Export resolver exceptions

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to
 ## [Unreleased]
 ### Added
 - `ToGraphQL` and `FromGraphQL` instances for `Word`.
+- `Resolver`: Export `ServerException`.
+- `Resolver.defaultResolver`: Throw `FieldNotResolvedException` if the requested
+  field is not in the parent object.
 
 ## [1.0.1.0] - 2023-02-17
 ### Added

cabal.project

@@ -1,4 +0,0 @@
-packages:
-  .
-
-constraints: graphql -json

graphql-spice.cabal

@@ -38,7 +38,7 @@ library
       containers ^>= 0.6.2,
       exceptions ^>= 0.10.4,
       hspec-expectations >= 0.8.2 && < 0.9,
-      graphql >= 1.0,
+      graphql >= 1.2,
       megaparsec >= 9.0 && < 10,
       scientific ^>= 0.3.7,
       text >= 1.2 && < 3,

src/Language/GraphQL/Resolver.hs

@@ -6,13 +6,14 @@
 
 -- | Helper functions and exceptions to write resolvers.
 module Language.GraphQL.Resolver
-    ( argument
+    ( ServerException(..)
+    , argument
     , defaultResolver
     ) where
 
 import Control.Monad.Catch (Exception(..), MonadCatch(..), MonadThrow(..))
 import Control.Monad.Trans.Reader (ReaderT, asks)
-import Data.HashMap.Strict ((!))
+import qualified Data.HashMap.Strict as HashMap
 import Data.Text (Text)
 import qualified Data.Text as Text
 import Data.Typeable (cast)
@@ -49,7 +50,8 @@ defaultResolver :: MonadCatch m => Name -> Type.Resolve m
 defaultResolver fieldName = do
     values' <- asks Type.values
     case values' of
-        Type.Object objectValue -> pure $ objectValue ! fieldName
+        Type.Object objectValue
+            | Just result <- HashMap.lookup fieldName objectValue -> pure result
         _nonObject -> throwM $ FieldNotResolvedException fieldName
 
 -- | Takes an argument name, validates that the argument exists, and optionally