Samkit Jain | Personal Portfolio

Introduction:

When working with data fetching and state management in React applications, @tanstack/react-query is a powerful library that simplifies the process. However, one common issue that developers may encounter is the reset of state when there is a change in query parameters and component rerenders. In this article, we will explore this problem and discuss how to prevent state resets using the features provided by @tanstack/react-query.

Understanding the Issue:

Imagine a scenario where you have a component that fetches data based on query parameters. Whenever the query parameters change, such as when the user selects different options or filters, the component’s state resets, causing a poor user experience. This happens because the query is treated as a new request, resulting in the previous data being discarded and the component starting from scratch.

Using Placeholder Data:

@tanstack/react-query offers a solution to this issue through the placeholderData option. By providing placeholder data, you can maintain the existing state while fetching the updated data. This ensures a smooth transition for the user and avoids abrupt state resets.

Implementation Example:

Let’s take a look at how you can implement this solution:

import { useQuery } from '@tanstack/react-query';

const fetchData = async (params) => {
  // Perform data fetching based on the params
  // Return the fetched data
};

const MyComponent = ({ queryParameters }) => {
  const { data } = useQuery(\['myQueryKey', queryParameters\], () => fetchData(queryParameters), {
    placeholderData: previousData, // Use previousData as placeholder
  });

  // Render the component using the data
};

By passing placeholderData with the previous data to the useQuery hook, you ensure that the existing data is displayed until the updated data is fetched.

Preserving Previous Data:

In addition to placeholderData, @tanstack/react-query also provides the keepPreviousData flag. When set to true, it retains the previous data in the cache, even when a new request is triggered due to changes in query parameters. This allows you to display the previous data while fetching the new data in the background.

const { data } = useQuery(\['myQueryKey', queryParameters\], () => fetchData(queryParameters), {
  placeholderData: previousData,
  keepPreviousData: true, // Preserve previous data
});

By leveraging the keepPreviousData flag, you can ensure that the state remains intact during query parameter changes, providing a seamless user experience.

Conclusion:

When using @tanstack/react-query, you can overcome the issue of state resets when component rerenders by utilizing the placeholderData option and the keepPreviousData flag, you can maintain the existing state while fetching updated data in the background. This approach ensures a smooth user experience and prevents unnecessary disruptions in your application.