0Pricing
Node.js Backend Development Bootcamp · Lesson

Building a GraphQL Server with Apollo

Implement a GraphQL API in Node.js using Apollo Server, connecting it to your data sources and defining resolvers.

Building a GraphQL Server with Apollo is a free Node.js Backend Development Bootcamp lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Node.js Backend Development Bootcamp learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Meet Apollo Server

Welcome to building a GraphQL server! We'll use Apollo Server, a popular open-source library that helps you implement a production-ready GraphQL API in Node.js.

  • It's easy to set up.
  • It integrates with many Node.js frameworks like Express.
  • It provides powerful tools like GraphQL Playground for testing.

Apollo Server handles the heavy lifting, letting you focus on your data.

Building a GraphQL Server with Apollo — illustration 1

Project Setup for Apollo

Let's get started by setting up our project. Open your terminal and run these commands to create a new Node.js project and install the required libraries:

  • apollo-server: The core library for building our GraphQL server.
  • graphql: The JavaScript implementation of the GraphQL specification.

Here's how to do it:

mkdir my-graphql-api
cd my-graphql-api
npm init -y
npm install apollo-server graphql

Once installed, you're ready to write some code!

Schema & Resolvers: The Core

A GraphQL server has two main parts:

  • Schema (Type Definitions): This defines the shape of your data and the operations clients can perform (queries, mutations). Think of it as the contract between client and server.
  • Resolvers: These are functions that tell GraphQL how to fetch the data for each type and field defined in your schema. They are the "backend logic" for your API.

Together, they define your API's capabilities and how it interacts with your data.

Crafting Your GraphQL Schema

We define the schema using a special template literal tag called gql (from apollo-server). This allows us to write GraphQL Schema Definition Language (SDL).

The most important type is Query, which defines all the ways clients can read data from your API. Let's define a simple Query that returns a "hello" message.

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

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

console.log('Your schema is ready!');

Building Your Resolvers

Now that we have our schema, we need to tell GraphQL how to actually get the data for the hello field. This is where resolvers come in.

Resolvers are functions that match the fields in your schema. When a client queries hello, the corresponding resolver function will be executed.

const resolvers = {
  Query: {
    hello: () => 'Hello from your GraphQL API!',
  },
};

console.log('Resolvers are defined!');

Launching Your First Server

Let's put it all together! We'll combine the typeDefs and resolvers with ApolloServer to create a complete, runnable GraphQL server.

Create a file named index.js and add the following code. Then, run it with node index.js.

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

// 1. Define your schema (type definitions)
const typeDefs = gql`
  type Query {
    hello: String
  }
`;

// 2. Define your resolvers (how to fetch data)
const resolvers = {
  Query: {
    hello: () => 'Hello from your GraphQL API!',
  },
};

// 3. Create an Apollo Server instance
const server = new ApolloServer({ typeDefs, resolvers });

// 4. Start the server
server.listen({ port: 4000 }).then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
  console.log('Try opening your browser to test it!');
});

Defining Custom Data Types

A simple "hello" isn't very exciting. Let's define a custom type, like Book, with its own fields. This shows how you structure more complex data.

Update your typeDefs to include the Book type and a books query that returns a list of them.

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

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

  type Query {
    hello: String
    books: [Book]
  }
`;

console.log('Schema updated with Book type!');

Resolving Custom Types

To make the books query work, we need to update our resolvers. For now, we'll use an in-memory array of objects to simulate a database. In real applications, resolvers connect to databases or other APIs.

Let's update the resolvers to provide data for our books query.

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

const resolvers = {
  Query: {
    hello: () => 'Hello from your GraphQL API!',
    books: () => books,
  },
};

console.log('Resolvers updated for books!');

Full API with Books

Here's the complete index.js file with our new Book type and its resolver. Run this with node index.js.

Once running, open the URL in your browser (e.g., http://localhost:4000). You'll see the GraphQL Playground, where you can test queries like:

query {
  books {
    title
    author
  }
}

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

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

  type Query {
    hello: String
    books: [Book]
  }
`;

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

const resolvers = {
  Query: {
    hello: () => 'Hello from your GraphQL API!',
    books: () => books,
  },
};

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

server.listen({ port: 4000 }).then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
  console.log('Explore your API in GraphQL Playground!');
});

Schema vs. Resolvers Check

You've learned about the two fundamental parts of a GraphQL server: the schema (type definitions) and the resolvers.

Which of the following best describes the primary role of GraphQL Resolvers in an Apollo Server?

Apollo Server: Quick Recap

Great job! You've successfully built your first GraphQL server with Apollo Server.

  • We installed apollo-server and graphql.
  • We defined our API's structure using Type Definitions (typeDefs) written in GraphQL SDL.
  • We implemented Resolvers to specify how to fetch data for the fields in our schema, using mock data.
  • We launched our server using ApolloServer and explored it with GraphQL Playground.

This is the foundation for building powerful and flexible GraphQL APIs. Next, you can explore mutations, arguments, and connecting to real databases!

Frequently asked questions

Is the “Building a GraphQL Server with Apollo” lesson free?

Yes — the full text of “Building a GraphQL Server with Apollo” is free to read here on the web, and the Node.js Backend Development Bootcamp course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Node.js Backend Development Bootcamp course, upgrade to CoddyKit PRO.

What will I learn in “Building a GraphQL Server with Apollo”?

Implement a GraphQL API in Node.js using Apollo Server, connecting it to your data sources and defining resolvers. You practise Node.js Backend Development Bootcamp with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Node.js Backend Development Bootcamp?

No prior experience is required. Node.js Backend Development Bootcamp on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Building a GraphQL Server with Apollo” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Node.js Backend Development Bootcamp lesson?

Yes. Every Node.js Backend Development Bootcamp lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Introduction to Serverless with Node.js
  2. GraphQL API Design Principles
  3. Building a GraphQL Server with Apollo
  4. GraphQL Subscriptions for Real-Time Data
← Back to Node.js Backend Development Bootcamp