Introduction to GraphQL Clients

When it comes to integrating GraphQL into your React application, two of the most popular and widely-used clients are Apollo Client and Relay. Both libraries have their strengths and weaknesses, and choosing the right one depends on your specific needs and the structure of your application.

Structure vs Flexibility

One of the most significant differences between Apollo and Relay is their approach to structure and flexibility.

  • Relay: Relay is highly opinionated and structured. It requires a specific schema and enforces strict rules on how queries are structured. This rigidity can be beneficial for large teams with varying skill levels, as it ensures consistency across the application. However, it can be challenging to set up and may feel restrictive for smaller projects or those requiring more flexibility.

  • Apollo: Apollo, on the other hand, is flexible and easygoing. It allows developers to integrate GraphQL in various ways, making it easier to introduce into existing applications. Apollo does not impose a specific schema and provides more freedom in how queries are handled. This flexibility, however, may require more manual work to ensure data consistency.

Setup and Complexity

  • Relay: Setting up Relay involves more steps and requires a custom schema that matches your backend schema. Relay also uses a compiler that must be run during development to ensure compliance with its strict rules. This can be time-consuming and may introduce additional complexity, especially for smaller applications.

  • Apollo: Apollo is much easier to set up. It involves installing a single package and adding the ApolloProvider to the root of your React tree. This simplicity makes Apollo a more accessible choice for developers new to GraphQL.

Documentation and Community Support

  • Relay: Relay’s documentation is often criticized for being opaque and incomplete. Finding support and resources for Relay can be challenging, partly because it was initially developed as an internal Facebook tool and still retains some of that complexity.

  • Apollo: Apollo’s documentation is more thorough and beginner-friendly. The community support for Apollo is also more robust, with easier access to resources and answers on platforms like StackOverflow.

Queries, Mutations, and Subscriptions

  • Relay: Relay handles queries and mutations through its strict schema requirements. It does not natively support subscriptions, although community efforts have made some progress in this area.

  • Apollo: Apollo supports queries, mutations, and subscriptions out of the box. It integrates well with subscriptions-transport-ws, making real-time data updates straightforward.

Example Usage

Here is a simple example of how you might use Apollo Client to fetch data:

import React from 'react';
import { ApolloClient, InMemoryCache, ApolloProvider, useQuery, gql } from '@apollo/client';

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

const GET_RATES = gql`
  query GetRates {
    rates(currency: "USD") {
      currency
      rate
    }
  }
`;

function ExchangeRates() {
  const { loading, error, data } = useQuery(GET_RATES);

  if (loading) return <p>Loading...</p>;
  if (error) return <p>Error :(</p>;

  return data.rates.map(({ currency, rate }) => (
    <div key={currency}>
      <p>{`${currency}: ${rate}`}</p>
    </div>
  ));
}

function App() {
  return (
    <ApolloProvider client={client}>
      <ExchangeRates />
    </ApolloProvider>
  );
}

Conclusion

Choosing between Apollo and Relay depends on your project’s specific needs:

  • Use Relay if you are building a large-scale application with complex data requirements and numerous dependencies. Relay’s structured approach can help maintain consistency and efficiency, despite the higher entry barrier.

  • Use Apollo if you need flexibility and ease of integration. Apollo is ideal for projects where you want to quickly get started with GraphQL or need to introduce it into an existing application. Its flexibility and robust community support make it a popular choice for many developers.

Ultimately, the choice between Apollo and Relay should be based on your team’s experience, the complexity of your application, and the level of structure and flexibility you require.