, asObjectList
+ , tryFromObj
+ , toArray
)
where
import qualified Text.JSON as J
+import Ganeti.BasicTypes
+
-- * JSON-related functions
-- | A type alias for the list-based representation of J.JSObject.
-- | Coneverts a list of JSON values into a list of JSON objects.
asObjectList :: (Monad m) => [J.JSValue] -> m [J.JSObject J.JSValue]
asObjectList = mapM asJSObject
+
+-- | Try to extract a key from a object with better error reporting
+-- than fromObj.
+tryFromObj :: (J.JSON a) =>
+ String -- ^ Textual "owner" in error messages
+ -> JSRecord -- ^ The object array
+ -> String -- ^ The desired key from the object
+ -> Result a
+tryFromObj t o = annotateResult t . fromObj o
+
+-- | Ensure a given JSValue is actually a JSArray.
+toArray :: (Monad m) => J.JSValue -> m [J.JSValue]
+toArray (J.JSArray arr) = return arr
+toArray o = fail $ "Invalid input, expected array but got " ++ show o