How to Fix isLoading State in a React Custom Hook for Firebase Fetching

Learn how to properly manage loading states in your custom React hooks when fetching data from Firebase Firestore.
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How to Fix isLoading State in a React Custom Hook for Firebase Fetching

In the world of web development, particularly when using Firebase with React, it's essential to manage loading states effectively. One common issue that developers face is improper handling of loading states, especially when creating custom hooks to fetch data. In this post, we'll explore a specific problem: why the isUserLoading state in a custom hook is always returning false, despite being set to true during data fetching. Let's dive in!

Understanding the Problem

You have a custom hook named useCurrentUser that is designed to fetch user data from Firebase Firestore. Within this hook, you attempt to manage loading states using isUserLoading and other variables. However, you encounter the issue where isUserLoading remains false throughout the lifecycle of your hook, even though you set it to true before fetching the data. Why is this happening?

The Root Cause

The key to understanding this issue lies in the behavior of the onSnapshot function from Firebase. Unlike other data fetching methods that return a promise, onSnapshot is designed to listen for changes in real-time and returns a function to unsubscribe from those updates. Because you're trying to await a function that doesn't return a promise, the finally block in your try-catch structure executes immediately, resetting isUserLoading to false before the data is actually retrieved.

The Solution

To resolve the issue of isLoading always being false, we need to adjust how the onSnapshot function is used within your hook. Here's a revised version of the useCurrentUser hook that correctly handles the loading state:

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Key Changes Explained

Simplified Loading Management: The loading state is now initiated as true and set to false immediately after data is received. This matches the expected user experience.

Real-time Data Handling: By managing the state directly within the onSnapshot callback instead of a try-catch, you ensure that any changes in the Firestore document trigger the correct loading state changes.

Error Handling: Errors that occur during the snapshot listener are handled properly, allowing isUserLoading to be set to false if something goes wrong.

Dependency Management: The userId variable is passed as a dependency to the useEffect hook to ensure the hook reacts to any changes.

Conclusion

By applying these adjustments, you can effectively manage the isLoading state in your React custom hook when fetching data from Firebase Firestore. This pattern not only enhances user experience but also ensures your application handles real-time data efficiently.

If you've encountered similar issues or have other questions about React and Firebase, feel free to ask in the comments below! Your feedback is always appreciated.