feat: ✨ Initial graphql federation: users application

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+  "cSpell.words": [
+    "nestjs"
+  ]
+}

apps/users-application/src/app/app.module.ts

@@ -2,9 +2,10 @@ import { Module } from '@nestjs/common';
 
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
+import { UsersModule } from '../users/users.module';
 
 @Module({
-  imports: [],
+  imports: [UsersModule],
   controllers: [AppController],
   providers: [AppService],
 })

apps/users-application/src/users/models/user.model.ts

@@ -0,0 +1,11 @@
+import { Directive, Field, ID, ObjectType } from '@nestjs/graphql';
+
+@ObjectType()
+@Directive('@key(fields: "id")')
+export class User {
+  @Field(() => ID)
+  id: number;
+
+  @Field()
+  name: string;
+}

apps/users-application/src/users/users.module.ts

@@ -0,0 +1,30 @@
+import {
+  ApolloFederationDriver,
+  ApolloFederationDriverConfig,
+} from '@nestjs/apollo';
+import { Module } from '@nestjs/common';
+import { GraphQLModule } from '@nestjs/graphql';
+import { UsersResolver } from './users.resolver';
+import { UsersService } from './users.service';
+import { ApolloServerPluginInlineTrace } from '@apollo/server/plugin/inlineTrace';
+
+@Module({
+  providers: [UsersResolver, UsersService],
+  imports: [
+    GraphQLModule.forRoot<ApolloFederationDriverConfig>({
+      driver: ApolloFederationDriver,
+      autoSchemaFile: {
+        /**
+         * MEMO:
+         * Because of this problem, so mush need specify the version
+         * https://github.com/nestjs/graphql/issues/2646#issuecomment-1567381944
+         */
+        federation: 2,
+      },
+      playground: process.env['NODE_ENV'] !== 'production',
+      sortSchema: true,
+      plugins: [ApolloServerPluginInlineTrace()],
+    }),
+  ],
+})
+export class UsersModule {}

apps/users-application/src/users/users.resolver.spec.ts

@@ -0,0 +1,64 @@
+import { Test, TestingModule } from '@nestjs/testing';
+import { UsersResolver } from './users.resolver';
+import { UsersService } from './users.service';
+import { User } from './models/user.model';
+
+describe('UsersResolver', () => {
+  let resolver: UsersResolver;
+  let service: UsersService;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        UsersResolver,
+        {
+          provide: UsersService,
+          useValue: {
+            findById: jest.fn(),
+          },
+        },
+      ],
+    }).compile();
+
+    resolver = module.get<UsersResolver>(UsersResolver);
+    service = module.get<UsersService>(UsersService);
+  });
+
+  it('should be defined', () => {
+    expect(resolver).toBeDefined();
+  });
+
+  describe('getUser', () => {
+    it('should return a user by id', () => {
+      const user: User = { id: 1, name: 'John Doe' };
+      jest.spyOn(service, 'findById').mockReturnValue(user);
+
+      expect(resolver.getUser(1)).toEqual(user);
+      expect(service.findById).toHaveBeenCalledWith(1);
+    });
+
+    it('should return undefined if user not found', () => {
+      jest.spyOn(service, 'findById').mockReturnValue(undefined);
+
+      expect(resolver.getUser(1)).toBeUndefined();
+      expect(service.findById).toHaveBeenCalledWith(1);
+    });
+  });
+
+  describe('resolveReference', () => {
+    it('should return a user by reference id', () => {
+      const user: User = { id: 1, name: 'John Doe' };
+      jest.spyOn(service, 'findById').mockReturnValue(user);
+
+      expect(resolver.resolveReference({ __typename: 'User', id: 1 })).toEqual(user);
+      expect(service.findById).toHaveBeenCalledWith(1);
+    });
+
+    it('should return undefined if user not found by reference id', () => {
+      jest.spyOn(service, 'findById').mockReturnValue(undefined);
+
+      expect(resolver.resolveReference({ __typename: 'User', id: 1 })).toBeUndefined();
+      expect(service.findById).toHaveBeenCalledWith(1);
+    });
+  });
+});

apps/users-application/src/users/users.resolver.ts

@@ -0,0 +1,22 @@
+import { Args, ID, Query, Resolver, ResolveReference } from '@nestjs/graphql';
+
+import { User } from './models/user.model';
+import { UsersService } from './users.service';
+
+@Resolver(() => User)
+export class UsersResolver {
+  constructor(private usersService: UsersService) {}
+
+  @Query(() => User, { nullable: true })
+  getUser(@Args({ name: 'id', type: () => ID }) id: number): User | undefined {
+    return this.usersService.findById(id);
+  }
+
+  @ResolveReference()
+  resolveReference(reference: {
+    __typename: string;
+    id: number;
+  }): User | undefined {
+    return this.usersService.findById(reference.id);
+  }
+}

apps/users-application/src/users/users.service.spec.ts

@@ -0,0 +1,29 @@
+import { Test, TestingModule } from '@nestjs/testing';
+import { UsersService } from './users.service';
+import { User } from './models/user.model';
+
+describe('UsersService', () => {
+  let service: UsersService;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [UsersService],
+    }).compile();
+
+    service = module.get<UsersService>(UsersService);
+  });
+
+  it('should be defined', () => {
+    expect(service).toBeDefined();
+  });
+
+  it('should return a user by id', () => {
+    const user: User = service.findById(1);
+    expect(user).toEqual({ id: 1, name: 'John Doe' });
+  });
+
+  it('should return undefined if user is not found', () => {
+    const user: User = service.findById(3);
+    expect(user).toBeUndefined();
+  });
+});

apps/users-application/src/users/users.service.ts

@@ -0,0 +1,14 @@
+import { Injectable } from '@nestjs/common';
+import { User } from './models/user.model';
+
+@Injectable()
+export class UsersService {
+  private users: User[] = [
+    { id: 1, name: 'John Doe' },
+    { id: 2, name: 'Richard Roe' },
+  ];
+
+  findById(id: number): User | undefined {
+    return this.users.find((user) => user.id === Number(id));
+  }
+}

package.json

@@ -12,17 +12,25 @@
   },
   "private": true,
   "dependencies": {
-    "@nestjs/common": "^10.0.2",
-    "@nestjs/core": "^10.0.2",
-    "@nestjs/platform-express": "^10.0.2",
-    "axios": "^1.6.0",
-    "reflect-metadata": "^0.1.13",
-    "rxjs": "^7.8.0"
+    "@apollo/gateway": "^2.5.5",
+    "@apollo/server": "^4.11.2",
+    "@apollo/subgraph": "^2.5.5",
+    "@nestjs/apollo": "^12.2.1",
+    "@nestjs/common": "^10.4.7",
+    "@nestjs/core": "^10.4.7",
+    "@nestjs/graphql": "^12.2.1",
+    "@nestjs/platform-express": "^10.4.7",
+    "axios": "^1.7.7",
+    "graphql": "^16.9.0",
+    "graphql-tools": "^9.0.2",
+    "inlineTrace": "link:@apollo/server/plugin/inlineTrace",
+    "reflect-metadata": "^0.1.14",
+    "rxjs": "^7.8.1"
   },
   "devDependencies": {
-    "@eslint/js": "^9.8.0",
-    "@nestjs/schematics": "^10.0.1",
-    "@nestjs/testing": "^10.0.2",
+    "@eslint/js": "^9.14.0",
+    "@nestjs/schematics": "^10.2.3",
+    "@nestjs/testing": "^10.4.7",
     "@nx/eslint": "20.0.6",
     "@nx/eslint-plugin": "20.0.6",
     "@nx/jest": "20.0.6",
@@ -32,24 +40,24 @@
     "@nx/web": "20.0.6",
     "@nx/webpack": "20.0.6",
     "@nx/workspace": "20.0.6",
-    "@swc-node/register": "~1.9.1",
-    "@swc/core": "~1.5.7",
-    "@swc/helpers": "~0.5.11",
-    "@types/jest": "^29.5.12",
+    "@swc-node/register": "~1.9.2",
+    "@swc/core": "~1.5.29",
+    "@swc/helpers": "~0.5.13",
+    "@types/jest": "^29.5.14",
     "@types/node": "~22.9.0",
-    "@zhumeisong/git-cz-config": "^1.1.1",
-    "eslint": "^9.8.0",
-    "eslint-config-prettier": "^9.0.0",
+    "@zhumeisong/git-cz-config": "^1.2.0",
+    "eslint": "^9.14.0",
+    "eslint-config-prettier": "^9.1.0",
     "git-cz": "^4.9.0",
     "jest": "^29.7.0",
     "jest-environment-node": "^29.7.0",
     "nx": "20.0.6",
-    "prettier": "^3.0.0",
-    "ts-jest": "^29.1.0",
+    "prettier": "^2.8.8",
+    "ts-jest": "^29.2.5",
     "ts-node": "10.9.1",
-    "tslib": "^2.3.0",
-    "typescript": "~5.5.2",
-    "typescript-eslint": "^8.0.0",
+    "tslib": "^2.8.1",
+    "typescript": "~5.5.4",
+    "typescript-eslint": "^8.13.0",
     "webpack-cli": "^5.1.4"
   },
   "packageManager": "[email protected]",