diff options
Diffstat (limited to 'src/Data/GraphQL/Schema.hs')
| -rw-r--r-- | src/Data/GraphQL/Schema.hs | 91 |
1 files changed, 52 insertions, 39 deletions
diff --git a/src/Data/GraphQL/Schema.hs b/src/Data/GraphQL/Schema.hs index 919235e..ad47cef 100644 --- a/src/Data/GraphQL/Schema.hs +++ b/src/Data/GraphQL/Schema.hs @@ -6,16 +6,16 @@ module Data.GraphQL.Schema ( Schema , Resolver , Subs + , nullableArray + , nullableEnum + , nullableObject + , nullableScalar , object - , object' , objectA - , objectA' , scalar , scalarA , array - , array' , arrayA - , arrayA' , enum , enumA , resolve @@ -68,18 +68,16 @@ objectA :: MonadPlus m => Name -> (Arguments -> ActionT m [Resolver m]) -> Resolver m objectA name f = Resolver name $ resolveFieldValue f resolveRight where - resolveRight fld@(Field _ _ _ flds) resolver = withField name (resolve resolver flds) fld + resolveRight fld@(Field _ _ _ flds) resolver = withField (resolve resolver flds) fld --- | Create a named 'Resolver' from a list of 'Resolver's. -object' :: MonadPlus m => Name -> ActionT m [Resolver m] -> Resolver m -object' name = objectA' name . const - --- | Like 'object'' but also taking 'Argument's. -objectA' :: MonadPlus m - => Name -> (Arguments -> ActionT m [Resolver m]) -> Resolver m -objectA' name f = Resolver name $ resolveFieldValue f resolveRight +-- | Like 'object' but can be null. +nullableObject :: MonadPlus m + => Name -> (Arguments -> ActionT m (Maybe [Resolver m])) -> Resolver m +nullableObject name f = Resolver name $ resolveFieldValue f resolveRight where - resolveRight fld@(Field _ _ _ flds) resolver = withField name (resolve resolver flds) fld + resolveRight fld@(Field _ _ _ flds) (Just resolver) = withField (resolve resolver flds) fld + resolveRight fld Nothing + = return $ HashMap.singleton (aliasOrName fld) Aeson.Null -- | A scalar represents a primitive value, like a string or an integer. scalar :: (MonadPlus m, Aeson.ToJSON a) => Name -> ActionT m a -> Resolver m @@ -90,9 +88,20 @@ scalarA :: (MonadPlus m, Aeson.ToJSON a) => Name -> (Arguments -> ActionT m a) -> Resolver m scalarA name f = Resolver name $ resolveFieldValue f resolveRight where - resolveRight fld@(Field _ _ _ []) result = withField name (return result) fld + resolveRight fld@(Field _ _ _ []) result = withField (return result) fld resolveRight _ _ = mzero +-- | Lika 'scalar' but can be null. +nullableScalar :: (MonadPlus m, Aeson.ToJSON a) + => Name -> (Arguments -> ActionT m (Maybe a)) -> Resolver m +nullableScalar name f = Resolver name $ resolveFieldValue f resolveRight + where + resolveRight fld@(Field _ _ _ []) (Just result) = withField (return result) fld + resolveRight fld Nothing + = return $ HashMap.singleton (aliasOrName fld) Aeson.Null + resolveRight _ _ = mzero + +-- | Creates a list of 'Resolver's. array :: MonadPlus m => Name -> ActionT m [[Resolver m]] -> Resolver m array name = arrayA name . const @@ -102,19 +111,17 @@ arrayA :: MonadPlus m arrayA name f = Resolver name $ resolveFieldValue f resolveRight where resolveRight fld@(Field _ _ _ sels) resolver - = withField name (traverse (`resolve` sels) resolver) fld - --- | Like 'object'' but taking lists of 'Resolver's instead of a single list. -array' :: MonadPlus m => Name -> ActionT m [[Resolver m]] -> Resolver m -array' name = arrayA' name . const + = withField (traverse (`resolve` sels) resolver) fld --- | Like 'array'' but also taking 'Argument's. -arrayA' :: MonadPlus m - => Name -> (Arguments -> ActionT m [[Resolver m]]) -> Resolver m -arrayA' name f = Resolver name $ resolveFieldValue f resolveRight +-- | Like 'array' but can be null. +nullableArray :: MonadPlus m + => Name -> (Arguments -> ActionT m (Maybe [[Resolver m]])) -> Resolver m +nullableArray name f = Resolver name $ resolveFieldValue f resolveRight where - resolveRight fld@(Field _ _ _ sels) resolver - = withField name (traverse (`resolve` sels) resolver) fld + resolveRight fld@(Field _ _ _ sels) (Just resolver) + = withField (traverse (`resolve` sels) resolver) fld + resolveRight fld Nothing + = return $ HashMap.singleton (aliasOrName fld) Aeson.Null -- | Represents one of a finite set of possible values. -- Used in place of a 'scalar' when the possible responses are easily enumerable. @@ -125,7 +132,16 @@ enum name = enumA name . const enumA :: MonadPlus m => Name -> (Arguments -> ActionT m [Text]) -> Resolver m enumA name f = Resolver name $ resolveFieldValue f resolveRight where - resolveRight fld resolver = withField name (return resolver) fld + resolveRight fld resolver = withField (return resolver) fld + +-- | Like 'array'' but also taking 'Argument's. +nullableEnum :: MonadPlus m + => Name -> (Arguments -> ActionT m (Maybe [Text])) -> Resolver m +nullableEnum name f = Resolver name $ resolveFieldValue f resolveRight + where + resolveRight fld (Just resolver) = withField (return resolver) fld + resolveRight fld Nothing + = return $ HashMap.singleton (aliasOrName fld) Aeson.Null resolveFieldValue :: MonadPlus m => ([Argument] -> ActionT m a) @@ -138,17 +154,13 @@ resolveFieldValue f resolveRight fld@(Field alias name args _) = do where resolveLeft err = do _ <- addErrMsg err - return $ HashMap.singleton (fromMaybe name alias) Aeson.Null + return $ HashMap.singleton (aliasOrName fld) Aeson.Null -- | Helper function to facilitate 'Argument' handling. withField :: (MonadPlus m, Aeson.ToJSON a) - => Name -> CollectErrsT m a -> Field -> CollectErrsT m (HashMap Text Aeson.Value) -withField name v (Field alias _ _ _) - = HashMap.singleton aliasOrName . Aeson.toJSON <$> runAppendErrs v - {- TODO: Report error when Non-Nullable type for field argument. - else return (HashMap.singleton aliasOrName Aeson.Null) -} - where - aliasOrName = fromMaybe name alias + => CollectErrsT m a -> Field -> CollectErrsT m (HashMap Text Aeson.Value) +withField v fld + = HashMap.singleton (aliasOrName fld) . Aeson.toJSON <$> runAppendErrs v -- | Takes a list of 'Resolver's and a list of 'Field's and applies each -- 'Resolver' to each 'Field'. Resolves into a value containing the @@ -160,8 +172,9 @@ resolve resolvers = fmap (Aeson.toJSON . fold) . traverse tryResolvers tryResolvers fld = mplus (maybe mzero (tryResolver fld) $ find (compareResolvers fld) resolvers) $ errmsg fld compareResolvers (Field _ name _ _) (Resolver name' _) = name == name' tryResolver fld (Resolver _ resolver) = resolver fld - errmsg (Field alias name _ _) = do + errmsg fld@(Field alias name _ _) = do addErrMsg $ T.unwords ["field", name, "not resolved."] - return $ HashMap.singleton aliasOrName Aeson.Null - where - aliasOrName = fromMaybe name alias + return $ HashMap.singleton (aliasOrName fld) Aeson.Null + +aliasOrName :: Field -> Text +aliasOrName (Field alias name _ _) = fromMaybe name alias |