Initial support for aliases in execute

Data/GraphQL/Execute.hs

@@ -11,6 +11,7 @@ import Data.Maybe (catMaybes)
 
 import qualified Data.Aeson as Aeson
 import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Text as T
 
 import Data.GraphQL.AST
 import Data.GraphQL.Schema (Resolver, Schema(..))
@@ -28,8 +29,10 @@ selectionSet :: Alternative f => Schema.Subs -> Resolver f -> SelectionSet -> f
 selectionSet f resolv = fmap (Aeson.Object . fold) . traverse (selection f resolv)
 
 selection :: Alternative f => Schema.Subs -> Resolver f -> Selection -> f Aeson.Object
-selection f resolv (SelectionField field@(Field _ name _ _ _)) =
+selection f resolv (SelectionField field@(Field alias name _ _ _)) =
-    fmap (HashMap.singleton name) $ Aeson.toJSON <$> resolv (fieldToInput f field)
+    fmap (HashMap.singleton aliasOrName) $ Aeson.toJSON <$> resolv (fieldToInput f field)
+  where
+    aliasOrName = if T.null alias then name else alias
 selection _ _ _ = empty
 
 -- * AST/Schema conversions

tests/Test/StarWars/QueryTests.hs

@@ -165,4 +165,34 @@ test = testGroup "Star Wars Query Tests"
     --         }
     --     |]
     --   $ object ["human" .= Aeson.Null]
+    , testCase "Luke with alias" . testQuery
+        [r| query FetchLukeAliased {
+              luke: human(id: "1000") {
+                name
+              }
+            }
+        |]
+      $ object [
+         "luke" .= object [
+           "name" .= ("Luke Skywalker" :: Text)
+           ]
+        ]
+    , testCase "Luke and Leia aliased" . testQuery
+        [r| query FetchLukeAndLeiaAliased {
+              luke: human(id: "1000") {
+                name
+              }
+              leia: human(id: "1003") {
+                name
+              }
+            }
+        |]
+      $ object [
+          "luke" .= object [
+            "name" .= ("Luke Skywalker" :: Text)
+           ]
+        , "leia" .= object [
+            "name" .= ("Leia Organa" :: Text)
+           ]
+        ]
   ]