Always send variables required for query

packages/apollo-gateway/src/__tests__/__fixtures__/schemas/accounts.ts

@@ -22,7 +22,7 @@ export const typeDefs = gql`
     id: ID!
     name: String
     username: String
-    birthDate: String
+    birthDate(locale: String): String
     account: AccountType
   }
 
@@ -62,6 +62,11 @@ export const resolvers: GraphQLResolverMap<any> = {
     __resolveObject(object) {
       return users.find(user => user.id === object.id);
     },
+    birthDate(user, args) {
+      return args.locale
+        ? new Date(user.birthDate).toLocaleDateString(args.locale)
+        : user.birthDate;
+    },
   },
   Mutation: {
     login(_, args) {

packages/apollo-gateway/src/__tests__/executeQueryPlan.test.ts

@@ -325,6 +325,75 @@ describe('executeQueryPlan', () => {
     `);
   });
 
+  it('should include variables in non-root requests', async () => {
+    const query = gql`
+      query Test($locale: String) {
+        topReviews {
+          body
+          author {
+            name
+            birthDate(locale: $locale)
+          }
+        }
+      }
+    `;
+
+    const operationContext = buildOperationContext(schema, query);
+    const queryPlan = buildQueryPlan(operationContext);
+
+    const requestContext = buildRequestContext();
+    requestContext.request.variables = { locale: 'en-US' };
+
+    const response = await executeQueryPlan(
+      queryPlan,
+      serviceMap,
+      requestContext,
+      operationContext,
+    );
+
+    expect(response.data).toMatchInlineSnapshot(`
+      Object {
+        "topReviews": Array [
+          Object {
+            "author": Object {
+              "birthDate": "12/10/1815",
+              "name": "Ada Lovelace",
+            },
+            "body": "Love it!",
+          },
+          Object {
+            "author": Object {
+              "birthDate": "12/10/1815",
+              "name": "Ada Lovelace",
+            },
+            "body": "Too expensive.",
+          },
+          Object {
+            "author": Object {
+              "birthDate": "6/23/1912",
+              "name": "Alan Turing",
+            },
+            "body": "Could be better.",
+          },
+          Object {
+            "author": Object {
+              "birthDate": "6/23/1912",
+              "name": "Alan Turing",
+            },
+            "body": "Prefer something else.",
+          },
+          Object {
+            "author": Object {
+              "birthDate": "6/23/1912",
+              "name": "Alan Turing",
+            },
+            "body": "Wish I had read this before.",
+          },
+        ],
+      }
+    `);
+  });
+
   it('can execute an introspection query', async () => {
     const operationContext = buildOperationContext(
       schema,

packages/apollo-gateway/src/executeQueryPlan.ts

@@ -150,20 +150,20 @@ async function executeFetch<TContext>(
   const entities = Array.isArray(results) ? results : [results];
   if (entities.length < 1) return;
 
-  if (!fetch.requires) {
-    let variables = Object.create(null);
-    if (fetch.variableUsages) {
-      for (const { node, defaultValue } of fetch.variableUsages) {
-        const name = node.name.value;
-        const providedVariables = context.requestContext.request.variables;
-        if (providedVariables && providedVariables[name] !== 'undefined') {
-          variables[name] = providedVariables[name];
-        } else if (defaultValue) {
-          variables[name] = defaultValue;
-        }
+  let variables = Object.create(null);
+  if (fetch.variableUsages) {
+    for (const { node, defaultValue } of fetch.variableUsages) {
+      const name = node.name.value;
+      const providedVariables = context.requestContext.request.variables;
+      if (providedVariables && providedVariables[name] !== 'undefined') {
+        variables[name] = providedVariables[name];
+      } else if (defaultValue) {
+        variables[name] = defaultValue;
       }
     }
+  }
 
+  if (!fetch.requires) {
     const dataReceivedFromService = await sendOperation(
       context,
       operationForRootFetch(fetch, operationType),
@@ -187,10 +187,14 @@ async function executeFetch<TContext>(
       }
     });
 
+    if ('representations' in variables) {
+      throw new Error(`Variables cannot contain key "representations"`);
+    }
+
     const dataReceivedFromService = await sendOperation(
       context,
       operationForEntitiesFetch(fetch),
-      { representations },
+      { ...variables, representations },
     );
 
     if (!dataReceivedFromService) {