GraphQL API Server with Node.js and Apollo Server

This snippet demonstrates how to set up a basic GraphQL server using Apollo Server and Express in Node.js. The server will expose a simple API for managing a list of books.

Setting Up the Server

• Initialize the Project

First, create a new directory for your project and initialize it with npm:

mkdir graphql-server
   cd graphql-server
   npm init -y
   

• Install Dependencies

Install the required packages:

npm install express apollo-server-express graphql
   

• Create the Server Code

Create an index.js file and add the following code:

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

// Sample data
let books = [
    { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' },
    { title: 'To Kill a Mockingbird', author: 'Harper Lee' },
];

// GraphQL schema definition
const typeDefs = gql`
    type Book {
        title: String!
        author: String!
    }

    type Query {
        books: [Book]
    }

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

// GraphQL resolvers
const resolvers = {
    Query: {
        books: () => books,
    },
    Mutation: {
        addBook: (_, { title, author }) => {
            const newBook = { title, author };
            books.push(newBook);
            return newBook;
        },
    },
};

// Create Apollo server
const server = new ApolloServer({ typeDefs, resolvers });

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

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

Features of the GraphQL Server

• Schema Definition: The typeDefs defines a simple schema with a Book type and queries to fetch books and add a new book.

• Resolvers: Functions that resolve the queries and mutations. In this case, they return all books and add a new book to the list.

How to Use

• Start the Server

Run the server using Node.js:

node index.js
   

• Access the GraphQL Playground

Open a browser and go to http://localhost:4000/graphql. You'll see the Apollo GraphQL Playground, where you can test your queries and mutations.

• Example Queries

- Fetch Books

query {
       books {
         title
         author
       }
     }
     

- Add a Book

mutation {
       addBook(title: "1984", author: "George Orwell") {
         title
         author
       }
     }
     

Benefits of GraphQL

• Flexible Queries: Allows clients to request only the data they need, reducing over-fetching.

• Strongly Typed: Ensures data consistency and helps with error handling.

• Single Endpoint: All data operations occur through a single endpoint, simplifying network requests.