fix(batch-delegate): correct error paths in case of batch delegation (#1556)

Co-authored-by: Copilot <[email protected]>

Author: ardatan

.changeset/breezy-weeks-camp.md

@@ -0,0 +1,6 @@
+---
+'@graphql-tools/batch-delegate': patch
+'@graphql-tools/delegate': patch
+---
+
+Correct error paths in case of batch delegation with the same error

packages/batch-delegate/src/batchDelegateToSchema.ts

@@ -1,3 +1,5 @@
+import { pathToArray, relocatedError } from '@graphql-tools/utils';
+import { GraphQLError } from 'graphql';
 import { getLoader } from './getLoader.js';
 import { BatchDelegateOptions } from './types.js';
 
@@ -11,5 +13,11 @@ export function batchDelegateToSchema<TContext = any, K = any, V = any, C = K>(
     return [];
   }
   const loader = getLoader(options);
-  return Array.isArray(key) ? loader.loadMany(key) : loader.load(key);
+  const res = Array.isArray(key) ? loader.loadMany(key) : loader.load(key);
+  return res.catch((error) => {
+    if (options.info?.path && error instanceof GraphQLError) {
+      return relocatedError(error, pathToArray(options.info.path));
+    }
+    return error;
+  });
 }

packages/batch-delegate/tests/errorPaths.test.ts

@@ -0,0 +1,162 @@
+import { batchDelegateToSchema } from '@graphql-tools/batch-delegate';
+import { delegateToSchema } from '@graphql-tools/delegate';
+import { normalizedExecutor } from '@graphql-tools/executor';
+import { makeExecutableSchema } from '@graphql-tools/schema';
+import { stitchSchemas } from '@graphql-tools/stitch';
+import { GraphQLError, parse } from 'graphql';
+import { beforeEach, describe, expect, test, vi } from 'vitest';
+
+class NotFoundError extends GraphQLError {
+  constructor(id: unknown) {
+    super('Not Found', {
+      extensions: { id },
+    });
+  }
+}
+
+describe('preserves error path indices', () => {
+  const getProperty = vi.fn((id: unknown) => {
+    return new NotFoundError(id);
+  });
+
+  beforeEach(() => {
+    getProperty.mockClear();
+  });
+
+  const subschema = makeExecutableSchema({
+    typeDefs: /* GraphQL */ `
+      type Property {
+        id: ID!
+      }
+
+      type Object {
+        id: ID!
+        propertyId: ID!
+      }
+
+      type Query {
+        objects: [Object!]!
+        propertyById(id: ID!): Property
+        propertiesByIds(ids: [ID!]!): [Property]!
+      }
+    `,
+    resolvers: {
+      Query: {
+        objects: () => {
+          return [
+            { id: '1', propertyId: '1' },
+            { id: '2', propertyId: '1' },
+          ];
+        },
+        propertyById: (_, args) => getProperty(args.id),
+        propertiesByIds: (_, args) => args.ids.map(getProperty),
+      },
+    },
+  });
+
+  const subschemas = [subschema];
+  const typeDefs = /* GraphQL */ `
+    extend type Object {
+      property: Property
+    }
+  `;
+
+  const query = /* GraphQL */ `
+    query {
+      objects {
+        id
+        property {
+          id
+        }
+      }
+    }
+  `;
+
+  const expected = {
+    errors: [
+      {
+        message: 'Not Found',
+        extensions: { id: '1' },
+        path: ['objects', 0, 'property'],
+      },
+      {
+        message: 'Not Found',
+        extensions: { id: '1' },
+        path: ['objects', 1, 'property'],
+      },
+    ],
+    data: {
+      objects: [
+        {
+          id: '1',
+          property: null as null,
+        },
+        {
+          id: '2',
+          property: null as null,
+        },
+      ],
+    },
+  };
+
+  test('using delegateToSchema', async () => {
+    const schema = stitchSchemas({
+      subschemas,
+      typeDefs,
+      resolvers: {
+        Object: {
+          property: {
+            selectionSet: '{ propertyId }',
+            resolve: (source, _, context, info) => {
+              return delegateToSchema({
+                schema: subschema,
+                fieldName: 'propertyById',
+                args: { id: source.propertyId },
+                context,
+                info,
+              });
+            },
+          },
+        },
+      },
+    });
+
+    const result = await normalizedExecutor({
+      schema,
+      document: parse(query),
+    });
+
+    expect(getProperty).toHaveBeenCalledTimes(2);
+    expect(result).toMatchObject(expected);
+  });
+
+  test('using batchDelegateToSchema', async () => {
+    const schema = stitchSchemas({
+      subschemas,
+      typeDefs,
+      resolvers: {
+        Object: {
+          property: {
+            selectionSet: '{ propertyId }',
+            resolve: (source, _, context, info) =>
+              batchDelegateToSchema({
+                schema: subschema,
+                fieldName: 'propertiesByIds',
+                key: source.propertyId,
+                context,
+                info,
+              }),
+          },
+        },
+      },
+    });
+
+    const result = await normalizedExecutor({
+      schema,
+      document: parse(query),
+    });
+
+    expect(getProperty).toHaveBeenCalledTimes(1);
+    expect(result).toMatchObject(expected);
+  });
+});

packages/delegate/src/resolveExternalValue.ts

@@ -182,15 +182,15 @@ function resolveExternalList<TContext extends Record<string, any>>(
   );
 }
 
-const reportedErrors = new WeakMap<GraphQLError, boolean>();
+const reportedErrors = new WeakSet<GraphQLError>();
 
 function reportUnpathedErrorsViaNull(unpathedErrors: Array<GraphQLError>) {
   if (unpathedErrors.length) {
     const unreportedErrors: Array<GraphQLError> = [];
     for (const error of unpathedErrors) {
       if (!reportedErrors.has(error)) {
         unreportedErrors.push(error);
-        reportedErrors.set(error, true);
+        reportedErrors.add(error);
       }
     }