From 46291c7ad509049caeb32bcf37220b95c26f1a5b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20W=C3=B6lk?= <max@mwoelk.de>
Date: Fri, 9 Apr 2021 09:27:56 +0200
Subject: [PATCH] fix(graphql,federation,#1051): check for undefined as well

---
 examples/federation/graphql-gateway/src/app.module.ts        | 1 +
 .../src/resolvers/relations/references-relation.resolver.ts  | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/examples/federation/graphql-gateway/src/app.module.ts b/examples/federation/graphql-gateway/src/app.module.ts
index bcdcaf514..7e1c55d2b 100644
--- a/examples/federation/graphql-gateway/src/app.module.ts
+++ b/examples/federation/graphql-gateway/src/app.module.ts
@@ -13,6 +13,7 @@ import { GraphQLGatewayModule } from '@nestjs/graphql';
           { name: 'todo-items', url: 'http://localhost:3001/graphql' },
           { name: 'sub-tasks', url: 'http://localhost:3002/graphql' },
           { name: 'tags', url: 'http://localhost:3003/graphql' },
+          { name: 'user', url: 'http://localhost:3004/graphql' },
         ],
       },
     }),
diff --git a/packages/query-graphql/src/resolvers/relations/references-relation.resolver.ts b/packages/query-graphql/src/resolvers/relations/references-relation.resolver.ts
index 0fa2add90..e69cc8fed 100644
--- a/packages/query-graphql/src/resolvers/relations/references-relation.resolver.ts
+++ b/packages/query-graphql/src/resolvers/relations/references-relation.resolver.ts
@@ -17,7 +17,10 @@ const pluckFields = <DTO, Relation>(dto: DTO, fieldMap: ReferencesKeys<DTO, Rela
 };
 
 const allFieldsAreNull = <Relation>(fields: Partial<Relation>): boolean => {
-  return Object.entries(fields).reduce<boolean>((previousNull, [, value]) => previousNull && value === null, true);
+  return Object.entries(fields).reduce<boolean>(
+    (previousNull, [, value]) => previousNull && (value === null || value === undefined),
+    true,
+  );
 };
 
 const ReferencesMixin = <DTO, Relation>(DTOClass: Class<DTO>, reference: ResolverRelationReference<DTO, Relation>) => <