Using GraphQL with React Native: Best Practices and Examples

React Native is a popular framework for developing mobile applications. It allows developers to create apps that run on both iOS and Android platforms with a single codebase. GraphQL is a query language for APIs that allows for efficient, flexible, and powerful data retrieval. Combining React Native with GraphQL can help developers create high-performing and scalable mobile applications. In this article, we will discuss best practices for using GraphQL with React Native and provide examples to help you get started.

What is GraphQL?

GraphQL is a query language for APIs that was developed by Facebook. It allows developers to specify the data they need, and the server will return only that data, rather than sending back a pre-defined set of data. This results in faster and more efficient communication between the client and server, as well as more flexible and powerful data retrieval.

GraphQL has a strong type system, which helps to ensure that the data returned is in the expected format. It also allows for real-time updates through subscriptions, making it a great choice for applications that require real-time data.

Setting up a GraphQL server

Before we can start using GraphQL with React Native, we need to set up a GraphQL server. There are many options for setting up a GraphQL server, including Apollo Server, Prisma, and Hasura.

In this article, we will use Apollo Server, which is a popular and easy-to-use option. To get started, we will create a new project using the following command:

npm init

Next, we will install the necessary packages:

npm install apollo-server graphql

We can now create a new file, index.js, and add the following code:

const { ApolloServer, gql } = require('apollo-server');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({ typeDefs, resolvers });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

This code sets up a simple GraphQL server with a single hello query that returns the string "Hello world!". To start the server, we can run the following command:

node index.js

If everything is set up correctly, we should see the following message in the console:

🚀 Server ready at http://localhost:4000/

Using GraphQL with React Native

Now that we have set up a GraphQL server, we can start using GraphQL with React Native. We will use the Apollo Client library to connect to our GraphQL server.

To get started, we will create a new React Native project using the following command:

npx react-native init MyProject

Next, we will install the necessary packages:

npm install @apollo/client graphql

We can now create a new file, App.js, and add the following code:

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

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

const GET_HELLO = gql`
  query {
    hello
  }
`;

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

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

  return (
    <View style={{ flex: 1 }}>
      <Text>{data.hello}</Text>
    </View>
  );
}

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

This code sets up a basic React Native app that connects to our GraphQL server and queries the hello query we defined earlier. We use the useQuery hook from the @apollo/client package to fetch the data and display it in a Text component.

Best practices for using GraphQL with React Native

1. Use Apollo Client for state management

Apollo Client is a powerful tool for state management in React Native applications. It provides a simple and efficient way to manage data, as well as tools for caching and optimistic updates.

Using Apollo Client allows us to write less code and avoid unnecessary re-renders. It also makes it easy to share data between components and manage complex data dependencies.

2. Use Fragments to improve performance

GraphQL Fragments allow us to define reusable pieces of queries that can be included in other queries. This can help to improve performance by reducing the amount of data that needs to be transferred over the network.

For example, we can define a fragment for a user that includes their name and email:

const USER_FRAGMENT = gql`
  fragment UserFragment on User {
    name
    email
  }
`;

We can then use this fragment in other queries:

const GET_USER = gql`
  query getUser($id: ID!) {
    user(id: $id) {
      ...UserFragment
    }
  }
  ${USER_FRAGMENT}
`;

3. Use Subscriptions for real-time updates

GraphQL Subscriptions allow us to subscribe to changes in data and receive real-time updates. This can be useful for applications that require real-time data, such as chat applications or real-time dashboards.

To use subscriptions in React Native, we can use the useSubscription hook from the @apollo/client package. We can define a subscription like this:

const MESSAGE_SUBSCRIPTION = gql`
  subscription {
    newMessage {
      id
      text
      createdAt
      author {
        name
      }
    }
  }
`;

function MessageList() {
  const { data } = useSubscription(MESSAGE_SUBSCRIPTION);

  if (!data) {
    return null;
  }

  return (
    <FlatList
      data={data.newMessage}
      renderItem={({ item }) => (
        <View>
          <Text>{item.author.name}: {item.text}</Text>
        </View>
      )}
    />
  );
}

This code defines a subscription for new messages and uses the useSubscription hook to receive updates. The FlatList component is used to display the messages.

4. Use TypeScript for type safety

TypeScript is a strongly-typed language that can help to catch errors early and improve the overall quality of our code. Using TypeScript with GraphQL can help to ensure that our queries and mutations are typed correctly, reducing the risk of runtime errors.

To use TypeScript with React Native and Apollo Client, we need to install the @apollo/client and graphql packages with their respective TypeScript packages:

npm install @apollo/client graphql @types/react @types/react-native @types/react-test-renderer --save

We can then define our queries and mutations with typed variables and results:

import { gql, useQuery } from '@apollo/client';

interface User {
  id: string;
  name: string;
  email: string;
}

interface GetUserQueryResult {
  user: User;
}

const GET_USER = gql`
  query getUser($id: ID!) {
    user(id: $id) {
      id
      name
      email
    }
  }
`;

function UserProfile({ userId }: { userId: string }) {
  const { loading, error, data } = useQuery<GetUserQueryResult>(GET_USER, {
    variables: { id: userId },
  });

  if (loading) {
    return <Text>Loading...</Text>;
  }

  if (error) {
    return <Text>Error :(</Text>;
  }

  return (
    <View>
      <Text>{data.user.name}</Text>
      <Text>{data.user.email}</Text>
    </View>
  );
}

This code defines a User interface and a GetUserQueryResult interface that are used to type the variables and result of the GET_USER query. The useQuery hook is also typed with the GetUserQueryResult interface to ensure type safety.

5. Use Apollo Server for server-side caching

Apollo Server is a GraphQL server that can help to improve performance by caching data on the server-side. This can reduce the number of database queries and network requests required to fetch data, resulting in faster response times.

To use Apollo Server, we need to define a schema and resolvers for our data:

const { ApolloServer, gql } = require('apollo-server');

const typeDefs = gql`
  type Query {
    hello: String
    user(id: ID!): User
  }

  type User {
    id: ID!
    name: String!
    email: String!
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!',
    user: (_, { id }) => {
      // fetch user data from database
    },
  },
};

const server = new ApolloServer({
  typeDefs,
  resolvers,
});

server.listen().then(({ url }) => {
  console.log(`Server ready at ${url}`);
});

This code defines a schema with a hello query and a user query that accepts an id argument. The resolvers object defines the logic for each query.

When a client sends a query to the server, Apollo Server will check its cache to see if it has already received a similar query. If the data is in the cache, it will be returned immediately. Otherwise, the query will be executed and the result will be added to the cache for future use.

Conclusion

Using GraphQL with React Native can help to simplify data management and improve performance in our applications. By following best practices such as using Apollo Client for state management, using fragments to improve performance, using subscriptions for real-time updates, using TypeScript for type safety, and using Apollo Server for server-side caching, we can build robust and efficient applications that provide a great user experience.