server: null forwarding feature flag

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9861
Co-authored-by: paritosh-08 <85472423+paritosh-08@users.noreply.github.com>
Co-authored-by: Rob Dominguez <24390149+robertjdominguez@users.noreply.github.com>
GitOrigin-RevId: 46153d68adf1acc707dc451555055600b006629e

docs/docs/deployment/graphql-engine-flags/reference.mdx

@@ -113,8 +113,8 @@ When you use [webhook or JWT mode for authentication](/auth/authentication/index
 
 ### Admin Secrets
 
-A list of valid admin [secret keys](/auth/authentication/multiple-admin-secrets.mdx) any one of which can be used to access the
-Hasura instance.
+A list of valid admin [secret keys](/auth/authentication/multiple-admin-secrets.mdx) any one of which can be used to
+access the Hasura instance.
 
 |                     |                                |
 | ------------------- | ------------------------------ |
@@ -344,13 +344,13 @@ subgraph in an Apollo supergraph.
 
 Sets the maximum cumulative length of all headers in bytes.
 
-|                     |                                           |
-| ------------------- | ----------------------------------------- |
-| **Flag**            | `--max-total-header-length`               |
-| **Env var**         | `HASURA_GRAPHQL_MAX_TOTAL_HEADER_LENGTH`  |
-| **Accepted values** | Integer                                   |
-| **Default**         | `1024*1024` (1MB)                         |
-| **Supported in**    | CE, Enterprise Edition                    |
+|                     |                                          |
+| ------------------- | ---------------------------------------- |
+| **Flag**            | `--max-total-header-length`              |
+| **Env var**         | `HASURA_GRAPHQL_MAX_TOTAL_HEADER_LENGTH` |
+| **Accepted values** | Integer                                  |
+| **Default**         | `1024*1024` (1MB)                        |
+| **Supported in**    | CE, Enterprise Edition                   |
 
 ### Enable Console
 
@@ -367,8 +367,9 @@ Enable the Hasura Console (served by the server on `/` and `/console`).
 
 ### Enable High-cardinality Labels for Metrics
 
-Enable high-cardinality labels for [Prometheus Metrics](/observability/enterprise-edition/prometheus/metrics.mdx). Enabling this setting
-will add more labels to some of the metrics (e.g. `operation_name` label for Graphql subscription metrics).
+Enable high-cardinality labels for [Prometheus Metrics](/observability/enterprise-edition/prometheus/metrics.mdx).
+Enabling this setting will add more labels to some of the metrics (e.g. `operation_name` label for Graphql subscription
+metrics).
 
 |                     |                                                         |
 | ------------------- | ------------------------------------------------------- |
@@ -804,7 +805,8 @@ The maximum number of query plans that can be cached, where `0` disables the cac
 
 ### Rate-Limit Redis TLS Hostname
 
-The hostname to use for SNI when connecting to a rate-limiting [Redis instance over TLS](/caching/enterprise-caching.mdx).
+The hostname to use for SNI when connecting to a rate-limiting
+[Redis instance over TLS](/caching/enterprise-caching.mdx).
 
 |                     |                                                |
 | ------------------- | ---------------------------------------------- |
@@ -885,8 +887,8 @@ The path to a shared CA store to use to connect to both (caching and rate-limiti
 
 ### Redis URL
 
-The Redis URL to use for [query caching](/caching/enterprise-caching.mdx) and [Webhook Auth
-Caching](/auth/authentication/webhook.mdx#webhook-auth-caching).
+The Redis URL to use for [query caching](/caching/enterprise-caching.mdx) and
+[Webhook Auth Caching](/auth/authentication/webhook.mdx#webhook-auth-caching).
 
 |                     |                                          |
 | ------------------- | ---------------------------------------- |
@@ -946,6 +948,39 @@ List of third-party identity providers to enable Single Sign-on authentication f
 | **Example**         | `[{\"client_id\": \"<client-id-from-idp>\", \"name\": \"<display-name>\", \"scope\": \"openid\", \"authorization_url\": \"<login-url>\", \"request_token_url\": \"<request-token-url>\", \"admin_roles\": [\"admin\"], \"jwt_secret\": {\"type\": \"RS256\", \"jwk_url\": \"https://...\", \"issuer\": \"myapp\"}}]` |
 | **Supported in**    | EE                                                                                                                                                                                                                                                                                                                   |
 
+### Skip Arguments with `null` Values for Remote Schema
+
+Skip arguments with `null` values while resolving fields from Remote Schemas. For instance:
+
+```graphql
+query RemoteQuery {
+  users(type:null) {
+    id
+    ...
+  }
+}
+```
+
+is forwarded as:
+
+```graphql
+query RemoteQuery {
+  users {
+    id
+    ...
+  }
+}
+```
+
+|                     |                                           |
+| ------------------- | ----------------------------------------- |
+| **Flag**            | `--remote-schema-skip-nulls`              |
+| **Env var**         | `HASURA_GRAPHQL_REMOTE_SCHEMA_SKIP_NULLS` |
+| **Accepted values** | Boolean                                   |
+| **Options**         | `true` or `false`                         |
+| **Default**         | `false`                                   |
+| **Supported in**    | CE, Enterprise Edition, Cloud             |
+
 ### Streaming Queries Multiplexed Batch Size
 
 Multiplexed [streaming queries](/subscriptions/postgres/streaming/index.mdx) are split into batches of the specified

server/lib/test-harness/src/Harness/Constants.hs

@@ -280,6 +280,7 @@ serveOptions =
       soEnableTelemetry = Init.TelemetryDisabled,
       soStringifyNum = Options.Don'tStringifyNumbers,
       soDangerousBooleanCollapse = Options.Don'tDangerouslyCollapseBooleans,
+      soRemoteNullForwardingPolicy = Options.RemoteForwardAccurately,
       soEnabledAPIs = testSuiteEnabledApis,
       soLiveQueryOpts = ES.mkSubscriptionsOptions Nothing Nothing,
       soStreamingQueryOpts = ES.mkSubscriptionsOptions Nothing Nothing,

server/src-lib/Hasura/App.hs

@@ -502,7 +502,7 @@ initialiseAppContext env serveOptions@ServeOptions {..} AppInit {..} = do
   appEnv@AppEnv {..} <- askAppEnv
   let cacheStaticConfig = buildCacheStaticConfig appEnv
       Loggers _ logger pgLogger = appEnvLoggers
-      sqlGenCtx = initSQLGenCtx soExperimentalFeatures soStringifyNum soDangerousBooleanCollapse
+      sqlGenCtx = initSQLGenCtx soExperimentalFeatures soStringifyNum soDangerousBooleanCollapse soRemoteNullForwardingPolicy
       cacheDynamicConfig =
         CacheDynamicConfig
           soInferFunctionPermissions

server/src-lib/Hasura/App/State.hs

@@ -247,7 +247,7 @@ buildAppContextRule ::
   (ServeOptions impl, E.Environment, InvalidationKeys) `arr` AppContext
 buildAppContextRule = proc (ServeOptions {..}, env, _keys) -> do
   authMode <- buildAuthMode -< (soAdminSecret, soAuthHook, soJwtSecret, soUnAuthRole)
-  sqlGenCtx <- buildSqlGenCtx -< (soExperimentalFeatures, soStringifyNum, soDangerousBooleanCollapse)
+  let sqlGenCtx = initSQLGenCtx soExperimentalFeatures soStringifyNum soDangerousBooleanCollapse soRemoteNullForwardingPolicy
   responseInternalErrorsConfig <- buildResponseInternalErrorsConfig -< (soAdminInternalErrors, soDevMode)
   eventEngineCtx <- buildEventEngineCtx -< (soEventsHttpPoolSize, soEventsFetchInterval, soEventsFetchBatchSize)
   returnA
@@ -275,10 +275,6 @@ buildAppContextRule = proc (ServeOptions {..}, env, _keys) -> do
           acCloseWebsocketsOnMetadataChangeStatus = soCloseWebsocketsOnMetadataChangeStatus
         }
   where
-    buildSqlGenCtx = Inc.cache proc (experimentalFeatures, stringifyNum, dangerousBooleanCollapse) -> do
-      let sqlGenCtx = initSQLGenCtx experimentalFeatures stringifyNum dangerousBooleanCollapse
-      returnA -< sqlGenCtx
-
     buildEventEngineCtx = Inc.cache proc (httpPoolSize, fetchInterval, fetchBatchSize) -> do
       eventEngineCtx <- bindA -< initEventEngineCtx httpPoolSize fetchInterval fetchBatchSize
       returnA -< eventEngineCtx
@@ -313,8 +309,8 @@ buildAppContextRule = proc (ServeOptions {..}, env, _keys) -> do
 --------------------------------------------------------------------------------
 -- subsets
 
-initSQLGenCtx :: HashSet ExperimentalFeature -> Options.StringifyNumbers -> Options.DangerouslyCollapseBooleans -> SQLGenCtx
-initSQLGenCtx experimentalFeatures stringifyNum dangerousBooleanCollapse =
+initSQLGenCtx :: HashSet ExperimentalFeature -> Options.StringifyNumbers -> Options.DangerouslyCollapseBooleans -> Options.RemoteNullForwardingPolicy -> SQLGenCtx
+initSQLGenCtx experimentalFeatures stringifyNum dangerousBooleanCollapse remoteNullForwardingPolicy =
   let optimizePermissionFilters
         | EFOptimizePermissionFilters `elem` experimentalFeatures = Options.OptimizePermissionFilters
         | otherwise = Options.Don'tOptimizePermissionFilters
@@ -322,7 +318,7 @@ initSQLGenCtx experimentalFeatures stringifyNum dangerousBooleanCollapse =
       bigqueryStringNumericInput
         | EFBigQueryStringNumericInput `elem` experimentalFeatures = Options.EnableBigQueryStringNumericInput
         | otherwise = Options.DisableBigQueryStringNumericInput
-   in SQLGenCtx stringifyNum dangerousBooleanCollapse optimizePermissionFilters bigqueryStringNumericInput
+   in SQLGenCtx stringifyNum dangerousBooleanCollapse remoteNullForwardingPolicy optimizePermissionFilters bigqueryStringNumericInput
 
 buildCacheStaticConfig :: AppEnv -> CacheStaticConfig
 buildCacheStaticConfig AppEnv {..} =

server/src-lib/Hasura/GraphQL/RemoteServer.hs

@@ -34,6 +34,7 @@ import Hasura.Prelude
 import Hasura.RQL.DDL.Headers (makeHeadersFromConf)
 import Hasura.RQL.Types.Common
 import Hasura.RQL.Types.Roles (adminRoleName)
+import Hasura.RQL.Types.Schema.Options qualified as Options
 import Hasura.RemoteSchema.Metadata
 import Hasura.RemoteSchema.SchemaCache.Types
 import Hasura.Server.Utils
@@ -93,7 +94,7 @@ stitchRemoteSchema rawIntrospectionResult rsDef@ValidatedRemoteSchemaDef {..} =
   -- quickly reject an invalid schema.
   void
     $ runMemoizeT
-    $ runRemoteSchema minimumValidContext
+    $ runRemoteSchema minimumValidContext Options.RemoteForwardAccurately
     $ buildRemoteParser @_ @_ @Parse
       _rscIntroOriginal
       mempty -- remote relationships

server/src-lib/Hasura/GraphQL/Schema.hs

@@ -244,13 +244,14 @@ buildSchemaOptions ::
   HashSet ExperimentalFeature ->
   SchemaOptions
 buildSchemaOptions
-  ( SQLGenCtx stringifyNum dangerousBooleanCollapse optimizePermissionFilters bigqueryStringNumericInput,
+  ( SQLGenCtx stringifyNum dangerousBooleanCollapse remoteNullForwardingPolicy optimizePermissionFilters bigqueryStringNumericInput,
     functionPermsCtx
     )
   expFeatures =
     SchemaOptions
       { soStringifyNumbers = stringifyNum,
         soDangerousBooleanCollapse = dangerousBooleanCollapse,
+        soRemoteNullForwardingPolicy = remoteNullForwardingPolicy,
         soInferFunctionPermissions = functionPermsCtx,
         soOptimizePermissionFilters = optimizePermissionFilters,
         soIncludeUpdateManyFields =
@@ -315,7 +316,7 @@ buildRoleContext options sources remotes actions customTypes role remoteSchemaPe
     -- build all remote schemas
     -- we only keep the ones that don't result in a name conflict
     (remoteSchemaFields, !remoteSchemaErrors) <-
-      runRemoteSchema schemaContext
+      runRemoteSchema schemaContext (soRemoteNullForwardingPolicy schemaOptions)
         $ buildAndValidateRemoteSchemas remotes sourcesQueryFields sourcesMutationBackendFields role remoteSchemaPermsCtx
     let remotesQueryFields = concatMap piQuery remoteSchemaFields
         remotesMutationFields = concat $ mapMaybe piMutation remoteSchemaFields
@@ -610,7 +611,7 @@ unauthenticatedContext options sources allRemotes expFeatures remoteSchemaPermsC
       Options.DisableRemoteSchemaPermissions -> do
         -- Permissions are disabled, unauthenticated users have access to remote schemas.
         (remoteFields, remoteSchemaErrors) <-
-          runRemoteSchema fakeSchemaContext
+          runRemoteSchema fakeSchemaContext (soRemoteNullForwardingPolicy schemaOptions)
             $ buildAndValidateRemoteSchemas allRemotes [] [] fakeRole remoteSchemaPermsCtx
         pure
           ( fmap (fmap RFRemote) <$> concatMap piQuery remoteFields,
@@ -650,6 +651,7 @@ buildAndValidateRemoteSchemas ::
   Options.RemoteSchemaPermissions ->
   SchemaT
     ( SchemaContext,
+      Options.RemoteNullForwardingPolicy,
       MkTypename,
       CustomizeRemoteFieldName
     )
@@ -707,6 +709,7 @@ buildRemoteSchemaParser ::
   RemoteSchemaCtx ->
   SchemaT
     ( SchemaContext,
+      Options.RemoteNullForwardingPolicy,
       MkTypename,
       CustomizeRemoteFieldName
     )

server/src-lib/Hasura/GraphQL/Schema/Common.hs

@@ -261,6 +261,7 @@ runSourceSchema context options sourceInfo (SchemaT action) = runReaderT action
 type MonadBuildRemoteSchema r m n =
   ( MonadBuildSchemaBase m n,
     Has SchemaContext r,
+    Has Options.RemoteNullForwardingPolicy r,
     Has CustomizeRemoteFieldName r,
     Has MkTypename r
   )
@@ -268,15 +269,17 @@ type MonadBuildRemoteSchema r m n =
 -- | Runs a schema-building computation with all the context required to build a remote schema.
 runRemoteSchema ::
   SchemaContext ->
+  Options.RemoteNullForwardingPolicy ->
   SchemaT
     ( SchemaContext,
+      Options.RemoteNullForwardingPolicy,
       MkTypename,
       CustomizeRemoteFieldName
     )
     m
     a ->
   m a
-runRemoteSchema context (SchemaT action) = runReaderT action (context, mempty, mempty)
+runRemoteSchema context nullForwarding (SchemaT action) = runReaderT action (context, nullForwarding, mempty, mempty)
 
 type MonadBuildActionSchema r m n =
   ( MonadBuildSchemaBase m n,

server/src-lib/Hasura/GraphQL/Schema/Remote.hs

@@ -33,6 +33,7 @@ import Hasura.RQL.IR.Root qualified as IR
 import Hasura.RQL.IR.Value qualified as IR
 import Hasura.RQL.Types.Relationships.Remote
 import Hasura.RQL.Types.ResultCustomization
+import Hasura.RQL.Types.Schema.Options qualified as Options
 import Hasura.RQL.Types.SchemaCache
 import Hasura.RemoteSchema.SchemaCache.Types
 import Language.GraphQL.Draft.Syntax qualified as G
@@ -270,15 +271,18 @@ inputValueDefinitionParser schemaDoc (G.InputValueDefinition desc name fieldType
     doNullability ::
       forall k.
       ('Input <: k) =>
+      Options.RemoteNullForwardingPolicy ->
       G.Nullability ->
       Parser k n (Maybe (Altered, G.Value RemoteSchemaVariable)) ->
       Parser k n (Maybe (Altered, G.Value RemoteSchemaVariable))
-    doNullability (G.Nullability True) parser =
+    doNullability Options.RemoteOnlyForwardNonNull (G.Nullability True) parser =
+      nullable parser `bind` pure . join
+    doNullability Options.RemoteForwardAccurately (G.Nullability True) parser =
       P.nullableExact parser `bind` \case
         P.NullableInputValue x -> pure x
         P.NullableInputNull -> pure $ Just (Altered False, G.VNull)
         P.NullableInputAbsent -> pure Nothing
-    doNullability (G.Nullability False) parser = parser
+    doNullability _nullForwarding (G.Nullability False) parser = parser
 
     fieldConstructor ::
       forall k.
@@ -301,49 +305,51 @@ inputValueDefinitionParser schemaDoc (G.InputValueDefinition desc name fieldType
       ) ->
       G.GType ->
       SchemaT r m (InputFieldsParser n (Maybe (Altered, G.Value RemoteSchemaVariable)))
-    buildField mkInputFieldsParser = \case
-      G.TypeNamed nullability typeName ->
-        case lookupType schemaDoc typeName of
-          Nothing -> throw400 RemoteSchemaError $ "Could not find type with name " <>> typeName
-          Just typeDef -> do
-            customizeTypename <- asks getter
-            case typeDef of
-              G.TypeDefinitionScalar scalarTypeDefn ->
-                pure $ mkInputFieldsParser $ doNullability nullability $ Just <$> remoteFieldScalarParser customizeTypename scalarTypeDefn
-              G.TypeDefinitionEnum defn ->
-                pure $ mkInputFieldsParser $ doNullability nullability $ Just <$> remoteFieldEnumParser customizeTypename defn
-              G.TypeDefinitionObject _ ->
-                throw400 RemoteSchemaError "expected input type, but got output type"
-              G.TypeDefinitionInputObject defn -> do
-                potentialObject <- remoteInputObjectParser schemaDoc defn
-                pure $ case potentialObject of
-                  Left dummyInputFieldsParser -> do
-                    -- We couln't create a parser, meaning we can't create a field for this
-                    -- object. Instead we must return a "pure" InputFieldsParser that always yields
-                    -- the needed result without containing a field definition.
-                    --
-                    -- !!! WARNING #1 !!!
-                    -- Since we have no input field in the schema for this field, we can't make the
-                    -- distinction between it being actually present at parsing time or not. We
-                    -- therefore choose to behave as if it was always present, and we always
-                    -- include the preset values in the result.
-                    --
-                    -- !!! WARNING #2 !!!
-                    -- We are re-using an 'InputFieldsParser' that was created earlier! Won't that
-                    -- create new fields in the current context? No, it won't, but only because in
-                    -- this case we know that it was created from the preset fields in
-                    -- 'argumentsParser', and therefore contains no field definition.
-                    Just <$> dummyInputFieldsParser
-                  Right actualParser -> do
-                    -- We're in the normal case: we do have a parser for the input object, which is
-                    -- therefore valid (non-empty).
-                    mkInputFieldsParser $ doNullability nullability $ Just <$> actualParser
-              G.TypeDefinitionUnion _ ->
-                throw400 RemoteSchemaError "expected input type, but got output type"
-              G.TypeDefinitionInterface _ ->
-                throw400 RemoteSchemaError "expected input type, but got output type"
-      G.TypeList nullability subType -> do
-        buildField (mkInputFieldsParser . doNullability nullability . fmap (Just . fmap G.VList . aggregateListAndAlteration) . P.list) subType
+    buildField mkInputFieldsParser gType = do
+      nullForwarding <- asks getter
+      case gType of
+        G.TypeNamed nullability typeName ->
+          case lookupType schemaDoc typeName of
+            Nothing -> throw400 RemoteSchemaError $ "Could not find type with name " <>> typeName
+            Just typeDef -> do
+              customizeTypename <- asks getter
+              case typeDef of
+                G.TypeDefinitionScalar scalarTypeDefn ->
+                  pure $ mkInputFieldsParser $ doNullability nullForwarding nullability $ Just <$> remoteFieldScalarParser customizeTypename scalarTypeDefn
+                G.TypeDefinitionEnum defn ->
+                  pure $ mkInputFieldsParser $ doNullability nullForwarding nullability $ Just <$> remoteFieldEnumParser customizeTypename defn
+                G.TypeDefinitionObject _ ->
+                  throw400 RemoteSchemaError "expected input type, but got output type"
+                G.TypeDefinitionInputObject defn -> do
+                  potentialObject <- remoteInputObjectParser schemaDoc defn
+                  pure $ case potentialObject of
+                    Left dummyInputFieldsParser -> do
+                      -- We couln't create a parser, meaning we can't create a field for this
+                      -- object. Instead we must return a "pure" InputFieldsParser that always yields
+                      -- the needed result without containing a field definition.
+                      --
+                      -- !!! WARNING #1 !!!
+                      -- Since we have no input field in the schema for this field, we can't make the
+                      -- distinction between it being actually present at parsing time or not. We
+                      -- therefore choose to behave as if it was always present, and we always
+                      -- include the preset values in the result.
+                      --
+                      -- !!! WARNING #2 !!!
+                      -- We are re-using an 'InputFieldsParser' that was created earlier! Won't that
+                      -- create new fields in the current context? No, it won't, but only because in
+                      -- this case we know that it was created from the preset fields in
+                      -- 'argumentsParser', and therefore contains no field definition.
+                      Just <$> dummyInputFieldsParser
+                    Right actualParser -> do
+                      -- We're in the normal case: we do have a parser for the input object, which is
+                      -- therefore valid (non-empty).
+                      mkInputFieldsParser $ doNullability nullForwarding nullability $ Just <$> actualParser
+                G.TypeDefinitionUnion _ ->
+                  throw400 RemoteSchemaError "expected input type, but got output type"
+                G.TypeDefinitionInterface _ ->
+                  throw400 RemoteSchemaError "expected input type, but got output type"
+        G.TypeList nullability subType -> do
+          buildField (mkInputFieldsParser . doNullability nullForwarding nullability . fmap (Just . fmap G.VList . aggregateListAndAlteration) . P.list) subType
 
 -- | remoteFieldScalarParser attempts to parse a scalar value for a given remote field
 --

server/src-lib/Hasura/GraphQL/Schema/RemoteRelationship.hs

@@ -56,7 +56,7 @@ remoteRelationshipField schemaContext schemaOptions sourceCache remoteSchemaCach
           ExcludeRemoteSourceRelationship -> pure Nothing
       RFISchema remoteSchema ->
         -- see Note [SchemaT and stacking]
-        runRemoteSchema schemaContext do
+        runRemoteSchema schemaContext (soRemoteNullForwardingPolicy schemaOptions) do
           fields <- remoteRelationshipToSchemaField remoteSchemaCache remoteSchemaPermissions _rfiLHS remoteSchema
           pure $ fmap (pure . fmap IR.RemoteSchemaField) fields
 

server/src-lib/Hasura/RQL/Types/Common.hs

@@ -299,6 +299,7 @@ isSystemDefined = unSystemDefined
 data SQLGenCtx = SQLGenCtx
   { stringifyNum :: Options.StringifyNumbers,
     dangerousBooleanCollapse :: Options.DangerouslyCollapseBooleans,
+    remoteNullForwardingPolicy :: Options.RemoteNullForwardingPolicy,
     optimizePermissionFilters :: Options.OptimizePermissionFilters,
     bigqueryStringNumericInput :: Options.BigQueryStringNumericInput
   }

server/src-lib/Hasura/RQL/Types/Schema/Options.hs

@@ -4,6 +4,7 @@ module Hasura.RQL.Types.Schema.Options
   ( SchemaOptions (..),
     StringifyNumbers (..),
     DangerouslyCollapseBooleans (..),
+    RemoteNullForwardingPolicy (..),
     InferFunctionPermissions (..),
     RemoteSchemaPermissions (..),
     OptimizePermissionFilters (..),
@@ -24,6 +25,7 @@ import Hasura.Prelude
 data SchemaOptions = SchemaOptions
   { soStringifyNumbers :: StringifyNumbers,
     soDangerousBooleanCollapse :: DangerouslyCollapseBooleans,
+    soRemoteNullForwardingPolicy :: RemoteNullForwardingPolicy,
     soInferFunctionPermissions :: InferFunctionPermissions,
     soOptimizePermissionFilters :: OptimizePermissionFilters,
     soIncludeUpdateManyFields :: IncludeUpdateManyFields,
@@ -87,6 +89,24 @@ instance ToJSON DangerouslyCollapseBooleans where
     DangerouslyCollapseBooleans -> Bool True
     Don'tDangerouslyCollapseBooleans -> Bool False
 
+data RemoteNullForwardingPolicy
+  = RemoteForwardAccurately
+  | RemoteOnlyForwardNonNull
+  deriving (Show, Eq)
+
+instance FromJSON RemoteNullForwardingPolicy where
+  parseJSON =
+    withBool "RemoteNullForwardingPolicy"
+      $ pure
+      . \case
+        False -> RemoteForwardAccurately
+        True -> RemoteOnlyForwardNonNull
+
+instance ToJSON RemoteNullForwardingPolicy where
+  toJSON = \case
+    RemoteForwardAccurately -> Bool False
+    RemoteOnlyForwardNonNull -> Bool True
+
 -- | Should we infer function permissions? If this flag is set to
 -- 'InferFunctionPermissions', we may fail to build expression parsers
 -- in 'buildQueryAndSubscriptionFields' for users with unrecognised roles.

server/src-lib/Hasura/Server/Init.hs

@@ -169,6 +169,7 @@ mkServeOptions sor@ServeOptionsRaw {..} = do
       Options.Don'tStringifyNumbers -> withOptionDefault Nothing stringifyNumOption
       stringifyNums -> pure stringifyNums
   soDangerousBooleanCollapse <- withOptionDefault rsoDangerousBooleanCollapse dangerousBooleanCollapseOption
+  soRemoteNullForwardingPolicy <- withOptionDefault rsoRemoteNullForwardingPolicy remoteNullForwardingPolicyOption
   soEnabledAPIs <- withOptionDefault rsoEnabledAPIs enabledAPIsOption
   soLiveQueryOpts <- do
     _lqoRefetchInterval <- withOptionDefault rsoMxRefetchInt mxRefetchDelayOption

server/src-lib/Hasura/Server/Init/Arg/Command/Serve.hs

@@ -31,6 +31,7 @@ module Hasura.Server.Init.Arg.Command.Serve
     wsReadCookieOption,
     stringifyNumOption,
     dangerousBooleanCollapseOption,
+    remoteNullForwardingPolicyOption,
     enabledAPIsOption,
     mxRefetchDelayOption,
     mxBatchSizeOption,
@@ -119,6 +120,7 @@ serveCommandParser =
     <*> parseWsReadCookie
     <*> parseStringifyNum
     <*> parseDangerousBooleanCollapse
+    <*> parseRemoteNullForwardingPolicy
     <*> parseEnabledAPIs
     <*> parseMxRefetchDelay
     <*> parseMxBatchSize
@@ -628,6 +630,24 @@ dangerousBooleanCollapseOption =
           <> " [DEPRECATED, WILL BE REMOVED SOON] (default: false)"
     }
 
+parseRemoteNullForwardingPolicy :: Opt.Parser (Maybe Options.RemoteNullForwardingPolicy)
+parseRemoteNullForwardingPolicy =
+  fmap (bool Nothing (Just Options.RemoteOnlyForwardNonNull))
+    $ Opt.switch
+      ( Opt.long "remote-schema-skip-nulls"
+          <> Opt.help (Config._helpMessage remoteNullForwardingPolicyOption)
+      )
+
+remoteNullForwardingPolicyOption :: Config.Option Options.RemoteNullForwardingPolicy
+remoteNullForwardingPolicyOption =
+  Config.Option
+    { Config._default = Options.RemoteForwardAccurately,
+      Config._envVar = "HASURA_GRAPHQL_REMOTE_SCHEMA_SKIP_NULLS",
+      Config._helpMessage =
+        "Skip null values from arguments while resolving fields from remote schemas. (default: false, i.e."
+          <> " forward null values in argument as well)"
+    }
+
 parseEnabledAPIs :: Opt.Parser (Maybe (HashSet Config.API))
 parseEnabledAPIs =
   Opt.optional
@@ -1295,6 +1315,7 @@ serveCmdFooter =
         Config.optionPP metadataDBExtensionsSchemaOption,
         Config.optionPP apolloFederationStatusOption,
         Config.optionPP closeWebsocketsOnMetadataChangeOption,
-        Config.optionPP maxTotalHeaderLengthOption
+        Config.optionPP maxTotalHeaderLengthOption,
+        Config.optionPP remoteNullForwardingPolicyOption
       ]
     eventEnvs = [Config.optionPP graphqlEventsHttpPoolSizeOption, Config.optionPP graphqlEventsFetchIntervalOption]

server/src-lib/Hasura/Server/Init/Config.hs

@@ -290,6 +290,7 @@ data ServeOptionsRaw impl = ServeOptionsRaw
     rsoWsReadCookie :: WsReadCookieStatus,
     rsoStringifyNum :: Schema.Options.StringifyNumbers,
     rsoDangerousBooleanCollapse :: Maybe Schema.Options.DangerouslyCollapseBooleans,
+    rsoRemoteNullForwardingPolicy :: Maybe Schema.Options.RemoteNullForwardingPolicy,
     rsoEnabledAPIs :: Maybe (HashSet API),
     rsoMxRefetchInt :: Maybe Subscription.Options.RefetchInterval,
     rsoMxBatchSize :: Maybe Subscription.Options.BatchSize,
@@ -591,6 +592,7 @@ data ServeOptions impl = ServeOptions
     soEnableTelemetry :: TelemetryStatus,
     soStringifyNum :: Schema.Options.StringifyNumbers,
     soDangerousBooleanCollapse :: Schema.Options.DangerouslyCollapseBooleans,
+    soRemoteNullForwardingPolicy :: Schema.Options.RemoteNullForwardingPolicy,
     soEnabledAPIs :: HashSet API,
     soLiveQueryOpts :: Subscription.Options.LiveQueriesOptions,
     soStreamingQueryOpts :: Subscription.Options.StreamQueriesOptions,

server/src-lib/Hasura/Server/Init/Env.hs

@@ -253,6 +253,9 @@ instance FromEnv Options.RemoteSchemaPermissions where
 instance FromEnv Options.DangerouslyCollapseBooleans where
   fromEnv = fmap (bool Options.Don'tDangerouslyCollapseBooleans Options.DangerouslyCollapseBooleans) . fromEnv @Bool
 
+instance FromEnv Options.RemoteNullForwardingPolicy where
+  fromEnv = fmap (bool Options.RemoteForwardAccurately Options.RemoteOnlyForwardNonNull) . fromEnv @Bool
+
 instance FromEnv Options.InferFunctionPermissions where
   fromEnv = fmap (bool Options.Don'tInferFunctionPermissions Options.InferFunctionPermissions) . fromEnv @Bool
 

server/src-test/Hasura/GraphQL/Schema/RemoteSpec.hs

@@ -32,6 +32,7 @@ import Hasura.RQL.IR.Root
 import Hasura.RQL.IR.Value
 import Hasura.RQL.Types.Common
 import Hasura.RQL.Types.Roles (adminRoleName)
+import Hasura.RQL.Types.Schema.Options qualified as Options
 import Hasura.RemoteSchema.SchemaCache
 import Hasura.Session (BackendOnlyFieldAccess (..), SessionVariables, UserInfo (..), mkSessionVariable)
 import Language.GraphQL.Draft.Parser qualified as G
@@ -137,7 +138,7 @@ buildQueryParsers introspection = do
   RemoteSchemaParser query _ _ <-
     runError
       $ runMemoizeT
-      $ runRemoteSchema schemaContext
+      $ runRemoteSchema schemaContext Options.RemoteForwardAccurately
       $ buildRemoteParser introResult remoteSchemaRels remoteSchemaInfo
   pure
     $ head query

server/src-test/Hasura/Server/InitSpec.hs

@@ -64,6 +64,7 @@ emptyServeOptionsRaw =
       rsoWsReadCookie = UUT.WsReadCookieDisabled,
       rsoStringifyNum = Options.Don'tStringifyNumbers,
       rsoDangerousBooleanCollapse = Nothing,
+      rsoRemoteNullForwardingPolicy = Nothing,
       rsoEnabledAPIs = Nothing,
       rsoMxRefetchInt = Nothing,
       rsoMxBatchSize = Nothing,

server/src-test/Test/Parser/Monad.hs

@@ -64,6 +64,7 @@ defaultSchemaOptions =
   SchemaOptions
     { soStringifyNumbers = Options.Don'tStringifyNumbers,
       soDangerousBooleanCollapse = Options.Don'tDangerouslyCollapseBooleans,
+      soRemoteNullForwardingPolicy = Options.RemoteForwardAccurately,
       soInferFunctionPermissions = Options.InferFunctionPermissions,
       soOptimizePermissionFilters = Options.Don'tOptimizePermissionFilters,
       soIncludeUpdateManyFields = Options.IncludeUpdateManyFields,

server/test-postgres/Constants.hs

@@ -62,6 +62,7 @@ serveOptions =
       soEnableTelemetry = Init.TelemetryDisabled,
       soStringifyNum = Options.Don'tStringifyNumbers,
       soDangerousBooleanCollapse = Options.Don'tDangerouslyCollapseBooleans,
+      soRemoteNullForwardingPolicy = Options.RemoteForwardAccurately,
       soEnabledAPIs = testSuiteEnabledApis,
       soLiveQueryOpts = ES.mkSubscriptionsOptions Nothing Nothing,
       soStreamingQueryOpts = ES.mkSubscriptionsOptions Nothing Nothing,

server/test-postgres/Main.hs

@@ -105,6 +105,7 @@ main = do
               SQLGenCtx
                 Options.Don'tStringifyNumbers
                 Options.Don'tDangerouslyCollapseBooleans
+                Options.RemoteForwardAccurately
                 Options.Don'tOptimizePermissionFilters
                 Options.EnableBigQueryStringNumericInput
             maintenanceMode = MaintenanceModeDisabled