Mastering React Query: How to Avoid Excessive Re-renders When Fetching Data

Are you struggling with excessive re-renders in React when using React Query? Discover effective strategies to prevent this issue and smoothly manage your app's state.
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Mastering React Query: How to Avoid Excessive Re-renders When Fetching Data

When building web applications in React, managing state can sometimes feel overwhelming—especially when API calls are involved. One common issue developers face is excessive re-renders when using hooks to manage state along with React Query. In this guide, we'll explore a specific scenario and provide effective solutions to keep your app performant and your code clean.

The Problem: Excessive Re-renders in React

Consider a situation where you are using React Query to fetch a list of schedule dates from an API. You want to update your component's state with these dates but are encountering issues because calling the state setter during the render phase is leading to too many re-renders. Here's a snippet of the code that illustrates the situation:

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As a developer, it's crucial to understand that invoking state setters outside of the appropriate lifecycle methods can lead to issues within your component. The main takeaway here is to avoid calling setDates directly during the render process, as it violates React's principle of having pure render functions.

The Solution: Where to Update State

Now, let’s break down effective strategies you can use to manage state updates while using React Query without causing excessive re-renders.

1. Using useEffect Hook

The React useEffect hook is designed for side effects, including data fetching, subscriptions, or manually modifying the DOM. To prevent re-renders, you can utilize useEffect to update your state when existingSchedules changes.

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2. Using onSuccess Callback of useQuery

Another approach is to leverage the onSuccess callback provided by React Query’s useQuery. This allows you to execute a function after successfully fetching data, making it an ideal place to set your state.

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Both methods ensure that your state updates are conducted within the proper lifecycle of your component, greatly reducing the risk of triggering excessive re-renders.

Clarifying State Management in React

In the realm of state management, it's essential to differentiate between client state and server state. React Query is particularly effective at managing server state. Therefore, consider structuring your component state as follows:

Store User Selections in State: Keep user-selected dates in your component’s local state using useState.

Handle Server Data with React Query: Let React Query manage existing schedules without duplicating that data in local component state.

Here's an example of how you can combine these two approaches seamlessly:

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Conclusion

In summary, managing states while utilizing React Query is all about understanding the right hooks and timing. Avoid setting state directly during the render phase to prevent excessive re-renders. Instead, use either the useEffect hook or the onSuccess callback to manage your data effectively. With these strategies, you can ensure your React application remains performant and your code stays clean and organized.

With practice and implementation, you will ensure a smoother experience both for yourself as a developer and for the users of your application. Happy coding!