Add location information to the intermediate tree

src/Language/GraphQL/Execute/Execution.hs

@@ -13,6 +13,7 @@ import Control.Monad.Trans.Class (lift)
 import Control.Monad.Trans.Reader (runReaderT)
 import Control.Monad.Trans.State (gets)
 import Data.List.NonEmpty (NonEmpty(..))
+import qualified Data.List.NonEmpty as NonEmpty
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
 import Data.Maybe (fromMaybe)
@@ -66,7 +67,7 @@ collectFields objectType = foldl forEach OrderedMap.empty
         | otherwise = groupedFields
 
 aliasOrName :: forall m. Transform.Field m -> Name
-aliasOrName (Transform.Field alias name _ _) = fromMaybe name alias
+aliasOrName (Transform.Field alias name _ _ _) = fromMaybe name alias
 
 resolveAbstractType :: Monad m
     => Internal.AbstractType m
@@ -96,7 +97,7 @@ executeField fieldResolver prev fields
   where
     executeField' fieldDefinition resolver = do
         let Out.Field _ fieldType argumentDefinitions = fieldDefinition
-        let (Transform.Field _ _ arguments' _ :| []) = fields
+        let (Transform.Field _ _ arguments' _ _ :| []) = fields
         case coerceArgumentValues argumentDefinitions arguments' of
             Nothing -> addError null $ Error "Argument coercing failed." [] []
             Just argumentValues -> do
@@ -120,11 +121,12 @@ completeValue outputType@(Out.ScalarBaseType _) _ (Type.Float float) =
     coerceResult outputType $ Float float
 completeValue outputType@(Out.ScalarBaseType _) _ (Type.String string) =
     coerceResult outputType $ String string
-completeValue outputType@(Out.EnumBaseType enumType) _ (Type.Enum enum) =
+completeValue outputType@(Out.EnumBaseType enumType) fields (Type.Enum enum) =
     let Type.EnumType _ _ enumMembers = enumType
+        Transform.Field _ _ _ _ location = NonEmpty.head fields
      in if HashMap.member enum enumMembers
         then coerceResult outputType $ Enum enum
-        else addError null $ Error "Enum value completion failed." [] []
+        else addError null $ Error "Enum value completion failed." [location] []
 completeValue (Out.ObjectBaseType objectType) fields result =
     executeSelectionSet result objectType $ mergeSelectionSets fields
 completeValue (Out.InterfaceBaseType interfaceType) fields result
@@ -139,12 +141,13 @@ completeValue (Out.InterfaceBaseType interfaceType) fields result
 completeValue (Out.UnionBaseType unionType) fields result
     | Type.Object objectMap <- result = do
         let abstractType = Internal.AbstractUnionType unionType
+        let Transform.Field _ _ _ _ location = NonEmpty.head fields
         concreteType <- resolveAbstractType abstractType objectMap
         case concreteType of
             Just objectType -> executeSelectionSet result objectType
                 $ mergeSelectionSets fields
             Nothing -> addError null
-                $ Error "Union value completion failed." [] []
+                $ Error "Union value completion failed." [location] []
 completeValue _ _ _ = addError null $ Error "Value completion failed." [] []
 
 mergeSelectionSets :: MonadCatch m
@@ -152,7 +155,7 @@ mergeSelectionSets :: MonadCatch m
     -> Seq (Transform.Selection m)
 mergeSelectionSets = foldr forEach mempty
   where
-    forEach (Transform.Field _ _ _ fieldSelectionSet) selectionSet =
+    forEach (Transform.Field _ _ _ fieldSelectionSet _) selectionSet =
         selectionSet <> fieldSelectionSet
 
 coerceResult :: (MonadCatch m, Serialize a)
@@ -177,7 +180,7 @@ executeSelectionSet result objectType@(Out.ObjectType _ _ _ resolvers) selection
     coerceResult (Out.NonNullObjectType objectType) $ Object resolvedValues
   where
     forEach fields@(field :| _) =
-        let Transform.Field _ name _ _ = field
+        let Transform.Field _ name _ _ _ = field
          in traverse (tryResolver fields) $ lookupResolver name
     lookupResolver = flip HashMap.lookup resolvers
     tryResolver fields resolver =

src/Language/GraphQL/Execute/Subscribe.hs

@@ -52,7 +52,7 @@ createSourceEventStream :: MonadCatch m
     -> m (Either String (Out.SourceEventStream m))
 createSourceEventStream _types subscriptionType@(Out.ObjectType _ _ _ fieldTypes) fields
     | [fieldGroup] <- OrderedMap.elems groupedFieldSet
-    , Transform.Field _ fieldName arguments' _ <- NonEmpty.head fieldGroup
+    , Transform.Field _ fieldName arguments' _ _ <- NonEmpty.head fieldGroup
     , resolverT <- fieldTypes HashMap.! fieldName
     , Out.EventStreamResolver fieldDefinition _ resolver <- resolverT
     , Out.Field _ _fieldType argumentDefinitions <- fieldDefinition =

src/Language/GraphQL/Execute/Transform.hs

@@ -1,3 +1,7 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -77,7 +81,11 @@ data Operation m
 
 -- | Single GraphQL field.
 data Field m = Field
-    (Maybe Full.Name) Full.Name (HashMap Full.Name Input) (Seq (Selection m))
+    (Maybe Full.Name)
+    Full.Name
+    (HashMap Full.Name Input)
+    (Seq (Selection m))
+    Full.Location
 
 -- | Contains the operation to be executed along with its root type.
 data Document m = Document
@@ -263,11 +271,11 @@ selection (Full.InlineFragmentSelection fragmentSelection) =
     inlineFragment fragmentSelection
 
 field :: Full.Field ->  State (Replacement m) (Maybe (Field m))
-field (Full.Field alias name arguments' directives' selections _) = do
+field (Full.Field alias name arguments' directives' selections location) = do
     fieldArguments <- foldM go HashMap.empty arguments'
     fieldSelections <- appendSelection selections
     fieldDirectives <- Definition.selection <$> directives directives'
-    let field' = Field alias name fieldArguments fieldSelections
+    let field' = Field alias name fieldArguments fieldSelections location
     pure $ field' <$ fieldDirectives
   where
     go arguments (Full.Argument name' (Full.Node value' _) _) =

tests/Language/GraphQL/ExecuteSpec.hs

@@ -15,7 +15,7 @@ import Data.Aeson.Types (emptyObject)
 import Data.Conduit
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
-import Language.GraphQL.AST (Document, Name)
+import Language.GraphQL.AST (Document, Location(..), Name)
 import Language.GraphQL.AST.Parser (document)
 import Language.GraphQL.Error
 import Language.GraphQL.Execute
@@ -37,6 +37,29 @@ queryType = Out.ObjectType "Query" Nothing []
     philosopherField =
         Out.Field Nothing (Out.NonNullObjectType philosopherType) HashMap.empty
 
+musicType :: Out.ObjectType (Either SomeException)
+musicType = Out.ObjectType "Music" Nothing []
+    $ HashMap.fromList resolvers
+  where
+    resolvers =
+        [ ("instrument", ValueResolver instrumentField instrumentResolver)
+        ]
+    instrumentResolver = pure $ Type.String "piano"
+    instrumentField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+
+poetryType :: Out.ObjectType (Either SomeException)
+poetryType = Out.ObjectType "Poetry" Nothing []
+    $ HashMap.fromList resolvers
+  where
+    resolvers =
+        [ ("genre", ValueResolver genreField genreResolver)
+        ]
+    genreResolver = pure $ Type.String "Futurism"
+    genreField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+
+interestType :: Out.UnionType (Either SomeException)
+interestType = Out.UnionType "Interest" Nothing [musicType, poetryType]
+
 philosopherType :: Out.ObjectType (Either SomeException)
 philosopherType = Out.ObjectType "Philosopher" Nothing []
     $ HashMap.fromList resolvers
@@ -45,6 +68,7 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
         [ ("firstName", ValueResolver firstNameField firstNameResolver)
         , ("lastName", ValueResolver lastNameField lastNameResolver)
         , ("school", ValueResolver schoolField schoolResolver)
+        , ("interest", ValueResolver interestField interestResolver)
         ]
     firstNameField =
         Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
@@ -55,6 +79,11 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
     schoolField
        = Out.Field Nothing (Out.NonNullEnumType schoolType) HashMap.empty
     schoolResolver = pure $ Type.Enum "EXISTENTIALISM"
+    interestField
+        = Out.Field Nothing (Out.NonNullUnionType interestType) HashMap.empty
+    interestResolver = pure
+        $ Type.Object
+        $ HashMap.fromList [("instrument", "piano")]
 
 subscriptionType :: Out.ObjectType (Either SomeException)
 subscriptionType = Out.ObjectType "Subscription" Nothing []
@@ -138,7 +167,7 @@ spec =
                         ]
                     executionErrors = pure $ Error
                         { message = "Enum value completion failed."
-                        , locations = []
+                        , locations = [Location 1 17]
                         , path = []
                         }
                     expected = Response data'' executionErrors
@@ -146,6 +175,22 @@ spec =
                         $ parse document "" "{ philosopher { school } }"
                 in actual `shouldBe` expected
 
+            it "gives location information for invalid interfaces" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.object
+                            [ "interest" .= Aeson.Null
+                            ]
+                        ]
+                    executionErrors = pure $ Error
+                        { message = "Union value completion failed."
+                        , locations = [Location 1 17]
+                        , path = []
+                        }
+                    expected = Response data'' executionErrors
+                    Right (Right actual) = either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher { interest } }"
+                in actual `shouldBe` expected
+
         context "Subscription" $
             it "subscribes" $
                 let data'' = Aeson.object