Firestore query is returning empty results upon page initialization, but provides data upon subsequent re-renders in React Native

Question

Firestore query is returning empty results upon page initialization, but provides data upon subsequent re-renders in React Native

ISSUE

I'm encountering an issue where I am unable to fetch documents from a Firestore collection when the page loads. Despite executing the query multiple times during loading, it does not return any results. However, if I trigger the query by changing a state through a page button, then it successfully retrieves the results.

QUERIES

I suspect that the problem might be related to Firebase initialization. How can I ensure that the query functions properly during page load so that it can display information fetched from the database?

CODE DETAILS

My code includes firebase.js, where all the database-related code is stored. Additionally, I have a dashboard component that executes the query, sets the results as states, and passes them to child components for rendering purposes. Despite calling the query repeatedly on page load, no results are displayed. It's only after some delay and re-calling the query that results are obtained.

firebase.js

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(Insert your unique content here)
...

Dashboard.js

...
(Insert your unique content here)
...

https://i.sstatic.net/kOdgl.png

javascript firebase react-native google-cloud-firestore

Answer 1

Answer №1

Your problem seems to lie within the async useEffect hook you are using.

When utilizing async functions in useEffect, make sure to handle the return value correctly as it will be a Promise rather than just undefined or a cleanup function.

To address this issue, consider refactoring your code as shown below to avoid returning a Promise:

useEffect(() => {
    // Check for user data
    const fetchUserData = async () => {
      user.providerData.forEach((userInfo) => {
        setEmail(userInfo.email);
      });
    }
    
    fetchUserData();
}, [])

Answer 2

Your problem seems to lie within the async useEffect hook you are using.

When utilizing async functions in useEffect, make sure to handle the return value correctly as it will be a Promise rather than just undefined or a cleanup function.

To address this issue, consider refactoring your code as shown below to avoid returning a Promise:

useEffect(() => {
    // Check for user data
    const fetchUserData = async () => {
      user.providerData.forEach((userInfo) => {
        setEmail(userInfo.email);
      });
    }
    
    fetchUserData();
}, [])

Answer 3

Answer №2

After some troubleshooting, I finally cracked the code.

To optimize my application performance, I decided to put it in a loading state. While in this state, I divided my database calls (one for user authentication and the other for fetching notifications) into two separate useEffect functions. Additionally, I implemented a third useEffect function to toggle off the loading state after data had been successfully retrieved. This strategy ensured that the states were properly populated with data before rendering the entire page.

//Fetching user data on initial load
useEffect(() => {
  const getUserInfo = async () => {
    await user.providerData.forEach((userInfo) => {
      setEmail(userInfo.email);
    });
  };

  //Checking if user info is empty
  if (email == "") {
    getUserInfo();
  }
}, []);

//Fetching notifications once user data is available
useEffect(() => {
  //Fetching user notifications
  async function getNotifications() {
    console.log("User email: ", email);
    await queryDatabase(
      setQueryByEmail(setCollection("notifications"), email),
      setNotifications
    ); //Creating collection reference, querying for user's notifications, and setting setNotification with an array of JSON objects
  }

  getNotifications();
}, [email]);

//Setting notification quantity and turning off loading state when notifications are fetched
useEffect(() => {
  setNotificationQuantity(notifications.length); //Displaying the number of notifications in the red circle
  setLoading(false);
}, [notifications]);

Answer 4

After some troubleshooting, I finally cracked the code.

To optimize my application performance, I decided to put it in a loading state. While in this state, I divided my database calls (one for user authentication and the other for fetching notifications) into two separate useEffect functions. Additionally, I implemented a third useEffect function to toggle off the loading state after data had been successfully retrieved. This strategy ensured that the states were properly populated with data before rendering the entire page.

//Fetching user data on initial load
useEffect(() => {
  const getUserInfo = async () => {
    await user.providerData.forEach((userInfo) => {
      setEmail(userInfo.email);
    });
  };

  //Checking if user info is empty
  if (email == "") {
    getUserInfo();
  }
}, []);

//Fetching notifications once user data is available
useEffect(() => {
  //Fetching user notifications
  async function getNotifications() {
    console.log("User email: ", email);
    await queryDatabase(
      setQueryByEmail(setCollection("notifications"), email),
      setNotifications
    ); //Creating collection reference, querying for user's notifications, and setting setNotification with an array of JSON objects
  }

  getNotifications();
}, [email]);

//Setting notification quantity and turning off loading state when notifications are fetched
useEffect(() => {
  setNotificationQuantity(notifications.length); //Displaying the number of notifications in the red circle
  setLoading(false);
}, [notifications]);

Firestore query is returning empty results upon page initialization, but provides data upon subsequent re-renders in React Native

Answer №1

Answer №2

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