React Query for State Management in React Native

Mastering State Management in React Native with React Query

The Importance of State Management

State management is a crucial aspect of React Native development, as it enables you to handle mutable data in your components effectively. A state is a JavaScript object that can change over time, often as a result of user interactions. While simple local state management can be achieved using the setState method or the useState hook, managing shared state across components can become increasingly complex as your app grows.

The Role of State Management Libraries

This is where state management libraries come into play. There are numerous libraries available, each with its strengths and weaknesses. Two popular options are Context and Redux. Context provides a way to pass data through the component tree without prop drilling, while Redux is a powerful, framework-agnostic state management layer that offers a single global state object called the store.

Introducing React Query

React Query is a lightweight caching layer that lives in your application, providing a simple and efficient way to manage data fetching. As a data-fetching library, it’s agnostic to how you fetch your data, requiring only the promise returned by Axios or Fetch. React Query exports a useQuery hook for handling queries, which takes two parameters: a unique identifier and a fetcher function.

How React Query Works

The useQuery hook returns a query object, which contains several important states:

• isLoading or status === 'loading': The query has no data and is currently fetching.
• isError or status === 'error': The query encountered an error.
• isSuccess or status === 'uccess': The query was successful, and data is available.
• isIdle or status === 'idle': The query is currently disabled.

Beyond these primary states, the query object also contains additional information, such as error messages, data, and whether the query is fetching in the background.

Getting Started with React Query and React Native

To get started with React Query and React Native, you’ll need:

• Basic knowledge of JavaScript
• Basic knowledge of React and React Native

Create a new React Native application using Expo CLI, and install the required dependencies. Then, set up your navigation and create a constants folder with a color.js file inside it.

Building a Simple Application with React Query

Next, create a Posts and Post components, and set up React Query by modifying your App.js file. Create a QueryClient to interact with the cache, and use the QueryClientProvider component to connect and provide the QueryClient to your app.

Creating Reusable Components

Create a components folder with a Text.js file inside it, and add the following code to create a reusable Text component with default style. Then, create the app’s screens, including the Posts.js and Post.js files.

Fetching Data with React Query

Create two folders, namely screens and hooks. In the hooks folder, create a usePosts.js file and add the following code to fetch data for the Posts screen. Also, create a usePost.js file to fetch data for the Post screen.

Rendering Data with React Query

In the screens folder, create two files, namely Posts.js and Post.js. Add the following code to the Posts.js file to render a loading text if isLoading is true, and render the post list using FlatList if isSuccess is true. In the Post.js file, fetch the post clicked on by the user as a route param and fetch its comment using its ID.

The Benefits of React Query

React Query offers a gain in developer experience (DX) and user experience (UX), as well as improved app performance. By caching data under the hood, React Query makes subsequent load times “instant,” resulting in a faster and more responsive app.

Conclusion

React Query is a powerful and efficient data-fetching library that simplifies state management in React Native applications. With its easy-to-use API and robust features, React Query is an excellent choice for managing complex state in your React Native app.