How to get currently active queryKeys in react- query

React Query is a powerful data synchronization library for managing server state in React applications. It simplifies the process of data fetching, caching, synchronization, and updates by providing a suite of hooks and utilities.

In React Query, each query is identified by a unique key called queryKey. This queryKey is typically a string or an array consisting of strings and objects. The queryKey plays a crucial role in data fetching, caching, and invalidation.

To retrieve the currently active queryKeys, you can use the developer tools provided by React Query or programmatically access them via React Query's API.

The following example demonstrates how to use the useQuery hook to fetch data and its corresponding queryKey:

javascript
import { useQuery } from 'react-query';

function fetchUserData(userId) {
  return fetch('https://my.api/user/' + userId).then(res => res.json());
}

function UserProfile({ userId }) {
  // In this example, the queryKey is ['user', userId], which consists of a string and a dynamic userId
  const { data, error, isLoading } = useQuery(['user', userId], () => fetchUserData(userId));

  if (isLoading) return 'Loading...';
  if (error) return 'An error has occurred: ' + error.message;

  // Render user data
  return (
    <div>
      <h1>{data.name}</h1>
      <p>{data.bio}</p>
    </div>
  );
}

In the above example, the first argument of the useQuery hook is the queryKey (in this case, ['user', userId]). The queryKey is typically a string or an array, which determines the uniqueness of the query and is critical for the caching mechanism.

If you want to retrieve all active query keys in the application, you can use the useQueries hook or the query cache object queryCache. For example:

javascript
import { useQueryClient } from 'react-query';

function ListActiveQueries() {
  const queryClient = useQueryClient();

  // Retrieve information about all queries in the cache
  const queriesInfo = queryClient.getQueriesData();

  // Extract all active query keys
  const activeQueryKeys = queriesInfo.map(query => query.queryKey);

  // Render all active query keys
  return (
    <ul>
      {activeQueryKeys.map(key => (
        <li key={key}>{JSON.stringify(key)}</li>
      ))}
    </ul>
  );
}

In this example, we use the useQueryClient hook to obtain the current queryClient instance, then call the getQueriesData method to retrieve information about all queries in the cache. The getQueriesData method returns an array where each element contains detailed information about a query, including its queryKey. We then map this array to extract all queryKeys and render them in a list.

Note that queryKeys are often complex structures and may require serialization (as shown above with JSON.stringify) to be displayed correctly.