apollo_graphql_federation_subgraph_service_quickstart.ts

1import { ApolloServer } from '@apollo/server';
2import { startStandaloneServer } from '@apollo/server/standalone';
3import { buildSubgraphSchema } from '@apollo/subgraph';
4import { gql } from 'graphql-tag';
5
6// 1. Define your GraphQL schema
7const typeDefs = gql`
8  extend schema
9    @link(url: "https://specs.apollo.dev/federation/v2.0",
10          import: ["@key"])
11
12  type Query {
13    me: User
14  }
15
16  type User @key(fields: "id") {
17    id: ID!
18    username: String
19  }
20`;
21
22// 2. Define your resolvers
23const resolvers = {
24  Query: {
25    me() {
26      return { id: "1", username: "@ada" };
27    },
28  },
29  User: {
30    __resolveReference(user: { id: string }) {
31      // This fetch is where you'd look up the user by id in a real DB
32      return { id: user.id, username: "@ada" };
33    },
34  },
35};
36
37// 3. Build the federated schema
38const schema = buildSubgraphSchema({ typeDefs, resolvers });
39
40// 4. Initialize and start the server
41const server = new ApolloServer({
42  schema,
43});
44
45const { url } = await startStandaloneServer(server, {
46  listen: { port: 4001 },
47});
48
49console.log(`🚀 Subgraph ready at ${url}`);