Using GraphQL with Node.js (e.g., Apollo Server)
Published: 2024-06-05 15:10:03

# Using GraphQL with Node.js (e.g., Apollo Server)

GraphQL is a powerful query language for APIs that was developed by Facebook. It provides a more efficient and flexible way to retrieve data compared to traditional RESTful APIs. In this guide, we will explore how to use GraphQL with Node.js, specifically focusing on the popular library called Apollo Server.

## Prerequisites

Before diving into the details of using GraphQL with Node.js, make sure you have the following prerequisites installed:

- [Node.js](https://nodejs.org) version 12 or above.
- A code editor of your choice, such as [Visual Studio Code](https://code.visualstudio.com).

## Setting up a new project

To begin using GraphQL with Node.js, start by setting up a new project:

1. Create a new directory for your project and navigate into it:
```bash
$ mkdir my-project
$ cd my-project
```

2. Initialize a new npm package in your project directory:
```bash
$ npm init -y
```

3. Install the required dependencies:
```bash
$ npm install apollo-server graphql
```

## Creating an Apollo Server instance

Once you have set up your project and installed the necessary dependencies, it's time to create an instance of Apollo Server:

1. Open your text editor and create a new file named `server.js`.

2. Import the required modules at the top of `server.js`:
```javascript
const { ApolloServer } = require('apollo-server');
const typeDefs = require('./schema'); // We'll define this later.
const resolvers = require('./resolvers'); // We'll define this later.
```

3. Define the configuration options for your server below the imports:
```javascript
const server = new ApolloServer({
  typeDefs,
  resolvers,
});
```
4. Start listening for incoming requests after defining configuration options:
```javascript
server.listen().then(({ url }) => {
  console.log(`Server ready at ${url}`);
});
```

## Defining GraphQL Schema

To define the schema for your GraphQL API, create a new file named `schema.js`:

1. In your preferred text editor, create a new file named `schema.js`.

2. Define your schema using the [GraphQL SDL](https://graphql.org/learn/schema/) syntax in `schema.js`. Here's an example:
```graphql
type Query {
  hello: String
}

type Mutation {
  updateHello(message: String!): String
}
```

## Implementing Resolvers

Resolvers are responsible for resolving requests made to different fields in your schema. Create a new file named `resolvers.js`:

1. In your text editor, create a new file named `resolvers.js`.

2. Implement resolver functions corresponding to each field defined in the schema. Here's an example:
```javascript
const resolvers = {
  Query: {
    hello: () => 'Hello from Apollo Server!',
  },
  Mutation: {
    updateHello: (_, { message }) => {
      // Perform some logic or database operations here.
      return message;
    },
  },
};

module.exports = resolvers;
```

## Starting the server

With everything set up, it's time to start the Apollo Server:

1. Open a terminal window and navigate to the root directory of your project.

2. Run the following command to start the server:
```bash
$ node server.js
```

3. You should see a log message indicating that the server is ready and listening on a port.

4. Open any web browser and visit [http://localhost:[PORT]/graphql](http://localhost:[PORT]/graphql). Replace `[PORT]` with the actual port number provided by Apollo Server.

Congratulations! You have successfully created an instance of Apollo Server and implemented basic resolvers for your GraphQL schema. You can now start exploring the powerful capabilities of GraphQL with Node.js.

Feel free to check out the official documentation of [Apollo Server](https://www.apollographql.com/docs/apollo-server/) and [GraphQL](https://graphql.org/) for more detailed information on advanced topics and best practices. Happy coding!