Understanding the React Query Issue: How to Solve Duplicate Requests and Outdated Responses

Learn why `React Query` spawns duplicate requests with outdated responses and explore effective solutions to ensure accurate data fetching in your React applications.
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Understanding the React Query Issue: How to Solve Duplicate Requests and Outdated Responses

If you're working with React Query and notice that your application is sending duplicate network requests for the same data, it can be quite puzzling. You're not alone in this; many developers encounter this issue when dealing with dynamic data changes. In this guide, we're going to break down a specific scenario involving duplicate requests and provide a clear solution.

The Problem: Duplicate Requests and Old Responses

Imagine you have a component structure where a parent component fetches data and conditionally renders a child component based on the data's state. In this case, when the post's status is updated to 'published', the application unexpectedly sends two requests. The first request returns the outdated status, while the second request retrieves the updated version. This behavior can lead to confusion and unsatisfactory user experiences.

Setup Example

Here's a simplified outline of the related code:

Parent Component

[[See Video to Reveal this Text or Code Snippet]]

Child Component

[[See Video to Reveal this Text or Code Snippet]]

The Violation of React Query's Behavior

This scenario unfolds because the ChildComponent fetches data right after ParentComponent triggers an update via the mutation function. As a result, while the mutation request is in progress, the ChildComponent mounts and initiates its own data fetch. This leads to having one request return the old data and the next one returning the new status, resulting in confusion.

The Solution: Optimizing Data Fetching with React Query

To resolve the issue of seeing two requests and outdated responses, consider implementing the following changes:

Step 1: Remove OnMutate Functionality

By default, React Query automatically refetches data when a component mounts. Therefore, you can remove the onMutate function from your mutation setup because it unnecessarily updates the cache before the actual API call. This premature cache update can trigger the undesired behavior.

Example of the Mutation Setup

Here's how the mutation can look without the onMutate:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Control Component Rendering Logic

To minimize the number of fetch requests, it’s best to control when components are rendered based on data availability. If the ChildComponent renders only when the required data is in the desired state (i.e., status is 'published'), it would not mount unnecessarily.

Example of Conditional Rendering

While you want to maintain the layout with the margin, you can adjust how components display as follows:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By removing the onMutate logic and controlling when components render, you can effectively manage how React Query handles data fetching and state updates. This approach minimizes unnecessary requests, yielding a smoother user experience and reducing confusion during data transitions.

Implementing these changes can significantly improve your React application’s efficiency and overall performance. Happy coding!