Return correct type when an update_many has no arguments

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/10954
GitOrigin-RevId: 214163f4f4764ea66194bf26bfe202a807771e90

server/lib/api-tests/src/Test/Mutations/Insert/MultipleSpec.hs

@@ -121,6 +121,7 @@ tests = do
                     }
                   ]
                 ) {
+                  affected_rows
                   returning {
                     id
                     title
@@ -134,6 +135,7 @@ tests = do
           [interpolateYaml|
             data:
               insert_#{schemaName}_article:
+                affected_rows: 2
                 returning:
                   - id: 1
                     title: "Article 1"
@@ -156,6 +158,7 @@ tests = do
                 insert_#{schemaName}_article(
                   objects: []
                 ) {
+                  affected_rows
                   returning {
                     id
                     title
@@ -169,6 +172,7 @@ tests = do
           [interpolateYaml|
             data:
               insert_#{schemaName}_article:
+                affected_rows: 0
                 returning: []
           |]
 

server/lib/api-tests/src/Test/Mutations/MultiplePerRequest/UpdateManySpec.hs

@@ -69,6 +69,29 @@ schema =
 tests :: SpecWith TestEnvironment
 tests = do
   describe "Update many objects" do
+    it "When no updates are provided" \testEnvironment -> do
+      let expected :: Value
+          expected =
+            [yaml|
+              data:
+                update_hasura_author_many: []
+            |]
+
+          actual :: IO Value
+          actual =
+            postGraphql
+              testEnvironment
+              [graphql|
+                mutation {
+                  update_hasura_author_many(
+                    updates: []
+                  ) {
+                    affected_rows
+                  }
+                }
+              |]
+
+      shouldReturnYaml testEnvironment actual expected
     it "When many equals zero" \testEnvironment -> do
       let expected :: Value
           expected =

server/src-lib/Hasura/Backends/Postgres/Instances/Execute.hs

@@ -45,7 +45,7 @@ import Hasura.Backends.Postgres.Translate.Select qualified as DS
 import Hasura.Backends.Postgres.Types.Function qualified as Postgres
 import Hasura.Backends.Postgres.Types.Update qualified as Postgres
 import Hasura.Base.Error (QErr)
-import Hasura.EncJSON (EncJSON, encJFromJValue)
+import Hasura.EncJSON (EncJSON, encJFromJValue, encJFromList)
 import Hasura.Function.Cache
 import Hasura.GraphQL.Execute.Backend
   ( BackendExecute (..),
@@ -307,7 +307,9 @@ convertUpdate sourceName modelSourceType env manager logger userInfo updateOpera
       pure $ concat whereModelsList
   let modelNames = [ModelNameInfo (modelName, modelType, sourceName, modelSourceType)] <> (argModelNames) <> preUpdatePermissionModelNames <> postUpdateCheckModelNames <> (returnModels)
   if Postgres.updateVariantIsEmpty $ IR._auUpdateVariant updateOperation
-    then pure $ (OnBaseMonad $ pure $ IR.buildEmptyMutResp $ IR._auOutput preparedUpdate, modelNames)
+    then case mutationUpdateVariant of
+      Postgres.SingleBatch _ -> pure $ (OnBaseMonad $ pure $ IR.buildEmptyMutResp (IR._auOutput preparedUpdate), modelNames)
+      Postgres.MultipleBatches _ -> pure (OnBaseMonad $ pure (encJFromList []), modelNames)
     else
       pure
         $ ( OnBaseMonad