fix(federation): merge the elements if the shared root field is a list (

#6238)

* fix(federation): merge the elements if the shared root field is a list

* Go

.changeset/tame-rabbits-cheat.md

@@ -0,0 +1,11 @@
+---
+'@graphql-tools/federation': patch
+---
+
+Merge the elements of the lists if the root field is shared across different subgraphs
+
+```graphql
+type Query {
+  products: [Product] # If this field is returned by multiple subgraphs, the elements of the lists will be merged
+}
+```

.changeset/thick-grapes-shop.md

@@ -0,0 +1,11 @@
+---
+'@graphql-tools/utils': patch
+---
+
+If the given objects are arrays with the same length, merge the elements.
+
+```ts
+const a = [{ a: 1 }, { b: 2 }];
+const b = [{ c: 3 }, { d: 4 }];
+const result = mergeDeep(a, b); // [{ a: 1, c: 3 }, { b: 2, d: 4 }]
+```

package.json

@@ -17,6 +17,7 @@
     "website",
     "benchmark/*"
   ],
+  "packageManager": "[email protected]+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e",
   "keywords": [
     "GraphQL",
     "Apollo",

packages/executor/src/execution/__tests__/error-handling.test.ts

@@ -83,7 +83,7 @@ describe('Error Handling', () => {
       if (process.versions['node'].startsWith('18.')) {
         expect(errorMessage).toBe('Unexpected end of JSON input');
       } else {
-        expect(errorMessage).toBe(
+        expect(errorMessage).toContain(
           "Expected ',' or '}' after property value in JSON at position 17",
         );
       }

packages/federation/src/supergraph.ts

@@ -1043,7 +1043,7 @@ export function getStitchingOptionsFromSupergraphSdl(
             return jobs[0];
           }
           if (hasPromise) {
-            return Promise.all(jobs).then(results => mergeDeep(results));
+            return Promise.all(jobs).then(results => mergeDeep(results, false, true, true));
           }
           return mergeDeep(jobs);
         },

packages/federation/test/fixtures/federation-compatibility/entity-and-no-entity/tests.json

@@ -21,6 +21,6 @@
         ]
       }
     },
-    "plan": "\n    QueryPlan {\n      Parallel {\n        Sequence {\n          Fetch(service: \"a\") {\n            {\n              users {\n                __typename\n                id\n              }\n            }\n          },\n          Flatten(path: \"users.@\") {\n            Fetch(service: \"b\") {\n              {\n                ... on User {\n                  __typename\n                  id\n                }\n              } =>\n              {\n                ... on User {\n                  name\n                }\n              }\n            },\n          },\n        },\n        Fetch(service: \"b\") {\n          {\n            accounts {\n              __typename\n              ... on User {\n                id\n                name\n              }\n              ... on Admin {\n                id__alias_0: id\n                photo\n              }\n            }\n          }\n        },\n      },\n    }\n    "
+    "plan": "\n    QueryPlan {\n      Parallel {\n        Sequence {\n          Fetch(service: \"a\") {\n            {\n              users {\n                __typename\n                id\n              }\n            }\n          },\n          Flatten(path: \"users.@\") {\n            Fetch(service: \"b\") {\n              {\n                ... on User {\n                  __typename\n                  id\n                }\n              } =>\n              {\n                ... on User {\n                  name\n                }\n              }\n            },\n          },\n        },\n        Fetch(service: \"b\") {\n          {\n            accounts {\n              __typename\n              ... on User {\n                id\n                name\n              }\n              ... on Admin {\n                # NOTE:\n                # User.id and Admin.id have similar output types,\n                # but one returns a non-nullable field and the other a nullable field.\n                # To avoid a GraphQL error, we need to alias the field.\n                id__alias_0: id\n                photo\n              }\n            }\n          }\n        },\n      },\n    }\n    "
   }
 ]

packages/federation/test/fixtures/federation-compatibility/mutations/tests.json

@@ -29,7 +29,7 @@
     "plan": "\n      QueryPlan {\n        Sequence {\n          Fetch(service: \"a\") {\n            {\n              product(id: \"p1\") {\n                __typename\n                id\n                name\n                price\n              }\n            }\n          },\n          Flatten(path: \"product\") {\n            Fetch(service: \"b\") {\n              {\n                ... on Product {\n                  __typename\n                  id\n                  price\n                }\n              } =>\n              {\n                ... on Product {\n                  isExpensive\n                  isAvailable\n                }\n              }\n            },\n          },\n        },\n      }\n      "
   },
   {
-    "query": "\n      mutation {\n        five: add(num: 5, requestId: \"7c8c0a7323709\")\n        ten: multiply(by: 2, requestId: \"7c8c0a7323709\")\n        twelve: add(num: 2, requestId: \"7c8c0a7323709\")\n        final: delete(requestId: \"7c8c0a7323709\")\n      }\n    ",
+    "query": "\n      mutation {\n        five: add(num: 5, requestId: \"818c6d2a6f5ec\")\n        ten: multiply(by: 2, requestId: \"818c6d2a6f5ec\")\n        twelve: add(num: 2, requestId: \"818c6d2a6f5ec\")\n        final: delete(requestId: \"818c6d2a6f5ec\")\n      }\n    ",
     "expected": {
       "data": {
         "five": 5,
@@ -38,6 +38,6 @@
         "final": 12
       }
     },
-    "plan": "\n      QueryPlan {\n        Sequence {\n          Fetch(service: \"c\") {\n            {\n              five: add(num: 5, requestId: \"7c8c0a7323709\")\n            }\n          },\n          Fetch(service: \"a\") {\n            {\n              ten: multiply(by: 2, requestId: \"7c8c0a7323709\")\n            }\n          },\n          Fetch(service: \"c\") {\n            {\n              twelve: add(num: 2, requestId: \"7c8c0a7323709\")\n            }\n          },\n          Fetch(service: \"b\") {\n            {\n              final: delete(requestId: \"7c8c0a7323709\")\n            }\n          },\n        },\n      }\n      "
+    "plan": "\n      QueryPlan {\n        Sequence {\n          Fetch(service: \"c\") {\n            {\n              five: add(num: 5, requestId: \"818c6d2a6f5ec\")\n            }\n          },\n          Fetch(service: \"a\") {\n            {\n              ten: multiply(by: 2, requestId: \"818c6d2a6f5ec\")\n            }\n          },\n          Fetch(service: \"c\") {\n            {\n              twelve: add(num: 2, requestId: \"818c6d2a6f5ec\")\n            }\n          },\n          Fetch(service: \"b\") {\n            {\n              final: delete(requestId: \"818c6d2a6f5ec\")\n            }\n          },\n        },\n      }\n      "
   }
 ]

packages/federation/test/fixtures/federation-compatibility/shared-root/supergraph.graphql

@@ -58,4 +58,5 @@ type Query
   @join__type(graph: PRICE)
 {
   product: Product
+  products: [Product]
 }

packages/federation/test/fixtures/federation-compatibility/shared-root/tests.json

@@ -12,5 +12,21 @@
       }
     },
     "plan": "\n    QueryPlan {\n      # NOTE\n      # What's interesting here is that the most efficient way to fetch the data\n      # is to make parallel calls to Query.products in each service.\n      # Each service has a different field that it can provide.\n      Parallel {\n        Fetch(service: \"name\") {\n          {\n            product {\n              name\n            }\n          }\n        },\n        Fetch(service: \"category\") {\n          {\n            product {\n              category\n              id\n            }\n          }\n        },\n        Fetch(service: \"price\") {\n          {\n            product {\n              price\n            }\n          }\n        },\n      },\n    }\n    "
+  },
+  {
+    "query": "\n      query {\n        products {\n          id\n          name\n          category\n          price\n        }\n      }\n    ",
+    "expected": {
+      "data": {
+        "products": [
+          {
+            "id": "1",
+            "name": "Product 1",
+            "price": 100,
+            "category": "Category 1"
+          }
+        ]
+      }
+    },
+    "plan": "\n    QueryPlan {\n      # NOTE\n      # What's interesting here is that the most efficient way to fetch the data\n      # is to make parallel calls to Query.products in each service.\n      # Each service has a different field that it can provide.\n      Parallel {\n        Fetch(service: \"name\") {\n          {\n            products {\n              name\n            }\n          }\n        },\n        Fetch(service: \"category\") {\n          {\n            products {\n              category\n              id\n            }\n          }\n        },\n        Fetch(service: \"price\") {\n          {\n            products {\n              price\n            }\n          }\n        },\n      },\n    }\n    "
   }
 ]

packages/utils/src/mergeDeep.ts

@@ -12,13 +12,38 @@ export function mergeDeep<S extends any[]>(
   respectArrays = false,
   respectArrayLength = false,
 ): UnboxIntersection<UnionToIntersection<BoxedTupleTypes<S>>> & any {
-  const target = sources[0] || {};
+  if (respectArrays && respectArrayLength) {
+    let expectedLength: number | undefined;
+    const areArraysInTheSameLength = sources.every(source => {
+      if (Array.isArray(source)) {
+        if (expectedLength === undefined) {
+          expectedLength = source.length;
+          return true;
+        } else if (expectedLength === source.length) {
+          return true;
+        }
+      }
+      return false;
+    });
+
+    if (areArraysInTheSameLength) {
+      return new Array(expectedLength).fill(null).map((_, index) =>
+        mergeDeep(
+          sources.map(source => source[index]),
+          respectPrototype,
+          respectArrays,
+          respectArrayLength,
+        ),
+      );
+    }
+  }
+
   const output = {};
   if (respectPrototype) {
-    Object.setPrototypeOf(output, Object.create(Object.getPrototypeOf(target)));
+    Object.setPrototypeOf(output, Object.create(Object.getPrototypeOf(sources[0])));
   }
   for (const source of sources) {
-    if (isObject(target) && isObject(source)) {
+    if (isObject(source)) {
       if (respectPrototype) {
         const outputPrototype = Object.getPrototypeOf(output);
         const sourcePrototype = Object.getPrototypeOf(source);
@@ -41,31 +66,28 @@ export function mergeDeep<S extends any[]>(
               [output[key], source[key]] as S,
               respectPrototype,
               respectArrays,
+              respectArrayLength,
             );
           }
         } else if (respectArrays && Array.isArray(output[key])) {
           if (Array.isArray(source[key])) {
-            output[key].push(...source[key]);
+            if (respectArrayLength && output[key].length === source[key].length) {
+              output[key] = mergeDeep(
+                [output[key], source[key]] as S,
+                respectPrototype,
+                respectArrays,
+                respectArrayLength,
+              );
+            } else {
+              output[key].push(...source[key]);
+            }
           } else {
             output[key].push(source[key]);
           }
         } else {
           Object.assign(output, { [key]: source[key] });
         }
       }
-    } else if (respectArrays && Array.isArray(target)) {
-      if (Array.isArray(source)) {
-        if (respectArrayLength && source.length === target.length) {
-          return target.map((targetElem, i) =>
-            mergeDeep([targetElem, source[i]], respectPrototype, respectArrays, respectArrayLength),
-          );
-        }
-        target.push(...source);
-      } else {
-        target.push(source);
-      }
-    } else if (respectArrays && Array.isArray(source)) {
-      return [target, ...source];
     }
   }
   return output;

packages/utils/tests/mergeDeep.test.ts

@@ -54,8 +54,16 @@ describe('mergeDeep', () => {
   });
 
   it('merges arrays', () => {
-    const x = { a: [1, 2] };
+    const x = { a: [1, 2, 5] };
     const y = { a: [3, 4] };
-    expect(mergeDeep([x, y], false, true)).toEqual({ a: [1, 2, 3, 4] });
+    expect(mergeDeep([x, y], false, true)).toEqual({ a: [1, 2, 5, 3, 4] });
+  });
+  it('merges arrays with the same length', () => {
+    const x = [{ a: 1 }, { b: 2 }];
+    const y = [{ c: 3 }, { d: 4 }];
+    expect(mergeDeep([x, y], false, true, true)).toEqual([
+      { a: 1, c: 3 },
+      { b: 2, d: 4 },
+    ]);
   });
 });