How to Build a GraphQL server with NodeJS and Express

GraphQL is the open-supply question-based language that is used for querying the data. The main task of GraphQL is to execute the given question return the appropriate facts and represent it to the person. GrapghQL is the advancement of conventional REST API architecture presenting greater features. In this newsletter, we are able to see the ste[s to create the Simple GraphQL server. We can even execute the query and based on that query the result might be fetched.

Prerequisites:

• VSCode
• NodeJS
• Express

Steps to create a GraphQL Server with Node & Express

Step 1: Create a New Directory by running the following command on vs code.

mkdir simple-graphql-server
cd simple-graphql-server

Step 2: Initialize the Project using the following command.

npm init -y

Step 3: Install the required dependencies for the project

npm install express express-graphql graphql

Folder Structure:

Folder Structure

The updated dependencies in package.json file will look like:

"dependencies": {
    "express": "^4.18.2",
    "express-graphql": "^0.12.0",
    "graphql": "^15.8.0"
}

Example: Create GraphQL schema in schema.js file and setup it in app.js file.

Javascript

// schema.js

const { GraphQLObjectType, GraphQLString, GraphQLSchema } = require('graphql');
// Defining a simple GraphQL type for articles
const ArticleType = new GraphQLObjectType({
    name: 'Article',
    fields: {
        id: { type: GraphQLString },
        title: { type: GraphQLString },
        content: { type: GraphQLString },
    },
});
// Defining the root query
const RootQuery = new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
        article: {
            type: ArticleType,
            args: { id: { type: GraphQLString } },
            resolve(parent, args) {
                const articleData = {
                    id: args.id,
                    title: 'Introduction to GraphQL',
                    content: 'This is a sample article about GraphQL on GeeksforGeeks.',
                };
                return articleData;
            },
        },
    },
});
// Creating the GraphQL schema
module.exports = new GraphQLSchema({
    query: RootQuery,
});

Javascript

// app.js

const express = require('express');
const { graphqlHTTP } = require('express-graphql');
const schema = require('./schema');
const app = express();
// Setting up the GraphQL endpoint
app.use(
    '/graphql',
    graphqlHTTP({
        schema: schema,
        graphiql: true,
    })
);
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
    console.log(`Server is running on port ${PORT}`);
});

Step to run the application: Run the Server using the following command.

node server.js

Output:

How to test GraphQL Server?

To test the server we will try the following query in the GraphiQL interface

query {
  article(id: "1") {
    id
    title
    content
  }
}

This query has fetched the details for us which are specified in the schema.

Output:

\