Add FromJSON instances for ArticleRecord and @ types

lib/GEODE/Metadata/ArticleRecord.hs

@@ -5,7 +5,7 @@ module GEODE.Metadata.ArticleRecord
   , relativePath
   , uid ) where
 
-import Data.Aeson ((.=), ToJSON(..))
+import Data.Aeson ((.=), FromJSON(..), ToJSON(..))
 import Data.Aeson.KeyMap as KeyMap (fromList)
 import Data.Csv (FromField(..), FromNamedRecord(..), ToNamedRecord(..), ToField(..))
 import GEODE.Metadata.Record (Record(..))
@@ -34,6 +34,8 @@ instance ToJSONObject ArticleRecord where
     <> "volume" .= volume
     <> "article" .= article
 
+instance FromJSON ArticleRecord
+
 instance Record ArticleRecord where
   uid (ArticleRecord {work, volume, article}) =
     printf "%s_%d_%d" (show $ work) volume article

lib/GEODE/Metadata/Types.hs

@@ -4,7 +4,7 @@ module GEODE.Metadata.Types
   , ToJSONObject(..)
   , type (@)(..) ) where
 
-import Data.Aeson (Object, Series, ToJSON(..), Value(..), pairs)
+import Data.Aeson (FromJSON(..), Object, Series, ToJSON(..), Value(..), pairs)
 import Data.Aeson.KeyMap as Object (union)
 import Data.Csv (FromNamedRecord(..), ToNamedRecord(..))
 import Data.HashMap.Strict as Hash (union)
@@ -39,6 +39,5 @@ instance {-# OVERLAPPABLE #-} ToJSONObject a => ToJSON a where
   toJSON = Object . toJSONObject
   toEncoding = pairs . toJSONPairs
 
-instance (ToJSONObject a, ToJSONObject b) => ToJSONObject (a @ b) where
-  toJSONObject (a :@: b) = toJSONObject a `Object.union` toJSONObject b
-  toJSONPairs (a :@: b) = toJSONPairs a <> toJSONPairs b
+instance {-# OVERLAPPABLE #-} (FromJSON a, FromJSON b) => FromJSON (a @ b) where
+  parseJSON o = (:@:) <$> parseJSON o <*> parseJSON o