How to use react-query to replace context

In React, the Context API is a mechanism for passing data through the component tree, which can avoid the inconvenience of passing data through multiple layers via props. However, when handling server state (such as remotely loaded data) in an application, React Query provides a more powerful and efficient way to synchronize and manage this state.

React Query is a powerful data synchronization library primarily used for handling the retrieval, caching, synchronization, and updating of asynchronous data. Using React Query can replace the use of Context API in certain scenarios, especially when data needs frequent updates, caching is required, and the scope of state sharing is limited.

Here are the steps and reasons for using React Query instead of Context:

1. Server State Management:

   • Using React Query's useQuery and useMutation hooks, you can easily fetch data from the server and provide features like caching, automatic refetching, and state updates.
   • For example, if you have a user list that needs to be accessed in multiple components and may be updated, you can create a query hook to fetch and cache this list.

2. Avoiding Unnecessary Rendering:

   • Context API re-renders all consumers whenever the value changes, regardless of whether they actually need the data. React Query, through caching and data selection, can avoid unnecessary re-renders of unrelated components.
   • For example, you can use the select option to only choose a part of the query data, so only components dependent on that part re-render when data updates.

3. Data Synchronization and Updates:

   • React Query provides automatic refetching functionality, allowing you to specify data refresh strategies, such as fetching the latest data when the window regains focus or network reconnects.
   • For example, if your application displays a task list, it can automatically detect changes when a task is added in another tab and update the list.

4. Simpler Data Dependency Management:

   • With React Query, you can easily set up data dependencies, such as triggering another query after one completes.
   • For example, if you need to first fetch a user ID and then use it to fetch user details, you can use React Query's useQuery and set dependencies to achieve this.

5. Built-in Error Handling and Loading States:

   • React Query provides status flags in the hook return values, such as isLoading, isError, and error, making error handling and displaying loading states very intuitive.
   • For example, while loading user data, you can directly use isLoading to show a loading indicator, and isError and error to display error messages.

6. Developer Tools:

   • React Query provides a developer tool that allows you to observe query states and cache changes during development, which is not available with Context API.
   • For example, you can use React Query Devtools to inspect cached data, see when data changes, and debug issues.

It's important to note that while React Query excels at managing server state, Context API remains very useful for managing global application state, such as themes or current language, which do not involve server-side operations. In practice, React Query and Context API may coexist, each handling the state parts they are best suited for.