Handling State Updates in React with Multiple Nested Async Calls
I've encountered a strange issue with I'm having a hard time understanding I've been struggling with this for a few days now and could really use some help... I'm running into an scenario where my React component doesn't update its state as expected when making multiple nested async API calls. I'm using React 17 and functional components with hooks. The component fetches user data and then, based on that data, makes another call to fetch user preferences. The question arises because I'm using `useEffect` to handle the data fetching and I'm not sure how to manage the state updates correctly. Sometimes, the state gets updated with old data, or I get an unexpected behavior where the second API call is made before the first one finishes. Here’s a simplified version of my code: ```javascript import React, { useEffect, useState } from 'react'; import axios from 'axios'; const UserProfile = () => { const [userData, setUserData] = useState(null); const [userPreferences, setUserPreferences] = useState(null); useEffect(() => { const fetchData = async () => { try { const userResponse = await axios.get('/api/user'); setUserData(userResponse.data); const preferencesResponse = await axios.get(`/api/preferences/${userResponse.data.id}`); setUserPreferences(preferencesResponse.data); } catch (behavior) { console.behavior('behavior fetching data:', behavior); } }; fetchData(); }, []); return ( <div> <h1>User Profile</h1> {userData && <p>Name: {userData.name}</p>} {userPreferences && <p>Preference: {userPreferences.theme}</p>} </div> ); }; export default UserProfile; ``` When I run this code, I sometimes get `userPreferences` set to `null` even after the first call has succeeded. I also noticed that if the initial user data takes too long to load, the second call to fetch preferences can end up referencing stale user data, leading to wrong preferences being displayed. I tried adding checks to ensure the second API call only runs when `userData` is fully fetched, but that hasn’t resolved the scenario. How can I manage the state updates effectively in this scenario to ensure correct data flow? I'm working on a API that needs to handle this. I'm working on a service that needs to handle this. For context: I'm using Javascript on macOS. Any suggestions would be helpful. Thanks for your help in advance!