fix(federation): handle shared root fields (#552)

graphql-hive · Jan 29, 2025 · b0bc26b · b0bc26b
1 parent 180c2c4
commit b0bc26b
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Showing 5 changed files with 317 additions and 29 deletions.
diff --git a/.changeset/tiny-rivers-build.md b/.changeset/tiny-rivers-build.md
@@ -0,0 +1,8 @@
+---
+'@graphql-tools/federation': patch
+---
+
+Handle shared subscription root fields correctly
+
+In case of conflicting subscription root fields coming from different subgraphs or different entry points(multiple keys),
+subscription was failing.
diff --git a/packages/federation/src/supergraph.ts b/packages/federation/src/supergraph.ts
@@ -41,6 +41,7 @@ import {
   EnumValueDefinitionNode,
   FieldDefinitionNode,
   FieldNode,
+  GraphQLFieldResolver,
   GraphQLInterfaceType,
   GraphQLOutputType,
   GraphQLSchema,
@@ -1216,9 +1217,8 @@ export function getStitchingOptionsFromSupergraphSdl(
     }
     if (operationType) {
       const defaultMergedField = defaultMerger(candidates);
-      return {
-        ...defaultMergedField,
-        resolve(_root, _args, context, info) {
+      const mergedResolver: GraphQLFieldResolver<{}, {}> =
+        function mergedResolver(_root, _args, context, info) {
           const originalSelectionSet: SelectionSetNode = {
             kind: Kind.SELECTION_SET,
             selections: info.fieldNodes,
@@ -1361,7 +1361,19 @@ export function getStitchingOptionsFromSupergraphSdl(
             return Promise.all(jobs).then((results) => mergeResults(results));
           }
           return mergeResults(jobs);
-        },
+        };
+      if (operationType === 'subscription') {
+        return {
+          ...defaultMergedField,
+          subscribe: mergedResolver,
+          resolve: function identityFn(payload) {
+            return payload;
+          },
+        };
+      }
+      return {
+        ...defaultMergedField,
+        resolve: mergedResolver,
       };
     }
     const filteredCandidates = candidates.filter((candidate) => {

diff --git a/packages/federation/tests/getStitchedSchemaFromLocalSchemas.ts b/packages/federation/tests/getStitchedSchemaFromLocalSchemas.ts
@@ -2,9 +2,11 @@ import { createDefaultExecutor } from '@graphql-tools/delegate';
 import {
   ExecutionRequest,
   ExecutionResult,
+  getDocumentNodeFromSchema,
   mapMaybePromise,
 } from '@graphql-tools/utils';
 import { composeLocalSchemasWithApollo } from '@internal/testing';
+import { composeServices } from '@theguild/federation-composition';
 import { GraphQLSchema } from 'graphql';
 import { kebabCase } from 'lodash';
 import { getStitchedSchemaFromSupergraphSdl } from '../src/supergraph';
@@ -14,21 +16,49 @@ export interface LocalSchemaItem {
   schema: GraphQLSchema;
 }
 
-export async function getStitchedSchemaFromLocalSchemas(
-  localSchemas: Record<string, GraphQLSchema>,
+export async function getStitchedSchemaFromLocalSchemas({
+  localSchemas,
+  onSubgraphExecute,
+  composeWith = 'apollo',
+  ignoreRules,
+}: {
+  localSchemas: Record<string, GraphQLSchema>;
   onSubgraphExecute?: (
     subgraph: string,
     executionRequest: ExecutionRequest,
     result: ExecutionResult | AsyncIterable<ExecutionResult>,
-  ) => void,
-): Promise<GraphQLSchema> {
-  const supergraphSdl = await composeLocalSchemasWithApollo(
-    Object.entries(localSchemas).map(([name, schema]) => ({
-      name,
-      schema,
-      url: `http://localhost/${name}`,
-    })),
-  );
+  ) => void;
+  composeWith?: 'apollo' | 'guild';
+  ignoreRules?: string[];
+}): Promise<GraphQLSchema> {
+  let supergraphSdl: string;
+  if (composeWith === 'apollo') {
+    supergraphSdl = await composeLocalSchemasWithApollo(
+      Object.entries(localSchemas).map(([name, schema]) => ({
+        name,
+        schema,
+        url: `http://localhost/${name}`,
+      })),
+    );
+  } else if (composeWith === 'guild') {
+    const result = composeServices(
+      Object.entries(localSchemas).map(([name, schema]) => ({
+        name,
+        typeDefs: getDocumentNodeFromSchema(schema),
+        url: `http://localhost/${name}`,
+      })),
+      { disableValidationRules: ignoreRules },
+    );
+    result.errors?.forEach((error) => {
+      console.error(error);
+    });
+    if (!result.supergraphSdl) {
+      throw new Error('Failed to compose services');
+    }
+    supergraphSdl = result.supergraphSdl;
+  } else {
+    throw new Error(`Unknown composeWith ${composeWith}`);
+  }
   function createTracedExecutor(name: string, schema: GraphQLSchema) {
     const executor = createDefaultExecutor(schema);
     return function tracedExecutor(request: ExecutionRequest) {

diff --git a/packages/federation/tests/optimizations.test.ts b/packages/federation/tests/optimizations.test.ts
@@ -630,15 +630,15 @@ it('nested recursive requirements', async () => {
 
   const subgraphCalls: Record<string, number> = {};
 
-  const schema = await getStitchedSchemaFromLocalSchemas(
-    {
+  const schema = await getStitchedSchemaFromLocalSchemas({
+    localSchemas: {
       inventory,
       spatial,
     },
-    (subgraph) => {
+    onSubgraphExecute: (subgraph) => {
       subgraphCalls[subgraph] = (subgraphCalls[subgraph] || 0) + 1;
     },
-  );
+  });
 
   expect(
     await normalizedExecutor({