Backend Development Development Tutorials, Guides & Insights

Create a JavaScript file named app.js in your project directory and open it in your preferred code editor.

touch app.js

No preview available for this content.

Ensure that Vite is configured to handle React in your project:

   npm install react react-dom

Start the server by running the following command in your terminal:

go run main.go

const { ApolloServer, gql, PubSub } = require('apollo-server-express');
const pubsub = new PubSub();

const BOOK_ADDED = 'BOOK_ADDED';

const typeDefs = gql`
    type Book {
        title: String!
        author: String!
    }

    type Query {
        books: [Book]
    }

    type Mutation {
        addBook(title: String!, author: String!): Book
    }

    type Subscription {
        bookAdded: Book
    }
`;

const resolvers = {
    Query: {
        books: () => books,
    },
    Mutation: {
        addBook: (_, { title, author }) => {
            const newBook = { title, author };
            books.push(newBook);
            pubsub.publish(BOOK_ADDED, { bookAdded: newBook });
            return newBook;
        },
    },
    Subscription: {
        bookAdded: {
            subscribe: () => pubsub.asyncIterator([BOOK_ADDED]),
        },
    },
};

const server = new ApolloServer({
    typeDefs,
    resolvers,
    subscriptions: {
        path: '/subscriptions',
    },
});

const app = express();
server.applyMiddleware({ app });

const httpServer = require('http').createServer(app);
server.installSubscriptionHandlers(httpServer);

httpServer.listen({ port: 4000 }, () => {
    console.log(`🚀 Server ready at http://localhost:4000${server.graphqlPath}`);
    console.log(`🚀 Subscriptions ready at ws://localhost:4000${server.subscriptionsPath}`);
});

In the GraphQL Playground, you can test the subscription by running the following: