Ignore updates that produce parse failures, allowing bots to partiall…

…y work after API changes on the side of telegram

telegram-bot-api/src/Telegram/Bot/API/GettingUpdates.hs

@@ -6,7 +6,7 @@
 {-# LANGUAGE TypeOperators              #-}
 module Telegram.Bot.API.GettingUpdates where
 
-import           Data.Aeson                      (FromJSON (..), ToJSON (..))
+import           Data.Aeson                      (FromJSON (..), ToJSON (..), Value)
 import           Data.Foldable                   (asum)
 import           Data.Proxy
 import           GHC.Generics                    (Generic)
@@ -70,8 +70,10 @@ extractUpdateMessage Update{..} = asum
 
 -- ** 'getUpdates'
 
-type GetUpdates
-  = "getUpdates" :> ReqBody '[JSON] GetUpdatesRequest :> Get '[JSON] (Response [Update])
+type GetUpdatesAs a
+  = "getUpdates" :> ReqBody '[JSON] GetUpdatesRequest :> Get '[JSON] (Response [a])
+
+type GetUpdates = GetUpdatesAs Update
 
 -- | Use this method to receive incoming updates using long polling.
 -- An list of 'Update' objects is returned.
@@ -82,6 +84,14 @@ type GetUpdates
 getUpdates :: GetUpdatesRequest -> ClientM (Response [Update])
 getUpdates = client (Proxy @GetUpdates)
 
+-- | More liberal version of `getUpdates` funcion.
+--
+-- It's useful  when you aren't sure that you can
+-- parse all the types of updates, so you would recieve
+-- a list of Value with updates, that you can parse later.
+getUpdatesAsValue :: GetUpdatesRequest -> ClientM (Response [Value])
+getUpdatesAsValue = client (Proxy @(GetUpdatesAs Value))
+
 -- | Request parameters for 'getUpdates'.
 data GetUpdatesRequest = GetUpdatesRequest
   { getUpdatesOffset         :: Maybe UpdateId -- ^ Identifier of the first update to be returned. Must be greater by one than the highest among the identifiers of previously received updates. By default, updates starting with the earliest unconfirmed update are returned. An update is considered confirmed as soon as getUpdates is called with an offset higher than its update_id. The negative offset can be specified to retrieve updates starting from -offset update from the end of the updates queue. All previous updates will forgotten.

telegram-bot-simple/src/Telegram/Bot/Simple/BotApp/Internal.hs

@@ -16,6 +16,8 @@ import qualified System.Cron             as Cron
 
 import qualified Telegram.Bot.API        as Telegram
 import           Telegram.Bot.Simple.Eff
+import Data.Either (partitionEithers)
+import Data.Aeson.Types (parseEither, parseJSON)
 
 -- | A bot application.
 data BotApp model action = BotApp
@@ -141,7 +143,7 @@ startPolling handleUpdate = go Nothing
       let inc (Telegram.UpdateId n) = Telegram.UpdateId (n + 1)
           offset = fmap inc lastUpdateId
       res <-
-        (Right <$> Telegram.getUpdates
+        (Right <$> Telegram.getUpdatesAsValue
           (Telegram.GetUpdatesRequest offset Nothing (Just 25) Nothing))
         `catchError` (pure . Left)
 
@@ -150,19 +152,29 @@ startPolling handleUpdate = go Nothing
           liftIO (print servantErr)
           pure lastUpdateId
         Right result -> do
-          let updates = Telegram.responseResult result
+          let updateValues = Telegram.responseResult result
+              (errors, updates) = parseUpdates updateValues
               updateIds = map Telegram.updateUpdateId updates
               maxUpdateId = maximum (Nothing : map Just updateIds)
+          mapM_ reportParseError errors
           mapM_ handleUpdate updates
           pure maxUpdateId
       liftIO $ threadDelay 1000000
       go nextUpdateId
 
+    parseUpdates updates =
+      partitionEithers (map (parseEither parseJSON) updates)
+
+    reportParseError err =
+      liftIO $ putStrLn $
+        "Failed to parse an update! Please, make sure you have the latest version of `telegram-bot-api`\
+        \ library and consider opening an issue if so. Error message: " <> err
+
 -- ** Helpers
 
 -- | Instead of 'forkIO' which hides exceptions,
 -- allow users to handle those exceptions separately.
--- 
+--
 -- See <https://github.com/fizruk/telegram-bot-simple/issues/159>.
 asyncLink :: IO a -> IO (Async a)
 asyncLink action = do