docs(federation): add federation and gateway example

Author: MichalLytek

examples/4-federation/Readme.md

@@ -0,0 +1,16 @@
+## Apollo Federation
+
+Showcase of Apollo Federation approach, using the `TypeGraphQLFederationModule` and `GraphQLGatewayModule`.
+
+### How to run?
+
+This example is a bit more complex than the other ones.
+
+Apart from running the main `index.ts` file by e.g. `npx ts-node ./examples/4-federation/index.ts`, you also need to run all the other services first:
+
+- `npx ts-node ./examples/4-federation/accounts/index.ts`
+- `npx ts-node ./examples/4-federation/inventory/index.ts`
+- `npx ts-node ./examples/4-federation/products/index.ts`
+- `npx ts-node ./examples/4-federation/reviews/index.ts`
+
+They will be listening on ports 3001-3004 and the main script on port 3000.

examples/4-federation/accounts/account.module.ts

@@ -0,0 +1,21 @@
+import { Module } from "@nestjs/common";
+import { TypeGraphQLFederationModule } from "../../../src";
+
+import AccountsResolver from "./resolver";
+import User from "./user";
+import { resolveUserReference } from "./user-reference";
+
+@Module({
+  imports: [
+    TypeGraphQLFederationModule.forFeature({
+      orphanedTypes: [User],
+      referenceResolvers: {
+        User: {
+          __resolveReference: resolveUserReference,
+        },
+      },
+    }),
+  ],
+  providers: [AccountsResolver],
+})
+export default class AccountModule {}

examples/4-federation/accounts/app.module.ts

@@ -0,0 +1,15 @@
+import { Module } from "@nestjs/common";
+import { TypeGraphQLFederationModule } from "../../../src";
+
+import AccountModule from "./account.module";
+
+@Module({
+  imports: [
+    TypeGraphQLFederationModule.forRoot({
+      validate: false,
+      skipCheck: true,
+    }),
+    AccountModule,
+  ],
+})
+export default class AppModule {}

examples/4-federation/accounts/data.ts

@@ -0,0 +1,20 @@
+import User from "./user";
+
+export const users: User[] = [
+  createUser({
+    id: "1",
+    name: "Ada Lovelace",
+    birthDate: "1815-12-10",
+    username: "@ada",
+  }),
+  createUser({
+    id: "2",
+    name: "Alan Turing",
+    birthDate: "1912-06-23",
+    username: "@complete",
+  }),
+];
+
+function createUser(userData: Partial<User>) {
+  return Object.assign(new User(), userData);
+}

examples/4-federation/accounts/index.ts

@@ -0,0 +1,19 @@
+import "reflect-metadata";
+import { NestFactory } from "@nestjs/core";
+import {
+  NestFastifyApplication,
+  FastifyAdapter,
+} from "@nestjs/platform-fastify";
+
+import AppModule from "./app.module";
+
+async function bootstrap() {
+  const app = await NestFactory.create<NestFastifyApplication>(
+    AppModule,
+    new FastifyAdapter(),
+  );
+
+  await app.listen(3001);
+}
+
+bootstrap();

examples/4-federation/accounts/resolver.ts

@@ -0,0 +1,12 @@
+import { Resolver, Query } from "type-graphql";
+
+import User from "./user";
+import { users } from "./data";
+
+@Resolver(of => User)
+export default class AccountsResolver {
+  @Query(returns => User)
+  me(): User {
+    return users[0];
+  }
+}

examples/4-federation/accounts/user-reference.ts

@@ -0,0 +1,6 @@
+import { users } from "./data";
+import User from "./user";
+
+export async function resolveUserReference(reference: Pick<User, "id">): Promise<User> {
+  return users.find(u => u.id === reference.id)!;
+}

examples/4-federation/accounts/user.ts

@@ -0,0 +1,17 @@
+import { Field, ObjectType, Directive, ID } from "type-graphql";
+
+@Directive(`@key(fields: "id")`)
+@ObjectType()
+export default class User {
+  @Field(type => ID)
+  id!: string;
+
+  @Field()
+  username!: string;
+
+  @Field()
+  name!: string;
+
+  @Field()
+  birthDate!: string;
+}

examples/4-federation/app.module.ts

@@ -0,0 +1,24 @@
+import "reflect-metadata";
+
+import { Module } from "@nestjs/common";
+import { GraphQLGatewayModule } from "@nestjs/graphql";
+
+@Module({
+  imports: [
+    GraphQLGatewayModule.forRoot({
+      server: {
+        tracing: true,
+        playground: true,
+      },
+      gateway: {
+        serviceList: [
+          { name: "accounts", url: "http://localhost:3001/graphql" },
+          { name: "inventory", url: "http://localhost:3002/graphql" },
+          { name: "products", url: "http://localhost:3003/graphql" },
+          { name: "reviews", url: "http://localhost:3004/graphql" },
+        ],
+      },
+    }),
+  ],
+})
+export default class AppModule {}

examples/4-federation/examples.graphql

@@ -0,0 +1,20 @@
+query {
+  topProducts {
+    name
+    price
+    shippingEstimate
+    inStock
+    reviews {
+      body
+      author {
+        name
+        birthDate
+        reviews {
+          product {
+            name
+          }
+        }
+      }
+    }
+  }
+}