Fix parsing of docid

Turns out sometimes docid can be a string.

src/HAL/Client.hs

@@ -27,7 +27,7 @@ type Search doc = "search"
   :> QueryParams "fq" Text
   -- pretty much clear, (Asc || Desc) + field you want to sort by
   :> QueryParam "sort" SortField
-  -- permit to start a the x result
+  -- permit to start at the x result
   :> QueryParam "start" Int
   -- use rows to make the request only return the x number of result
   :> QueryParam "rows" Integer

src/HAL/Doc/Corpus.hs

@@ -4,11 +4,13 @@ module HAL.Doc.Corpus where
 
 import GHC.Generics
 
-import Data.Aeson
-import Data.Default
-import Data.Text (pack, Text)
 import Control.Applicative ((<|>))
 import qualified Control.Lens as L
+import Data.Aeson
+import Data.Aeson.Types (Parser, explicitParseField)
+import Data.Default
+import Data.Text (pack, unpack, Text)
+import Text.Read (readMaybe)
 
 import Servant.API (ToHttpApiData(..))
 
@@ -29,8 +31,9 @@ instance Default Corpus where
   def = Corpus def def def def def def def def
 
 instance FromJSON Corpus where
-  parseJSON (Object o) = Corpus <$>
-    (o .: "docid")
+  parseJSON (Object o) =
+    Corpus
+      <$> (explicitParseField docidParser o "docid")
       <*> (o .: "title_s" <|> return [])
       <*> (o .: "abstract_s" <|> return [])
       <*> (o .:? "submittedDate_s")
@@ -39,5 +42,12 @@ instance FromJSON Corpus where
       <*> (o .: "authOrganism_s" <|> return [])
       <*> (o .: "structId_i" <|> return [])
 
+docidParser :: Value -> Parser Int
+docidParser n@(Number _) = parseJSON n
+docidParser (String i) = case (readMaybe $ unpack i :: Maybe Int) of
+  Nothing -> fail $ "cannot parse int for docid"
+  Just i -> pure i
+docidParser v = fail $ "cannot parse docid: " <> show v
+
 instance ToHttpApiData Corpus where
   toUrlPiece _ = "docid,title_s,abstract_s,submittedDate_s,source_s,authFullName_s,authOrganism_s,structId_i"