useDocument causes infinite loops

[ItsAnoch]

When using useEffect and useDocument infinite loops.

This is a custom hook I have to have up to date use data.

export function useUserData(): UseUserDataReturn {
  const { data: session, status } = useSession();

  const documentRef = useCallback(() => {
    return session?.user?.id ? doc(db, 'users', session.user.id) : null;
  }, [session?.user?.id]);

  const options = useMemo(() => ({
    snapshotListenOptions: { includeMetadataChanges: true },
  }), []);

  const [value, loading, error] = useDocument(documentRef(), options);

  const userData = value?.data() as User | null;

  return {
    session,
    status,
    userData,
    loading,
    error
  };
}

If I create a separate state and use useEffect to update that state when userData changes it causes an infinite loop. Here's an example.

const { userData } =  useUserData();
const [ cart, setCart ] = useState<string[]>([]);

useEffect(() => {
   if (!userData) return;
   setCart( Object.keys( userData.cart ) );
}, [ userData ]);

Am I doing something wrong? Is there a way to fix this?

[vpishuk]

It looks like this package is not maintained for a lon time. I created a new package instead: https://github.com/vpishuk/react-query-firebase. It is missing documentation for now, but you can reach out to me and I would be happy to help you to start using it.

[BinDohry]

(This response was created with the help of Google Gemini.)

Hello! I took a look at your code, and it appears the infinite loop is being caused by a common React issue related to referential equality, rather than a bug in the react-firebase-hooks library itself.

The problem originates from how the DocumentSnapshot.data() method works.

The Cause: Referential Equality

The core of the issue is in this line within your useUserData hook:

const userData = value?.data() as User | null;

The .data() method creates and returns a brand new object in memory every time it's called. This happens on every single render, even if the underlying data from Firestore hasn't changed.

This creates the following infinite loop:

1. Render 1: useUserData runs and creates a userData object (let's call it Object_A).
2. Effect Runs: Your useEffect sees Object_A in its dependency array [userData] and runs its logic.
3. State Update: setCart() is called, which triggers a component re-render.
4. Render 2: useUserData runs again. Even though the value snapshot is the same, .data() is called again, creating a new userData object (Object_B).
5. Dependency Check Fails: React compares the dependencies. Since Object_A !== Object_B (they are different objects in memory), React thinks the dependency has changed and runs the effect again.
6. This cycle repeats indefinitely. 🔁

The Solution: useMemo

To solve this, you can wrap the .data() call in a useMemo hook. This tells React to memoize (remember) the userData object and only create a new one if the value (the DocumentSnapshot itself) has actually changed.

Here is the corrected useUserData hook:

import { useMemo, useCallback } from 'react'; // Make sure to import useMemo
import { doc } from 'firebase/firestore';
import { useDocument } from 'react-firebase-hooks/firestore';
import { useSession } from 'next-auth/react';
// ... other imports for your project (db, User, etc.)

export function useUserData(): UseUserDataReturn {
  const { data: session, status } = useSession();

  const documentRef = useCallback(() => {
    return session?.user?.id ? doc(db, 'users', session.user.id) : null;
  }, [session?.user?.id]);

  const options = useMemo(() => ({
    snapshotListenOptions: { includeMetadataChanges: true },
  }), []);

  const [value, loading, error] = useDocument(documentRef(), options);

  // FIX: Memoize the result to ensure a stable object reference
  const userData = useMemo(() => value?.data() as User | null, [value]);

  return {
    session,
    status,
    userData, // This reference is now stable across renders
    loading,
    error
  };
}

This change ensures that the userData object reference remains stable across re-renders, breaking the infinite loop. Your useEffect will now only run when the document data in Firestore actually changes.

This is also why useDocumentData likely works for you without this issue; it's a higher-level hook that handles this memoization for you under the hood. When using the lower-level useDocument, you have to manage it yourself.

Hope this helps!