Introduction

GraphQL has revolutionized how we fetch and manage data in modern applications, offering a flexible and efficient alternative to REST APIs. When combined with Apollo Client in a React application, it provides a powerful solution for state management and data fetching. With React 18's introduction of Suspense and Concurrent Features, we can now take this combination to the next level—delivering smoother user experiences with optimized rendering and loading states.

In this post, we'll explore how to integrate GraphQL with Apollo Client while leveraging React Suspense and Concurrent Features to build performant, user-friendly applications. We'll cover key concepts, practical implementations, and best practices to help you get the most out of these technologies.

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## Setting Up Apollo Client with React Suspense

React Suspense allows components to "wait" for asynchronous operations (like data fetching) before rendering. When paired with Apollo Client, we can use Suspense to streamline data loading in our applications.

### Installing Dependencies

First, ensure you have the necessary packages installed:

npm install @apollo/client graphql react react-dom

### Configuring Apollo Client

To enable Suspense with Apollo Client, we need to configure it with the SuspenseCache:

import { ApolloClient, InMemoryCache, SuspenseCache } from '@apollo/client';  

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

const suspenseCache = new SuspenseCache();  

export { client, suspenseCache };

### Using Suspense with Apollo Queries

Now, we can use the useSuspenseQuery hook (introduced in Apollo Client v3.8+) to fetch data with Suspense:

import { useSuspenseQuery } from '@apollo/client';  
import { Suspense } from 'react';  

const GET_DATA = gql`  
  query GetData {  
    posts {  
      id  
      title  
    }  
  }  
`;  

function DataComponent() {  
  const { data } = useSuspenseQuery(GET_DATA);  

  return (  
    <ul>  
      {data.posts.map((post) => (  
        <li key={post.id}>{post.title}</li>  
      ))}  
    </ul>  
  );  
}  

function App() {  
  return (  
    <Suspense fallback={<div>Loading...</div>}>  
      <DataComponent />  
    </Suspense>  
  );  
}

Here, the fallback prop in Suspense ensures a loading state is shown while the query resolves.

---

## Leveraging Concurrent Features with Apollo

React 18's Concurrent Features allow applications to remain responsive during rendering by prioritizing updates. When combined with Apollo Client, we can optimize how data is fetched and rendered.

### Using useTransition for Non-Blocking Updates

The useTransition hook lets us mark certain state updates as non-urgent, improving perceived performance. Here’s how we can use it with Apollo:

import { useTransition } from 'react';  
import { useQuery } from '@apollo/client';  

function PostList() {  
  const [isPending, startTransition] = useTransition();  
  const { data, refetch } = useQuery(GET_DATA);  

  const handleRefresh = () => {  
    startTransition(() => {  
      refetch();  
    });  
  };  

  return (  
    <div>  
      <button onClick={handleRefresh} disabled={isPending}>  
        {isPending ? 'Refreshing...' : 'Refresh Data'}  
      </button>  
      <ul>  
        {data?.posts.map((post) => (  
          <li key={post.id}>{post.title}</li>  
        ))}  
      </ul>  
    </div>  
  );  
}

In this example, startTransition ensures the UI remains responsive while data is being refetched.

### Combining Suspense and useDeferredValue

useDeferredValue helps defer less critical updates, improving performance for slow renders. Here’s how it works with Apollo:

import { useDeferredValue } from 'react';  

function SearchResults({ searchTerm }) {  
  const deferredSearchTerm = useDeferredValue(searchTerm);  
  const { data } = useSuspenseQuery(SEARCH_QUERY, {  
    variables: { term: deferredSearchTerm },  
  });  

  return (  
    <div>  
      {data.searchResults.map((result) => (  
        <div key={result.id}>{result.name}</div>  
      ))}  
    </div>  
  );  
}

This ensures the UI remains smooth even when handling large datasets or slow network responses.

---

## Error Handling and Optimistic Updates

### Error Boundaries with Suspense

Since Suspense doesn’t handle errors by default, we need to wrap our components in an Error Boundary:

class ErrorBoundary extends React.Component {  
  state = { hasError: false };  

  static getDerivedStateFromError() {  
    return { hasError: true };  
  }  

  render() {  
    if (this.state.hasError) {  
      return <div>Something went wrong!</div>;  
    }  
    return this.props.children;  
  }  
}  

function App() {  
  return (  
    <ErrorBoundary>  
      <Suspense fallback={<div>Loading...</div>}>  
        <DataComponent />  
      </Suspense>  
    </ErrorBoundary>  
  );  
}

### Optimistic UI with Apollo

Apollo Client supports optimistic updates to make the UI feel faster. Here’s an example with mutations:

const ADD_POST = gql`  
  mutation AddPost($title: String!) {  
    addPost(title: $title) {  
      id  
      title  
    }  
  }  
`;  

function AddPostForm() {  
  const [addPost] = useMutation(ADD_POST, {  
    optimisticResponse: {  
      addPost: {  
        id: 'temp-id',  
        title: 'Optimistic Post',  
        __typename: 'Post',  
      },  
    },  
    update(cache, { data: { addPost } }) {  
      cache.modify({  
        fields: {  
          posts(existingPosts = []) {  
            return [...existingPosts, addPost];  
          },  
        },  
      });  
    },  
  });  

  const handleSubmit = (e) => {  
    e.preventDefault();  
    addPost({ variables: { title: 'New Post' } });  
  };  

  return <form onSubmit={handleSubmit}>{/* Form fields */}</form>;  
}

This ensures the UI updates immediately while the mutation resolves in the background.

---

Conclusion

Combining GraphQL, Apollo Client, and React Suspense/Concurrent Features unlocks a new level of performance and user experience in modern applications. By leveraging Suspense for seamless loading states, useTransition for non-blocking updates, and optimistic UI techniques, we can build applications that feel faster and more responsive.

As React continues to evolve, these patterns will become even more critical for high-performance applications. Start integrating them today to stay ahead of the curve!

Would you like a deeper dive into any specific aspect? Let us know in the comments! 🚀