
  Building Real-Time Applications with GraphQL Subscriptions and React
  
    Have you ever wanted to build a web application that can update in real-time, without the user having to refresh the page? With GraphQL subscriptions and React, you can do just that! In this tutorial, we'll show you how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app. By the end of this article, you'll be able to build real-time web applications with ease.
  
  What are GraphQL Subscriptions?
  
    GraphQL is a query language for APIs, and it allows you to build APIs in a way that's flexible and powerful. One of the features that GraphQL provides is subscriptions. Subscriptions are a way to receive real-time updates from an API whenever data changes. With subscriptions, you can build web applications that update in real-time, just like a chat application or a stock ticker.
  
  
    GraphQL subscriptions work by creating a long-lived connection between the client and server. Whenever data changes on the server, it sends a message to all connected clients, and the clients can update their UI accordingly. This is different from a traditional REST API, where the client has to make repeated requests to get the latest data.
  
  
    Now that we have a basic understanding of GraphQL subscriptions, let's dive into building a real-time web application with React and GraphQL subscriptions.
  
  Setting up GraphQL Subscriptions on the Server Side
  
    Before we can use GraphQL subscriptions in our React app, we need to set them up on the server side. In this tutorial, we'll be using Apollo Server and MongoDB.
  
  
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  
  $ npm install apollo-server graphql mongoose
  
    Next, create a new file called index.js and add the following code:
  
  // index.js
const { ApolloServer, PubSub } = require('apollo-server');
const mongoose = require('mongoose');
const typeDefs = require('./typeDefs');
const resolvers = require('./resolvers');

mongoose.connect('mongodb://localhost:27017/myapp', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true
}).then(() =&gt; {
  console.log('MongoDB connected');
}).catch((error) =&gt; {
  console.log(error);
});

const pubsub = new PubSub();

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req }) =&gt; ({ req, pubsub })
});

server.listen().then(({ url }) =&gt; {
  console.log(`Server listening on ${url}`);
});
  
  
    Let's go through this code step by step. First, we import the necessary dependencies: ApolloServer, PubSub, mongoose, and our own typeDefs and resolvers.
  
  
    Next, we connect to our MongoDB database using mongoose.connect. Make sure to replace myapp with your own database name.
  
  
    We then create a new instance of PubSub, which is used to publish and subscribe to messages.
  
  
    After that, we create a new instance of ApolloServer and pass in our typeDefs, resolvers, and a context object. The context object is where we can pass in any values that we want to make available to our resolvers. In this case, we're passing in req (the current request object) and pubsub (our instance of PubSub).
  
  
    Finally, we start the server and log the URL that it's running on. Our server is now ready to handle GraphQL queries and subscriptions!
  
  Creating the GraphQL Schema
  
    Now that we have our server set up, let's create our GraphQL schema. In this tutorial, we'll be building a simple chat application. We'll have a Message type that represents a message, and a Query, Mutation, and Subscription that allow us to retrieve, create, and subscribe to messages, respectively.
  
  
    Create a new folder called schema, and inside that folder, create a new file called message.js. Add the following code:
  
  // schema/message.js
const { gql } = require('apollo-server');

const typeDefs = gql`
  type Message {
    id: ID!
    text: String!
  }

  type Query {
    messages: [Message]!
  }

  type Mutation {
    addMessage(text: String!): Message!
  }

  type Subscription {
    newMessage: Message!
  }
`;

module.exports = typeDefs;
  
  
    Let's go through this code step by step. First, we import gql from apollo-server.
  
  
    We then define a Message type with two fields: id (an ID) and text (a string).
  
  
    Next, we define a Query type with one field: messages (an array of Message objects).
  
  
    We then define a Mutation type with one field: addMessage (which takes a text argument and returns a Message object).
  
  
    Finally, we define a Subscription type with one field: newMessage (which returns a Message object).
  
  
    We export our schema using module.exports. That's it for our schema!
  
  Creating the Resolvers
  
    Next, let's create our resolvers. Resolvers are functions that handle GraphQL queries, mutations, and subscriptions.
  
  
    Create a new folder called resolvers, and inside that folder, create a new file called message.js. Add the following code:
  
  // resolvers/message.js
const Message = require('../models/Message');
const { PubSub } = require('apollo-server');

const pubsub = new PubSub();

const MESSAGE_ADDED = 'MESSAGE_ADDED';

const resolvers = {
  Query: {
    messages: async () =&gt; {
      const messages = await Message.find().sort({ createdAt: -1 });
      return messages;
    }
  },
  Mutation: {
    addMessage: async (_, { text }) =&gt; {
      const newMessage = new Message({
        text
      });
      const message = await newMessage.save();
      pubsub.publish(MESSAGE_ADDED, { newMessage: message });
      return message;
    }
  },
  Subscription: {
    newMessage: {
      subscribe: () =&gt; pubsub.asyncIterator([MESSAGE_ADDED])
    }
  }
};

module.exports = resolvers;
  
  
    Let's go through this code step by step. First, we import our Message model and PubSub from apollo-server.
  
  
    We then create a new instance of PubSub. This is the same instance that we passed to our Apollo Server earlier.
  
  
    Next, we define a constant called MESSAGE_ADDED that we'll use as the topic for our subscription.
  
  
    We then define our resolvers. First, we have a Query resolver for messages, which returns an array of messages sorted by their createdAt date in descending order.
  
  
    Next, we have a Mutation resolver for addMessage, which takes a text argument and creates a new message in our MongoDB database. We then publish a message to our MESSAGE_ADDED topic using pubsub.publish, and return the newly created message.
  
  
    Finally, we have a Subscription resolver for newMessage, which uses pubsub.asyncIterator to subscribe to our MESSAGE_ADDED topic and return any new messages that are published. This resolver has to return an async iterator, which is what allows it to receive real-time updates.
  
  
    We export our resolvers using module.exports. That's it for our resolvers!
  
  Connecting to the GraphQL API from a React Application
  
    Now that our GraphQL API is set up, let's connect to it from our React application. In this tutorial, we'll be using the Apollo Client to do this.
  
  
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  
  $ npm install apollo-boost @apollo/react-hooks subscriptions-transport-ws
  
    apollo-boost is a package that provides a pre-configured Apollo Client, @apollo/react-hooks is a package that provides hooks to use with the Apollo Client, and subscriptions-transport-ws is a package that provides WebSocket support for subscriptions.
  
  
    Next, create a new file called index.js in your React app's src folder, and add the following code:
  
  // src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloProvider } from '@apollo/react-hooks';
import { ApolloClient } from 'apollo-client';
import { HttpLink } from 'apollo-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';
import App from './App';

const httpLink = new HttpLink({
  uri: 'http://localhost:4000/graphql'
});

const wsLink = new WebSocketLink({
  uri: 'ws://localhost:4000/graphql',
  options: {
    reconnect: true
  }
});

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

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

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  
  
    Let's go through this code step by step. First, we import the necessary dependencies. We're using the WebSocketLink from apollo-link-ws to handle WebSocket subscriptions, and we're using the split function from apollo-link and the getMainDefinition function from apollo-utilities to split our link and send subscriptions over the WebSocketLink and everything else over the HttpLink.
  
  
    Next, we create a new instance of HttpLink with the URL of our GraphQL API.
  
  
    We then create a new instance of WebSocketLink with the WebSocket URL of our GraphQL API, and set the reconnect option to true so that the client automatically reconnects if it loses the WebSocket connection.
  
  
    Next, we create a new link using split that decides whether to use the WebSocketLink or HttpLink based on the type of operation being performed. If it's a subscription, we use the WebSocketLink; if it's anything else, we use the HttpLink.
  
  
    Finally, we create a new instance of ApolloClient with our link and an InMemoryCache, and wrap our App component in an ApolloProvider that passes the client down to all child components.
  
  
    Our React application is now connected to our GraphQL API using the Apollo Client!
  
  Using GraphQL Subscriptions in React
  
    Now that we have our React app connected to our GraphQL API, let's use GraphQL subscriptions to receive real-time updates whenever a new message is added.
  
  
    Create a new file called Chat.js in your React app's src folder, and add the following code:
  
  // src/Chat.js
import React, { useState } from 'react';
import { useSubscription, useMutation } from '@apollo/react-hooks';
import { gql } from 'apollo-boost';

const MESSAGES_QUERY = gql`
  {
    messages {
      id
      text
    }
  }
`;

const MESSAGE_ADDED_SUBSCRIPTION = gql`
  subscription {
    newMessage {
      id
      text
    }
  }
`;

const ADD_MESSAGE_MUTATION = gql`
  mutation AddMessage($text: String!) {
    addMessage(text: $text) {
      id
      text
    }
  }
`;

function Chat() {
  const [text, setText] = useState('');
  const [addMessage] = useMutation(ADD_MESSAGE_MUTATION);

  const sendChatMessage = () =&gt; {
    addMessage({
      variables: {
        text: text
      },
      optimisticResponse: {
        addMessage: {
          __typename: 'Message',
          id: -1,
          text: text
        }
      },
      update: (proxy, { data: { addMessage } }) =&gt; {
        const data = proxy.readQuery({ query: MESSAGES_QUERY });
        data.messages.unshift(addMessage);
        proxy.writeQuery({ query: MESSAGES_QUERY, data });
      }
    });

    setText('');
  };

  const { loading, error, data } = useSubscription(
    MESSAGE_ADDED_SUBSCRIPTION
  );

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error: {error.message}&lt;/p&gt;;

  return (
    &lt;div&gt;
      &lt;ul&gt;
        {data.messages.map(message =&gt; (
          &lt;li key={message.id}&gt;{message.text}&lt;/li&gt;
        ))}
      &lt;/ul&gt;
      &lt;div&gt;
        &lt;input type="text" value={text} onChange={e =&gt; setText(e.target.value)} /&gt;
        &lt;button onClick={sendChatMessage}&gt;Send&lt;/button&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  );
}

export default Chat;
  
  
    Let's go through this code step by step. First, we define our MESSAGES_QUERY, which retrieves an array of messages, and our MESSAGE_ADDED_SUBSCRIPTION, which subscribes to new messages.
  
  
    We then define our ADD_MESSAGE_MUTATION, which takes a text argument and creates a new message in our MongoDB database. We're also using optimisticResponse to optimistically update the UI before the server responds, and update to update the cache with the newly created message.
  
  
    We then define our <

<div>
  <h1>Building Real-Time Applications with GraphQL Subscriptions and React</h1>
  <p>
    Have you ever wanted to build a web application that can update in real-time, without the user having to refresh the page? With GraphQL subscriptions and React, you can do just that! In this tutorial, we'll show you how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app. By the end of this article, you'll be able to build real-time web applications with ease.
  </p>
  <h2>What are GraphQL Subscriptions?</h2>
  <p>
    GraphQL is a query language for APIs, and it allows you to build APIs in a way that's flexible and powerful. One of the features that GraphQL provides is subscriptions. Subscriptions are a way to receive real-time updates from an API whenever data changes. With subscriptions, you can build web applications that update in real-time, just like a chat application or a stock ticker.
  </p>
  <p>
    GraphQL subscriptions work by creating a long-lived connection between the client and server. Whenever data changes on the server, it sends a message to all connected clients, and the clients can update their UI accordingly. This is different from a traditional REST API, where the client has to make repeated requests to get the latest data.
  </p>
  <p>
    Now that we have a basic understanding of GraphQL subscriptions, let's dive into building a real-time web application with React and GraphQL subscriptions.
  </p>
  <h2>Setting up GraphQL Subscriptions on the Server Side</h2>
  <p>
    Before we can use GraphQL subscriptions in our React app, we need to set them up on the server side. In this tutorial, we'll be using <a href="https://www.apollographql.com/">Apollo Server</a> and <a href="https://www.mongodb.com/">MongoDB</a>.
  </p>
  <p>
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  </p>
  <pre><code class="language-bash">$ npm install apollo-server graphql mongoose</code></pre>
  <p>
    Next, create a new file called <code>index.js</code> and add the following code:
  </p>
  <pre><code class="language-javascript">// index.js
const { ApolloServer, PubSub } = require('apollo-server');
const mongoose = require('mongoose');
const typeDefs = require('./typeDefs');
const resolvers = require('./resolvers');

mongoose.connect('mongodb://localhost:27017/myapp', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true
}).then(() =&gt; {
  console.log('MongoDB connected');
}).catch((error) =&gt; {
  console.log(error);
});

const pubsub = new PubSub();

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req }) =&gt; ({ req, pubsub })
});

server.listen().then(({ url }) =&gt; {
  console.log(`Server listening on ${url}`);
});
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import the necessary dependencies: <code>ApolloServer</code>, <code>PubSub</code>, <code>mongoose</code>, and our own <code>typeDefs</code> and <code>resolvers</code>.
  </p>
  <p>
    Next, we connect to our MongoDB database using <code>mongoose.connect</code>. Make sure to replace <code>myapp</code> with your own database name.
  </p>
  <p>
    We then create a new instance of <code>PubSub</code>, which is used to publish and subscribe to messages.
  </p>
  <p>
    After that, we create a new instance of <code>ApolloServer</code> and pass in our <code>typeDefs</code>, <code>resolvers</code>, and a context object. The context object is where we can pass in any values that we want to make available to our resolvers. In this case, we're passing in <code>req</code> (the current request object) and <code>pubsub</code> (our instance of <code>PubSub</code>).
  </p>
  <p>
    Finally, we start the server and log the URL that it's running on. Our server is now ready to handle GraphQL queries and subscriptions!
  </p>
  <h2>Creating the GraphQL Schema</h2>
  <p>
    Now that we have our server set up, let's create our GraphQL schema. In this tutorial, we'll be building a simple chat application. We'll have a <code>Message</code> type that represents a message, and a <code>Query</code>, <code>Mutation</code>, and <code>Subscription</code> that allow us to retrieve, create, and subscribe to messages, respectively.
  </p>
  <p>
    Create a new folder called <code>schema</code>, and inside that folder, create a new file called <code>message.js</code>. Add the following code:
  </p>
  <pre><code class="language-javascript">// schema/message.js
const { gql } = require('apollo-server');

const typeDefs = gql`
  type Message {
    id: ID!
    text: String!
  }

  type Query {
    messages: [Message]!
  }

  type Mutation {
    addMessage(text: String!): Message!
  }

  type Subscription {
    newMessage: Message!
  }
`;

module.exports = typeDefs;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import <code>gql</code> from <code>apollo-server</code>.
  </p>
  <p>
    We then define a <code>Message</code> type with two fields: <code>id</code> (an ID) and <code>text</code> (a string).
  </p>
  <p>
    Next, we define a <code>Query</code> type with one field: <code>messages</code> (an array of <code>Message</code> objects).
  </p>
  <p>
    We then define a <code>Mutation</code> type with one field: <code>addMessage</code> (which takes a <code>text</code> argument and returns a <code>Message</code> object).
  </p>
  <p>
    Finally, we define a <code>Subscription</code> type with one field: <code>newMessage</code> (which returns a <code>Message</code> object).
  </p>
  <p>
    We export our schema using <code>module.exports</code>. That's it for our schema!
  </p>
  <h2>Creating the Resolvers</h2>
  <p>
    Next, let's create our resolvers. Resolvers are functions that handle GraphQL queries, mutations, and subscriptions.
  </p>
  <p>
    Create a new folder called <code>resolvers</code>, and inside that folder, create a new file called <code>message.js</code>. Add the following code:
  </p>
  <pre><code class="language-javascript">// resolvers/message.js
const Message = require('../models/Message');
const { PubSub } = require('apollo-server');

const pubsub = new PubSub();

const MESSAGE_ADDED = 'MESSAGE_ADDED';

const resolvers = {
  Query: {
    messages: async () =&gt; {
      const messages = await Message.find().sort({ createdAt: -1 });
      return messages;
    }
  },
  Mutation: {
    addMessage: async (_, { text }) =&gt; {
      const newMessage = new Message({
        text
      });
      const message = await newMessage.save();
      pubsub.publish(MESSAGE_ADDED, { newMessage: message });
      return message;
    }
  },
  Subscription: {
    newMessage: {
      subscribe: () =&gt; pubsub.asyncIterator([MESSAGE_ADDED])
    }
  }
};

module.exports = resolvers;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import our <code>Message</code> model and <code>PubSub</code> from <code>apollo-server</code>.
  </p>
  <p>
    We then create a new instance of <code>PubSub</code>. This is the same instance that we passed to our Apollo Server earlier.
  </p>
  <p>
    Next, we define a constant called <code>MESSAGE_ADDED</code> that we'll use as the topic for our subscription.
  </p>
  <p>
    We then define our resolvers. First, we have a <code>Query</code> resolver for <code>messages</code>, which returns an array of messages sorted by their <code>createdAt</code> date in descending order.
  </p>
  <p>
    Next, we have a <code>Mutation</code> resolver for <code>addMessage</code>, which takes a <code>text</code> argument and creates a new message in our MongoDB database. We then publish a message to our <code>MESSAGE_ADDED</code> topic using <code>pubsub.publish</code>, and return the newly created message.
  </p>
  <p>
    Finally, we have a <code>Subscription</code> resolver for <code>newMessage</code>, which uses <code>pubsub.asyncIterator</code> to subscribe to our <code>MESSAGE_ADDED</code> topic and return any new messages that are published. This resolver has to return an async iterator, which is what allows it to receive real-time updates.
  </p>
  <p>
    We export our resolvers using <code>module.exports</code>. That's it for our resolvers!
  </p>
  <h2>Connecting to the GraphQL API from a React Application</h2>
  <p>
    Now that our GraphQL API is set up, let's connect to it from our React application. In this tutorial, we'll be using the <a href="https://www.apollographql.com/docs/react/">Apollo Client</a> to do this.
  </p>
  <p>
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  </p>
  <pre><code class="language-bash">$ npm install apollo-boost @apollo/react-hooks subscriptions-transport-ws</code></pre>
  <p>
    <code>apollo-boost</code> is a package that provides a pre-configured Apollo Client, <code>@apollo/react-hooks</code> is a package that provides hooks to use with the Apollo Client, and <code>subscriptions-transport-ws</code> is a package that provides WebSocket support for subscriptions.
  </p>
  <p>
    Next, create a new file called <code>index.js</code> in your React app's <code>src</code> folder, and add the following code:
  </p>
  <pre><code class="language-javascript">// src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloProvider } from '@apollo/react-hooks';
import { ApolloClient } from 'apollo-client';
import { HttpLink } from 'apollo-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';
import App from './App';

const httpLink = new HttpLink({
  uri: 'http://localhost:4000/graphql'
});

const wsLink = new WebSocketLink({
  uri: 'ws://localhost:4000/graphql',
  options: {
    reconnect: true
  }
});

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

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

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import the necessary dependencies. We're using the WebSocketLink from <code>apollo-link-ws</code> to handle WebSocket subscriptions, and we're using the split function from <code>apollo-link</code> and the getMainDefinition function from <code>apollo-utilities</code> to split our link and send subscriptions over the WebSocketLink and everything else over the HttpLink.
  </p>
  <p>
    Next, we create a new instance of <code>HttpLink</code> with the URL of our GraphQL API.
  </p>
  <p>
    We then create a new instance of <code>WebSocketLink</code> with the WebSocket URL of our GraphQL API, and set the <code>reconnect</code> option to true so that the client automatically reconnects if it loses the WebSocket connection.
  </p>
  <p>
    Next, we create a new link using <code>split</code> that decides whether to use the WebSocketLink or HttpLink based on the type of operation being performed. If it's a subscription, we use the WebSocketLink; if it's anything else, we use the HttpLink.
  </p>
  <p>
    Finally, we create a new instance of <code>ApolloClient</code> with our link and an <code>InMemoryCache</code>, and wrap our <code>App</code> component in an <code>ApolloProvider</code> that passes the client down to all child components.
  </p>
  <p>
    Our React application is now connected to our GraphQL API using the Apollo Client!
  </p>
  <h2>Using GraphQL Subscriptions in React</h2>
  <p>
    Now that we have our React app connected to our GraphQL API, let's use GraphQL subscriptions to receive real-time updates whenever a new message is added.
  </p>
  <p>
    Create a new file called <code>Chat.js</code> in your React app's <code>src</code> folder, and add the following code:
  </p>
  <pre><code class="language-javascript">// src/Chat.js
import React, { useState } from 'react';
import { useSubscription, useMutation } from '@apollo/react-hooks';
import { gql } from 'apollo-boost';

const MESSAGES_QUERY = gql`
  {
    messages {
      id
      text
    }
  }
`;

const MESSAGE_ADDED_SUBSCRIPTION = gql`
  subscription {
    newMessage {
      id
      text
    }
  }
`;

const ADD_MESSAGE_MUTATION = gql`
  mutation AddMessage($text: String!) {
    addMessage(text: $text) {
      id
      text
    }
  }
`;

function Chat() {
  const [text, setText] = useState('');
  const [addMessage] = useMutation(ADD_MESSAGE_MUTATION);

  const sendChatMessage = () =&gt; {
    addMessage({
      variables: {
        text: text
      },
      optimisticResponse: {
        addMessage: {
          __typename: 'Message',
          id: -1,
          text: text
        }
      },
      update: (proxy, { data: { addMessage } }) =&gt; {
        const data = proxy.readQuery({ query: MESSAGES_QUERY });
        data.messages.unshift(addMessage);
        proxy.writeQuery({ query: MESSAGES_QUERY, data });
      }
    });

    setText('');
  };

  const { loading, error, data } = useSubscription(
    MESSAGE_ADDED_SUBSCRIPTION
  );

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error: {error.message}&lt;/p&gt;;

  return (
    &lt;div&gt;
      &lt;ul&gt;
        {data.messages.map(message =&gt; (
          &lt;li key={message.id}&gt;{message.text}&lt;/li&gt;
        ))}
      &lt;/ul&gt;
      &lt;div&gt;
        &lt;input type="text" value={text} onChange={e =&gt; setText(e.target.value)} /&gt;
        &lt;button onClick={sendChatMessage}&gt;Send&lt;/button&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  );
}

export default Chat;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we define our <code>MESSAGES_QUERY</code>, which retrieves an array of messages, and our <code>MESSAGE_ADDED_SUBSCRIPTION</code>, which subscribes to new messages.
  </p>
  <p>
    We then define our <code>ADD_MESSAGE_MUTATION</code>, which takes a <code>text</code> argument and creates a new message in our MongoDB database. We're also using <code>optimisticResponse</code> to optimistically update the UI before the server responds, and <code>update</code> to update the cache with the newly created message.
  </p>
  <p>
    We then define our <

Learn how to create real-time web applications using GraphQL subscriptions in combination with React for a seamless user experience. Explore how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app.

Building Real-Time Applications with GraphQL Subscriptions and React


  Efficient API Handling: GraphQL and Apollo for Modern React Applications
  
  If you’re a web developer, you've probably heard of GraphQL and Apollo. These two technologies have revolutionized the way we interact with APIs. Instead of using traditional REST APIs, GraphQL and Apollo provide a more efficient way to handle data and offer many benefits such as, reducing the amount of unnecessary data transferred over the network, more advanced caching capabilities, and ease of use, especially in larger projects with lots of data to handle. 
  
  In this tutorial, we’ll go over the basics of GraphQL and Apollo and demonstrate how they can be integrated into modern React applications, to provide a more streamlined and efficient handling of APIs.
  
  What is GraphQL?
  
  GraphQL is a query language designed specifically for APIs. It was created by Facebook in 2012 and released to the public in 2015, and has since then become a popular alternative to traditional REST APIs. What makes GraphQL stand out is the ability to request only the exact data you need, rather than requesting entire resources from the backend.
  
  Key Features of GraphQL
  
  Some of the key features of GraphQL include:
  
  
    A single endpoint for all data requests
    Efficient and precise data fetching
    Strong typing and sophisticated schema validation
    Easy integration with front-end frameworks and libraries
    Powerful tooling, such as GraphiQL and GraphQL Playground
  
  
  What is Apollo?
  
  Apollo is a set of tools and libraries for GraphQL, created by the team at ApolloGraphQL. The Apollo Client is a powerful state management library, designed specifically for React applications, that integrates with GraphQL APIs. It provides a seamless way for clients to interact with the server and dispatch data updates across components.
  
  Key Features of Apollo
  
  Some of the key features of Apollo include:
  
  
    Easy integration with React applications
    Efficient data fetching and caching
    Flexible error handling and query management
    Powerful debugging and development tooling
    Compatibility across various servers, clients, and stacks
  
  
  How To Get Started
  
  Let’s now dive into the code and see how to integrate GraphQL and Apollo in a React application. For this tutorial, we'll be creating a simple application that fetches a list of books from a GraphQL server using Apollo.
  
  Setting Up a GraphQL Server with Node.js and Express.js
  
  As this tutorial focuses on how to integrate Apollo with a React application, setting up a GraphQL server is out of the scope. However, you can follow the instructions in this article to build an example GraphQL server with Node.js and Express.js, along with a Postgres database: Building a GraphQL API with Apollo Server in Node.js.
  
  Setting Up Apollo Client in React

  First, let's create a new React application using create-react-app:

  npx create-react-app my-apollo-app
cd my-apollo-app


  Next, let's install the necessary dependencies:

  npm install apollo-boost react-apollo graphql graphql-tag


  Now that we have all the dependencies, let’s create a new file, and name it index.js, inside the src directory:

  import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

import ApolloClient from 'apollo-boost';
import { ApolloProvider } from 'react-apollo';

const client = new ApolloClient({
  uri: 'http://localhost:4000/graphql'
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;
  , document.getElementById('root')
);


  As you can see, we've initialized a new ApolloClient and passed in the GraphQL server’s URL to the uri property. We've also wrapped our component App with the ApolloProvider component, which gives the app access to the ApolloClient instance. The client instance is then passed as a prop to the provider component.

  Fetching Data with Apollo

  Now that we've set up the Apollo Client, let’s create a new component and fetch some data from the server. Create a new file Books.js inside the src/components/ directory, and add the following code:

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

const GET_BOOKS = gql`
  {
    books {
      title,
      author
    }
  }
`;

const Books = () => (
  &lt;Query query={GET_BOOKS}&gt;
    {({ data, loading, error }) =&gt; {
      if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
      if (error) return &lt;p&gt;Error :(&lt;/p&gt;;

      return data.books.map(({ title, author }) => (
        &lt;div key={title}&gt;
          &lt;h4&gt;{title} - {author}&lt;/h4&gt;
        &lt;/div&gt;
      ));
    }}
  &lt;/Query&gt;
);

export default Books;


  Here, we’ve defined a new query, GET_BOOKS, to fetch the data for books. We’re also using the Query component that comes with the react-apollo library that wraps our query and retrieves data from the server. The component is passed a query prop that specifies the query we defined earlier.

  The child function of the Query component, which receives the server data (data), as well as loading state and error objects, will be called with the most recent results every time data is updated by the server. The function then handles and modifies the data before rendering it as HTML elements. The function first checks if data is loading, and if so, it renders a loading indicator. If an error occurs, we render an error message to the user, indicating that something went wrong. Finally, if the server returns data, the function maps over the books array and renders the book's title and author as an HTML element.

  Now, let’s add the Books component to our App component. Open the App.js file in the src directory:

  import React, { Component } from 'react';
import Books from './components/Books';

class App extends Component {
  render() {
    return (
      &lt;div className="App"&gt;
        &lt;h1&gt;List of Books&lt;/h1&gt;&lt;hr /&gt;
        &lt;Books /&gt;
      &lt;/div&gt;
    );
  }
}

export default App;


  Here, we’ve imported our Books component and rendered it inside our App component. The component renders a header followed by the Books component.

  Conclusion

  In conclusion, GraphQL and Apollo offer powerful and performant solutions for managing API calls in modern web development. Apollo provides an easy way to integrate with React applications and can be used with other libraries such as Redux to manage application state. While GraphQL may seem like a new concept, it’s quickly becoming the foundation of modern API development, especially with high-bandwidth applications. Using GraphQL with Apollo Client allows you to streamline data interactions, reducing the amount of unnecessary data transmitted while ensuring that your application stays performant.

  So, go ahead and explore the powerful world of GraphQL and Apollo and discover what’s possible in modern development.


<div>
  <h1>Efficient API Handling: GraphQL and Apollo for Modern React Applications</h1>
  
  <p>If you’re a web developer, you've probably heard of GraphQL and Apollo. These two technologies have revolutionized the way we interact with APIs. Instead of using traditional REST APIs, GraphQL and Apollo provide a more efficient way to handle data and offer many benefits such as, reducing the amount of unnecessary data transferred over the network, more advanced caching capabilities, and ease of use, especially in larger projects with lots of data to handle. </p>
  
  <p>In this tutorial, we’ll go over the basics of GraphQL and Apollo and demonstrate how they can be integrated into modern React applications, to provide a more streamlined and efficient handling of APIs.</p>
  
  <h2>What is GraphQL?</h2>
  
  <p>GraphQL is a query language designed specifically for APIs. It was created by Facebook in 2012 and released to the public in 2015, and has since then become a popular alternative to traditional REST APIs. What makes GraphQL stand out is the ability to request only the exact data you need, rather than requesting entire resources from the backend.</p>
  
  <h2>Key Features of GraphQL</h2>
  
  <p>Some of the key features of GraphQL include:</p>
  
  <ul>
    <li>A single endpoint for all data requests</li>
    <li>Efficient and precise data fetching</li>
    <li>Strong typing and sophisticated schema validation</li>
    <li>Easy integration with front-end frameworks and libraries</li>
    <li>Powerful tooling, such as GraphiQL and GraphQL Playground</li>
  </ul>
  
  <h2>What is Apollo?</h2>
  
  <p>Apollo is a set of tools and libraries for GraphQL, created by the team at ApolloGraphQL. The Apollo Client is a powerful state management library, designed specifically for React applications, that integrates with GraphQL APIs. It provides a seamless way for clients to interact with the server and dispatch data updates across components.</p>
  
  <h2>Key Features of Apollo</h2>
  
  <p>Some of the key features of Apollo include:</p>
  
  <ul>
    <li>Easy integration with React applications</li>
    <li>Efficient data fetching and caching</li>
    <li>Flexible error handling and query management</li>
    <li>Powerful debugging and development tooling</li>
    <li>Compatibility across various servers, clients, and stacks</li>
  </ul>
  
  <h2>How To Get Started</h2>
  
  <p>Let’s now dive into the code and see how to integrate GraphQL and Apollo in a React application. For this tutorial, we'll be creating a simple application that fetches a list of books from a GraphQL server using Apollo.</p>
  
  <h3>Setting Up a GraphQL Server with Node.js and Express.js</h3>
  
  <p>As this tutorial focuses on how to integrate Apollo with a React application, setting up a GraphQL server is out of the scope. However, you can follow the instructions in this article to build an example GraphQL server with Node.js and Express.js, along with a Postgres database: <a href="https://www.robinwieruch.de/graphql-apollo-server-tutorial/">Building a GraphQL API with Apollo Server in Node.js</a>.</p>
  
  <h3>Setting Up Apollo Client in React</h3>

  <p>First, let's create a new React application using create-react-app:</p>

  <pre><code>npx create-react-app my-apollo-app
cd my-apollo-app
</code></pre>

  <p>Next, let's install the necessary dependencies:</p>

  <pre><code>npm install apollo-boost react-apollo graphql graphql-tag
</code></pre>

  <p>Now that we have all the dependencies, let’s create a new file, and name it <code>index.js</code>, inside the <code>src</code> directory:</p>

  <pre><code>import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

import ApolloClient from 'apollo-boost';
import { ApolloProvider } from 'react-apollo';

const client = new ApolloClient({
  uri: 'http://localhost:4000/graphql'
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;
  , document.getElementById('root')
);
</code></pre>

  <p>As you can see, we've initialized a new <code>ApolloClient</code> and passed in the GraphQL server’s URL to the <code>uri</code> property. We've also wrapped our component <code>App</code> with the <code>ApolloProvider</code> component, which gives the app access to the <code>ApolloClient</code> instance. The client instance is then passed as a prop to the provider component.</p>

  <h3>Fetching Data with Apollo</h3>

  <p>Now that we've set up the Apollo Client, let’s create a new component and fetch some data from the server. Create a new file <code>Books.js</code> inside the <code>src/components/</code> directory, and add the following code:</p>

  <pre><code>import React from 'react';
import { Query } from 'react-apollo';
import gql from 'graphql-tag';

const GET_BOOKS = gql`
  {
    books {
      title,
      author
    }
  }
`;

const Books = () => (
  &lt;Query query={GET_BOOKS}&gt;
    {({ data, loading, error }) =&gt; {
      if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
      if (error) return &lt;p&gt;Error :(&lt;/p&gt;;

      return data.books.map(({ title, author }) => (
        &lt;div key={title}&gt;
          &lt;h4&gt;{title} - {author}&lt;/h4&gt;
        &lt;/div&gt;
      ));
    }}
  &lt;/Query&gt;
);

export default Books;
</code></pre>

  <p>Here, we’ve defined a new query, <code>GET_BOOKS</code>, to fetch the data for books. We’re also using the <code>Query</code> component that comes with the <code>react-apollo</code> library that wraps our query and retrieves data from the server. The component is passed a <code>query</code> prop that specifies the query we defined earlier.</p>

  <p>The child function of the Query component, which receives the server data (<code>data</code>), as well as loading state and error objects, will be called with the most recent results every time data is updated by the server. The function then handles and modifies the data before rendering it as HTML elements. The function first checks if data is loading, and if so, it renders a loading indicator. If an error occurs, we render an error message to the user, indicating that something went wrong. Finally, if the server returns data, the function maps over the books array and renders the book's title and author as an HTML element.</p>

  <p>Now, let’s add the <code>Books</code> component to our <code>App</code> component. Open the <code>App.js</code> file in the src directory:</p>

  <pre><code>import React, { Component } from 'react';
import Books from './components/Books';

class App extends Component {
  render() {
    return (
      &lt;div className="App"&gt;
        &lt;h1&gt;List of Books&lt;/h1&gt;&lt;hr /&gt;
        &lt;Books /&gt;
      &lt;/div&gt;
    );
  }
}

export default App;
</code></pre>

  <p>Here, we’ve imported our <code>Books</code> component and rendered it inside our <code>App</code> component. The component renders a header followed by the Books component.</p>

  <h2>Conclusion</h2>

  <p>In conclusion, GraphQL and Apollo offer powerful and performant solutions for managing API calls in modern web development. Apollo provides an easy way to integrate with React applications and can be used with other libraries such as Redux to manage application state. While GraphQL may seem like a new concept, it’s quickly becoming the foundation of modern API development, especially with high-bandwidth applications. Using GraphQL with Apollo Client allows you to streamline data interactions, reducing the amount of unnecessary data transmitted while ensuring that your application stays performant.</p>

  <p>So, go ahead and explore the powerful world of GraphQL and Apollo and discover what’s possible in modern development.</p>
</div>

Discover how to streamline your API interactions and improve performance by integrating GraphQL and Apollo in your React applications. In this tutorial, learn the benefits of GraphQL over REST, set up Apollo Client within your React app, and interact effortlessly with your backend.

Efficient API Handling: GraphQL and Apollo for Modern React Applications


  Demystifying GraphQL: Accelerate Your Data-Driven Full Stack Applications
  
    With the rapid evolution of web development technologies, building robust, scalable, and efficient APIs has become crucial. GraphQL is a query language and runtime designed to make it incredibly easy to request exactly what data you need in your applications. In this article, we'll cover the basics of GraphQL, the differences with REST, and how to utilize it with popular frameworks like React and Apollo.
  

  What is GraphQL?
  
    GraphQL, initially developed by Facebook in 2012, is both a query language and runtime for APIs. It provides a more flexible and efficient approach to working with data, empowering developers to request the exact data they need and nothing more. This helps reduce bandwidth usage and speeds up application performance, while also making it simpler for front-end developers to work with complex data schemas.
  
  
    Unlike REST, which is based on a fixed set of endpoints and HTTP methods, GraphQL allows you to create a single endpoint that can handle a variety of data operations. This enables clients to shape their requests as needed, and receive responses that contain only the relevant data. This eliminates over-fetching and under-fetching, which can be problematic in REST API architectures.
  

  Understanding GraphQL vs REST
  
    Before diving deeper into creating a GraphQL API, it's essential to understand the core differences between GraphQL and REST. Let's take a closer look at some key distinctions:
  

  Single Endpoint vs Multiple Endpoints
  
    One of the most notable differences between REST and GraphQL is how they handle endpoints. A REST API consists of multiple endpoints, each performing a specific operation on a specific resource (e.g., GET /users, POST /users). On the other hand, GraphQL has a single endpoint that accepts different types of queries or mutations (actions to modify data) to interact with the underlying data store.
  

  Flexible Queries vs Fixed Operations
  
    With REST, responses from endpoints are predefined and static, which can lead to over-fetching or under-fetching of data. GraphQL resolves this issue by enabling clients to request only the necessary data fields they need. This flexibility allows for more efficient data fetching and reduces the amount of unnecessary data sent over the wire.
  

  Type System vs No Type System
  
    GraphQL APIs are strongly typed, meaning that their schema defines the exact shape and types of data a client can request. This makes it easier for clients to understand and use the API, and provides a foundation for powerful tools for validation and auto-generating code based on the schema. REST APIs, however, do not include type systems out of the box, although some conventions encourage a more structured approach.
  

  Getting Started with GraphQL in a React Application
  
    Now that we understand the benefits of GraphQL, let's dive into using it with React and Apollo, a popular library for integrating GraphQL into your applications. Here's a quick setup for a React application that utilizes the Apollo-Client to interact with a GraphQL API.
  
  
    First, install the necessary dependencies for Apollo Client and set up the client:
  
  npm install @apollo/client graphql
  
  
    Then, configure the Apollo Client in your application:
  
  &lt;!-- src/index.js --&gt;
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloClient, InMemoryCache, ApolloProvider } from '@apollo/client';
import App from './App';

const client = new ApolloClient({
  uri: 'https://your-graphql-api-url.com/graphql',
  cache: new InMemoryCache(),
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  
  
    To fetch data, you can use the 'useQuery' hook provided by Apollo Client like so:
  
  &lt;!-- src/App.js --&gt;
import React from 'react';
import { useQuery, gql } from '@apollo/client';

const GET_USERS = gql`
  query {
    users {
      id
      name
      email
    }
  }
`;

function App() {
  const { loading, error, data } = useQuery(GET_USERS);

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error :( &lt;/p&gt;;

  return (
    &lt;div&gt;
      {data.users.map((user) =&gt; (
        &lt;p key={user.id}&gt;{user.name}&lt;/p&gt;
      ))}
    &lt;/div&gt;
  );
}

export default App;
  
  
    In this example, we fetch a list of users and display their names on the page. We define a GraphQL query using the gql template literal, and then utilize the 'useQuery' hook to fetch data from our API. The hook returns an object containing 'loading', 'error', and 'data' properties, which we can use to manage the different states of our component.
  

  Conclusion
  
    GraphQL provides a powerful and flexible way to work with data-driven applications, offering a modern alternative to traditional REST APIs. By using GraphQL in conjunction with React and Apollo, you can build incredibly scalable and efficient applications that optimize bandwidth use and simplify development workflows. To learn more about using GraphQL, visit their official website.
  


<div>
  <h1>Demystifying GraphQL: Accelerate Your Data-Driven Full Stack Applications</h1>
  <p>
    With the rapid evolution of web development technologies, building robust, scalable, and efficient APIs has become crucial. GraphQL is a query language and runtime designed to make it incredibly easy to request exactly what data you need in your applications. In this article, we'll cover the basics of GraphQL, the differences with REST, and how to utilize it with popular frameworks like React and Apollo.
  </p>

  <h2>What is GraphQL?</h2>
  <p>
    GraphQL, initially developed by Facebook in 2012, is both a query language and runtime for APIs. It provides a more flexible and efficient approach to working with data, empowering developers to request the exact data they need and nothing more. This helps reduce bandwidth usage and speeds up application performance, while also making it simpler for front-end developers to work with complex data schemas.
  </p>
  <p>
    Unlike REST, which is based on a fixed set of endpoints and HTTP methods, GraphQL allows you to create a single endpoint that can handle a variety of data operations. This enables clients to shape their requests as needed, and receive responses that contain only the relevant data. This eliminates over-fetching and under-fetching, which can be problematic in REST API architectures.
  </p>

  <h2>Understanding GraphQL vs REST</h2>
  <p>
    Before diving deeper into creating a GraphQL API, it's essential to understand the core differences between GraphQL and REST. Let's take a closer look at some key distinctions:
  </p>

  <h3>Single Endpoint vs Multiple Endpoints</h3>
  <p>
    One of the most notable differences between REST and GraphQL is how they handle endpoints. A REST API consists of multiple endpoints, each performing a specific operation on a specific resource (e.g., GET /users, POST /users). On the other hand, GraphQL has a single endpoint that accepts different types of queries or mutations (actions to modify data) to interact with the underlying data store.
  </p>

  <h3>Flexible Queries vs Fixed Operations</h3>
  <p>
    With REST, responses from endpoints are predefined and static, which can lead to over-fetching or under-fetching of data. GraphQL resolves this issue by enabling clients to request only the necessary data fields they need. This flexibility allows for more efficient data fetching and reduces the amount of unnecessary data sent over the wire.
  </p>

  <h3>Type System vs No Type System</h3>
  <p>
    GraphQL APIs are strongly typed, meaning that their schema defines the exact shape and types of data a client can request. This makes it easier for clients to understand and use the API, and provides a foundation for powerful tools for validation and auto-generating code based on the schema. REST APIs, however, do not include type systems out of the box, although some conventions encourage a more structured approach.
  </p>

  <h2>Getting Started with GraphQL in a React Application</h2>
  <p>
    Now that we understand the benefits of GraphQL, let's dive into using it with React and Apollo, a popular library for integrating GraphQL into your applications. Here's a quick setup for a React application that utilizes the Apollo-Client to interact with a GraphQL API.
  </p>
  <p>
    First, install the necessary dependencies for Apollo Client and set up the client:
  </p>
  <pre><code class="language-html">npm install @apollo/client graphql
  </code></pre>
  <p>
    Then, configure the Apollo Client in your application:
  </p>
  <pre><code class="language-html">&lt;!-- src/index.js --&gt;
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloClient, InMemoryCache, ApolloProvider } from '@apollo/client';
import App from './App';

const client = new ApolloClient({
  uri: 'https://your-graphql-api-url.com/graphql',
  cache: new InMemoryCache(),
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  </code></pre>
  <p>
    To fetch data, you can use the 'useQuery' hook provided by Apollo Client like so:
  </p>
  <pre><code class="language-html">&lt;!-- src/App.js --&gt;
import React from 'react';
import { useQuery, gql } from '@apollo/client';

const GET_USERS = gql`
  query {
    users {
      id
      name
      email
    }
  }
`;

function App() {
  const { loading, error, data } = useQuery(GET_USERS);

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error :( &lt;/p&gt;;

  return (
    &lt;div&gt;
      {data.users.map((user) =&gt; (
        &lt;p key={user.id}&gt;{user.name}&lt;/p&gt;
      ))}
    &lt;/div&gt;
  );
}

export default App;
  </code></pre>
  <p>
    In this example, we fetch a list of users and display their names on the page. We define a GraphQL query using the gql template literal, and then utilize the 'useQuery' hook to fetch data from our API. The hook returns an object containing 'loading', 'error', and 'data' properties, which we can use to manage the different states of our component.
  </p>

  <h2>Conclusion</h2>
  <p>
    GraphQL provides a powerful and flexible way to work with data-driven applications, offering a modern alternative to traditional REST APIs. By using GraphQL in conjunction with React and Apollo, you can build incredibly scalable and efficient applications that optimize bandwidth use and simplify development workflows. To learn more about using GraphQL, visit their <a href="https://graphql.org/">official website</a>.
  </p>
</div>

Explore how GraphQL can streamline your data-fetching process in modern full stack applications, enabling you to easily design scalable and performance-efficient API architecture. We'll cover the basics of GraphQL, the differences with REST, and how to utilize it with popular frameworks like React and Apollo.