haddocks

Web/Scotty.hs

@@ -255,23 +255,24 @@ queryParam = Trans.queryParam
 
 -- | Look up a capture parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions. In particular, route pattern matching will not continue, so developers
+-- must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 captureParamMaybe :: (Trans.Parsable a) => Text -> ActionM (Maybe a)
 captureParamMaybe = Trans.captureParamMaybe
 
 -- | Look up a form parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions, so developers must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 formParamMaybe :: (Trans.Parsable a) => Text -> ActionM (Maybe a)
 formParamMaybe = Trans.formParamMaybe
 
 -- | Look up a query parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions, so developers must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 queryParamMaybe :: (Trans.Parsable a) => Text -> ActionM (Maybe a)

Web/Scotty/Action.hs

@@ -315,23 +315,24 @@ queryParam = paramWith QueryParam envQueryParams status400
 
 -- | Look up a capture parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions. In particular, route pattern matching will not continue, so developers
+-- must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 captureParamMaybe :: (Parsable a, Monad m) => T.Text -> ActionT m (Maybe a)
 captureParamMaybe = paramWithMaybe envCaptureParams
 
 -- | Look up a form parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions, so developers must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 formParamMaybe :: (Parsable a, Monad m) => T.Text -> ActionT m (Maybe a)
 formParamMaybe = paramWithMaybe envFormParams
 
 -- | Look up a query parameter. Returns 'Nothing' if the parameter is not found or cannot be parsed at the right type.
 --
--- NB : Doesn't throw exceptions.
+-- NB : Doesn't throw exceptions, so developers must 'raiseStatus' or 'throw' to signal something went wrong.
 --
 -- /Since: FIXME/
 queryParamMaybe :: (Parsable a, Monad m) => T.Text -> ActionT m (Maybe a)

test/Web/ScottySpec.hs

@@ -238,15 +238,22 @@ spec = do
     describe "captureParamMaybe" $ do
       withApp (
         do
-          Scotty.get "/search/:q" $ do
+          Scotty.get "/a/:q" $ do
+            mx <- captureParamMaybe "q"
+            case mx of
+              Just (_ :: Int) -> status status500
+              Nothing -> status status200
+          Scotty.get "/b/:q" $ do
             mx <- captureParamMaybe "z"
             case mx of
-              Just (_ :: TL.Text) -> status status500
+              Just (_ :: TL.Text) -> text "impossible" >> status status500
               Nothing -> status status200
               ) $ do
+        it "responds with 200 OK if the parameter cannot be parsed at the right type, 500 otherwise" $ do
+          get "/a/potato" `shouldRespondWith` 200
+          get "/a/42" `shouldRespondWith` 500
         it "responds with 200 OK if the parameter is not found" $ do
-          -- get "/search/42" `shouldRespondWith` 200 { matchBody = "int" }
-          get "/search/potato" `shouldRespondWith` 200
+          get "/b/potato" `shouldRespondWith` 200
 
 
     describe "text" $ do