Server: Don't throw validation error while creating remote relationship joining singular type with array type

CHANGELOG.md

@@ -21,6 +21,7 @@ If you do have such headers configured, then you must update the header configur
 - server: add logs for action handlers
 - server: add request/response sizes in event triggers (and scheduled trigger) logs (#5463)
 - server: change startup log kind `db_migrate` to `catalog_migrate` (#5531)
+- server: don't throw validation error when creating remote relationships joining singleton type with array type with same base type (fixes #5133)
 - console: handle nested fragments in allowed queries (close #5137) (#5252)
 - console: update sidebar icons for different action and trigger types (#5445)
 - console: make add column UX consistent with others (#5486)

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

@@ -10,6 +10,7 @@ module Hasura.GraphQL.Utils
   , unwrapTy
   , simpleGraphQLQuery
   , jsonValueToGValue
+  , getBaseTyWithNestedLevelsCount
   ) where
 
 import           Hasura.Prelude
@@ -40,6 +41,15 @@ getBaseTy = \case
   where
     getBaseTyL = getBaseTy . G.unListType
 
+getBaseTyWithNestedLevelsCount :: G.GType -> (G.NamedType, Int)
+getBaseTyWithNestedLevelsCount ty = go ty 0
+  where
+    go :: G.GType -> Int -> (G.NamedType, Int)
+    go gType ctr =
+      case gType of
+        G.TypeNamed _ n  -> (n, ctr)
+        G.TypeList  _ lt -> flip go (ctr + 1) (G.unListType lt)
+
 unwrapTy :: G.GType -> G.GType
 unwrapTy =
   \case

server/src-lib/Hasura/RQL/DDL/RemoteRelationship/Validate.hs

@@ -65,7 +65,7 @@ validateErrorToText (toList -> errs) =
       TableFieldNonexistent table fieldName ->
         "field with name " <> fieldName <<> " not found in table " <>> table
       ExpectedTypeButGot expTy actualTy ->
-        "expected type " <> getBaseTy expTy <<> " but got " <>> getBaseTy actualTy
+        "expected type " <> G.showGT expTy <<> " but got " <>> G.showGT actualTy
       InvalidType ty err ->
         "type " <> getBaseTy ty <<> err
       InvalidVariable var _ ->
@@ -363,12 +363,12 @@ validateType permittedVariables value expectedGType types =
         Just fieldInfo ->
           bindValidation
             (columnInfoToNamedType fieldInfo)
-            (\actualNamedType -> assertType (G.toGT actualNamedType) expectedGType)
-    G.VInt {} -> assertType (G.toGT $ mkScalarTy PGInteger) expectedGType
-    G.VFloat {} -> assertType (G.toGT $ mkScalarTy PGFloat) expectedGType
-    G.VBoolean {} -> assertType (G.toGT $ mkScalarTy PGBoolean) expectedGType
+            (\actualNamedType -> isTypeCoercible (G.toGT actualNamedType) expectedGType)
+    G.VInt {} -> isTypeCoercible (G.toGT $ mkScalarTy PGInteger) expectedGType
+    G.VFloat {} -> isTypeCoercible (G.toGT $ mkScalarTy PGFloat) expectedGType
+    G.VBoolean {} -> isTypeCoercible (G.toGT $ mkScalarTy PGBoolean) expectedGType
     G.VNull -> Failure (pure NullNotAllowedHere)
-    G.VString {} -> assertType (G.toGT $ mkScalarTy PGText) expectedGType
+    G.VString {} -> isTypeCoercible (G.toGT $ mkScalarTy PGText) expectedGType
     G.VEnum _ -> Failure (pure UnsupportedEnum)
     G.VList (G.unListValue -> values) -> do
       case values of
@@ -405,19 +405,25 @@ validateType permittedVariables value expectedGType types =
                         (G.toGT $ G.NamedType name)
                         "not an input object type"))
 
-assertType :: G.GType -> G.GType -> Validation (NonEmpty ValidationError) ()
-assertType actualType expectedType = do
-  -- check if both are list types or both are named types
-  (when
-     (isListType' actualType /= isListType' expectedType)
-     (Failure (pure $ ExpectedTypeButGot expectedType actualType)))
-  -- if list type then check over unwrapped type, else check base types
-  if isListType' actualType
-    then assertType (unwrapTy actualType) (unwrapTy expectedType)
-    else (when
-            (getBaseTy actualType /= getBaseTy expectedType)
-            (Failure (pure $ ExpectedTypeButGot expectedType actualType)))
-  pure ()
+isTypeCoercible :: G.GType -> G.GType -> Validation (NonEmpty ValidationError) ()
+isTypeCoercible actualType expectedType =
+  -- The GraphQL spec says that, a singleton type can be coerced into  an array
+  -- type. Which means that if the 'actualType' is a singleton type, like
+  -- 'Int' we should be able to join this with a remote node, which expects an
+  -- input argument of type '[Int]'
+  -- http://spec.graphql.org/June2018/#sec-Type-System.List
+  let (actualBaseType, actualNestingLevel) = getBaseTyWithNestedLevelsCount actualType
+      (expectedBaseType, expectedNestingLevel) = getBaseTyWithNestedLevelsCount expectedType
+  in
+  if actualBaseType == expectedBaseType
+  then if (actualNestingLevel == expectedNestingLevel || actualNestingLevel == 0)
+  -- The check of 'actualNestedCount == 0' is the case of coercing a singleton type
+  -- into an array type
+       then pure ()
+       else Failure (pure $ ExpectedTypeButGot expectedType actualType)
+       --  we cannot coerce two types with different nesting levels,
+       -- for example, we cannot coerce [Int] to [[Int]]
+  else Failure (pure $ ExpectedTypeButGot expectedType actualType)
 
 assertListType :: G.GType -> Validation (NonEmpty ValidationError) ()
 assertListType actualType =

server/tests-py/queries/remote_schemas/remote_relationships/basic_relationship_joining_singleton_with_array.yaml

@@ -0,0 +1,26 @@
+description: Simple Remote relationship with singleton input value type joining to an expected array input type
+url: /v1/graphql
+status: 200
+response:
+  data:
+    profiles:
+      - id: 1
+        remoteUsers:
+        - user_id: 1
+          userMessages:
+          - id: 1
+            msg: "You win!"
+query:
+  query: |
+    query {
+      profiles(where:{ id: { _eq: 1}}) {
+        id
+        remoteUsers {
+          user_id
+          userMessages {
+            id
+            msg
+          }
+        }
+      }
+    }

server/tests-py/queries/remote_schemas/remote_relationships/setup_remote_rel_joining_singleton_with_array.yaml

@@ -0,0 +1,25 @@
+type: bulk
+args:
+- type: create_remote_relationship
+  args:
+    name: remoteUsers
+    table: profiles
+    hasura_fields:
+      - id
+    remote_schema: my-remote-schema
+    remote_field:
+      users:
+        arguments:
+          user_ids: "$id"
+
+- type: create_remote_relationship
+  args:
+    name: remoteUsersMultipleIds
+    table: profiles
+    hasura_fields:
+      - id
+    remote_schema: my-remote-schema
+    remote_field:
+      users:
+        arguments:
+          user_ids: ["$id"]

server/tests-py/remote_schemas/nodejs/index.js

@@ -53,6 +53,7 @@ const typeDefs = gql`
     hello: String
     messages(where: MessageWhereInpObj, includes: IncludeInpObj): [Message]
     user(user_id: Int!): User
+    users(user_ids: [Int]!): [User]
     message(id: Int!) : Message
     communications(id: Int): [Communication]
   }
@@ -175,6 +176,13 @@ const resolvers = {
         user: (_, { user_id }) => {
             return { "user_id": user_id };
         },
+        users: (parent, args, context, info) => {
+            var results = []
+            for (userId of args.user_ids) {
+                results.push({"user_id":userId})
+            }
+            return results;
+        },
         communications: (_, { id }) => {
             var result = allMessages;
             if(id) {

server/tests-py/test_remote_relationships.py

@@ -54,6 +54,9 @@ def test_create_valid(self, hge_ctx):
         st_code, resp = hge_ctx.v1q_f(self.dir() + 'setup_remote_rel_multiple_fields.yaml')
         assert st_code == 200, resp
 
+        st_code, resp = hge_ctx.v1q_f(self.dir() + 'setup_remote_rel_joining_singleton_with_array.yaml')
+        assert st_code == 200, resp
+
         # st_code, resp = hge_ctx.v1q_f(self.dir() + 'setup_remote_rel_with_interface.yaml')
         # assert st_code == 200, resp
 
@@ -157,6 +160,11 @@ def test_basic_relationship_on_object(self, hge_ctx):
         assert st_code == 200, resp
         check_query_f(hge_ctx, self.dir() + 'query_with_arr_rel.yaml')
 
+    def test_basic_relationship_joining_singleton_to_array(self, hge_ctx):
+        st_code, resp = hge_ctx.v1q_f(self.dir() + 'setup_remote_rel_joining_singleton_with_array.yaml')
+        assert st_code == 200, resp
+        check_query_f(hge_ctx, self.dir() + 'basic_relationship_joining_singleton_with_array.yaml')
+
     def test_basic_array(self, hge_ctx):
         st_code, resp = hge_ctx.v1q_f(self.dir() + 'setup_remote_rel_array.yaml')
         assert st_code == 200, resp