React Query is a full-featured library that gives you explicit control over data fetching and state management.

Suspense, on the other hand, is a React-native solution that abstracts the loading logic so your component code remains very clean.

how React Query can manage dependencies between queries.

Example Scenario: User Dashboard

Scenario Details:

1. Fetch User Data:

   The first query fetches the current user’s information from your API endpoint (e.g., /api/user).

2. Fetch User Posts:

   Once the user data is available, you use the user's ID to fetch the posts that the user has created (e.g., /api/users/:userId/posts).

   This query is made dependent on the user data—using the React Query option enabled to ensure it only runs after the user data is successfully loaded.

Code Example

import React from 'react';
import { useQuery } from 'react-query';
function UserDashboard() {
  // First, fetch user data
  const {
    data: user,
    isLoading: isUserLoading,
    error: userError,
  } = useQuery('user', fetchUser);

  // Then, fetch user posts once the user data is available
  const {
    data: posts,
    isLoading: isPostsLoading,
    error: postsError,
  } = useQuery(
    ['posts', user?.id],
    () => fetchPostsByUser(user.id),
    {
      enabled: !!user, // Run this query only if user data exists
    }
  );

  if (isUserLoading || isPostsLoading) return <div>Loading...</div>;
  if (userError) return <div>Error loading user: {userError.message}</div>;
  if (postsError) return <div>Error loading posts: {postsError.message}</div>;

Explanation

• Fetching User Data:

  The first useQuery is responsible for fetching user information. While this query is loading, the component shows a loading state. If it encounters an error, it displays an error message.

• Dependent Query for Posts:

  The second useQuery fetches posts based on the user ID. The key here is the enabled option:

  • By setting enabled: !!user, you ensure that the posts query runs only when the user data is available.
  • Until the user data is fetched, this query stays inactive, which avoids unnecessary errors or API calls.

• Handling Asynchronous Data:

  This pattern of dependent queries allows you to handle scenarios where multiple API calls depend on one another, reducing complexity in your component logic. React Query manages caching, background updates, and even error states for each query separately.