React.js data synchronization with GraphQL subscriptions

25 Sep 2023

In a modern web application, real-time updates and data synchronization play a crucial role in delivering a seamless user experience. To achieve these functionalities, you can leverage the power of React.js and GraphQL subscriptions.

What are GraphQL subscriptions?

GraphQL subscriptions allow you to subscribe to specific data within your GraphQL schema and receive updates whenever that data changes on the server. Unlike traditional REST APIs, where you have to continuously poll for updates, GraphQL subscriptions use websockets to establish a persistent connection between the client and server.

Setting up a React.js project with GraphQL subscriptions

To get started, you need to have a React.js project set up with GraphQL integration. If you haven’t already, you can use the create-react-app command to initialize a new project.

npx create-react-app my-app
cd my-app
npm install apollo-client react-apollo subscriptions-transport-ws

Creating a subscription component

Next, you’ll create a component that subscribes to a specific GraphQL subscription. For this example, let’s assume you have a subscription called newPosts that notifies you whenever a new blog post is created.

import React from 'react';
import { Subscription } from 'react-apollo';
import gql from 'graphql-tag';

const NEW_POSTS_SUBSCRIPTION = gql`
  subscription NewPosts {
    newPosts {
      id
      title
      content
    }
  }
`;

const NewPostsSubscription = () => (
  <Subscription subscription={NEW_POSTS_SUBSCRIPTION}>
    {({ data, loading }) => {
      if (loading) return <p>Loading...</p>;

      return (
        <div>
          {data.newPosts.map(post => (
            <div key={post.id}>
              <h3>{post.title}</h3>
              <p>{post.content}</p>
            </div>
          ))}
        </div>
      );
    }}
  </Subscription>
);

export default NewPostsSubscription;

Integrating with Apollo Client

To establish the connection with your GraphQL server using websockets, you need to configure Apollo Client with the appropriate network interface. You’ll also need to install the subscriptions-transport-ws package.

import React from 'react';
import { ApolloProvider } from 'react-apollo';
import ApolloClient from 'apollo-client';
import { HttpLink } from 'apollo-link-http';
import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';
import { InMemoryCache } from 'apollo-cache-inmemory';
import NewPostsSubscription from './NewPostsSubscription';

const httpLink = new HttpLink({
  uri: 'https://your-graphql-server.com/graphql',
});

const wsLink = new WebSocketLink({
  uri: 'wss://your-graphql-server.com/subscriptions',
  options: {
    reconnect: true,
  },
});

const link = split(
  ({ query }) => {
    const { kind, operation } = getMainDefinition(query);
    return kind === 'OperationDefinition' && operation === 'subscription';
  },
  wsLink,
  httpLink,
);

const client = new ApolloClient({
  link,
  cache: new InMemoryCache(),
});

const App = () => (
  <ApolloProvider client={client}>
    <div>
      <h2>New Blog Posts</h2>
      <NewPostsSubscription />
    </div>
  </ApolloProvider>
);

export default App;

Conclusion

By combining React.js with GraphQL subscriptions, you can achieve real-time data synchronization in your web application. This allows you to provide users with up-to-date information and a dynamic user experience. With the power of React.js and GraphQL, you can build highly responsive and interactive applications. #GraphQL #ReactJs