How do I update a single record in react-query outside of mutation?

When using React Query, the typical approach for data updates involves interacting with the backend through Mutations, which automatically refreshes or refetches the data. However, there are scenarios where you need to update cached data directly on the client side without involving the backend. In such cases, you can leverage the queryClient.setQueryData method from React Query.

Updating Data with setQueryData

The setQueryData method enables direct modification of cached data. This approach provides immediate user feedback without waiting for server responses, which is highly beneficial for enhancing user experience. Below are the specific steps to implement this method:

1. Determine the Query Key for the Data to Update: First, identify which query's cache needs updating. Each data request using useQuery or related hooks has a unique query key.

2. Update Data Using setQueryData: Invoke the setQueryData method via the queryClient object, supplying the relevant query key along with either the new data or a function to modify the data.

Example Code

Suppose you have a query for fetching user information with the query key ['user', userId], and you want to update this data immediately after the user changes their nickname. Here is an example implementation:

jsx
import { useQuery, useQueryClient } from 'react-query';

function UserProfile({ userId }) {
    const queryClient = useQueryClient();
    const { data: user } = useQuery(['user', userId], fetchUserById);

    const updateUserNickname = newNickname => {
        // Update backend data
        updateUserOnServer(userId, { nickname: newNickname }).then(updatedUser => {
            // Immediately update the cached user data
            queryClient.setQueryData(['user', userId], updatedUser);
        });
    };

    return (
        <div>
            <h1>{user?.nickname}</h1>
            <button onClick={() => updateUserNickname('new nickname')}>Update Nickname</button>
        </div>
    );
}

In this example, we first update the user information via the backend API. Once the backend confirms the update, we use setQueryData to immediately refresh the cached data. This allows the user interface to display the new nickname instantly without waiting for a refetch.

Summary

Using setQueryData enables efficient direct updates of cached data in React Query on the client side, significantly improving user experience. This method is particularly valuable for real-time scenarios, reducing server load and minimizing delays caused by network latency.