Retrieve all documents from a collection in Firestore web in real-time

Question

Retrieve all documents from a collection in Firestore web in real-time

Is it possible to retrieve all elements from a collection in real-time?

I have been searching for documentation on this topic, but haven't found anything. While I know it's feasible to fetch all data from a collection, I am unsure if it can be done in real-time.

The code snippet below currently only works once when the page is loaded:

const querySnapshot = await getDocs(collection(db, "users"));
querySnapshot.forEach((doc) => {
  console.log(`${doc.id} => ${doc.data()}`);
});

Are you aware of any method to achieve similar results in real-time using "onSnapshot"? Additionally, I am utilizing Next 13 if that provides any additional context or assistance.

javascript firebase google-cloud-firestore next.js

Answer 1

Answer №1

Refer to the documentation on Getting realtime updates with Cloud Firestore - Listening to multiple documents in a collection. Utilize the onSnapshot() method to establish a subscription.

You can provide any query or document reference to the onSnapshot() function, even an unqualified collection reference.

The snapshot handler receives a new query snapshot whenever there are changes in the query results (such as when a document is added, removed, or modified).

In a React setting, it's recommended to implement this within an effect hook where you have the option to invoke the returned unsubscribe function during cleanup.

Here's an example:

useEffect(
  () =>
    onSnapshot(collection(db, "users"), (snapshot) => {
      snapshot.forEach((doc) => {
        // doc.data() is always defined for query doc snapshots
        console.log(doc.id, " => ", doc.data());
      });
    }),
  []
);

Answer 2

Refer to the documentation on Getting realtime updates with Cloud Firestore - Listening to multiple documents in a collection. Utilize the onSnapshot() method to establish a subscription.

You can provide any query or document reference to the onSnapshot() function, even an unqualified collection reference.

The snapshot handler receives a new query snapshot whenever there are changes in the query results (such as when a document is added, removed, or modified).

In a React setting, it's recommended to implement this within an effect hook where you have the option to invoke the returned unsubscribe function during cleanup.

Here's an example:

useEffect(
  () =>
    onSnapshot(collection(db, "users"), (snapshot) => {
      snapshot.forEach((doc) => {
        // doc.data() is always defined for query doc snapshots
        console.log(doc.id, " => ", doc.data());
      });
    }),
  []
);

Answer 3

Answer №2

Here is a custom Hook that I created to achieve this task. It monitors changes in the database and retrieves all documents from the specified collection.

import { useState, useEffect } from 'react';
import { projectFirestore } from '../firebase/config';
import { collection, onSnapshot } from "firebase/firestore";

const useFirestore = (coll) => {
    const [docs, setDocs] = useState([]);

    useEffect(() => {
        const unsubscribe = onSnapshot(collection(projectFirestore, coll), (snapshot) => {
            const documents = snapshot.docs
                .sort((a, b) => b.data().createdAt - a.data().createdAt)
                .map((doc) => ({ ...doc.data(), id: doc.id }));

            setDocs(documents);
        });

        return () => unsubscribe();
    }, []);

    return {docs};
}

export default useFirestore;

projectFirestore represents the Firestore SDK instance used for interacting with the database. It's common practice to refer to it as db.

Below is an illustration of how this function can be utilized to populate an image grid component,

import React from "react";
import useFirestore from "../hooks/useFirestore";

const ImageGrid = () => {
    const {docs} = useFirestore("images");

    return (
        <div className="img-grid">
            {docs && docs.map((doc) => (
                <div className="img-wrap" key={doc.id}>
                    <img src={doc.url} alt="uploaded pic"/>
                </div>
            ))}
        </div>
    );
}

export default ImageGrid;

Answer 4

Here is a custom Hook that I created to achieve this task. It monitors changes in the database and retrieves all documents from the specified collection.

import { useState, useEffect } from 'react';
import { projectFirestore } from '../firebase/config';
import { collection, onSnapshot } from "firebase/firestore";

const useFirestore = (coll) => {
    const [docs, setDocs] = useState([]);

    useEffect(() => {
        const unsubscribe = onSnapshot(collection(projectFirestore, coll), (snapshot) => {
            const documents = snapshot.docs
                .sort((a, b) => b.data().createdAt - a.data().createdAt)
                .map((doc) => ({ ...doc.data(), id: doc.id }));

            setDocs(documents);
        });

        return () => unsubscribe();
    }, []);

    return {docs};
}

export default useFirestore;

projectFirestore represents the Firestore SDK instance used for interacting with the database. It's common practice to refer to it as db.

Below is an illustration of how this function can be utilized to populate an image grid component,

import React from "react";
import useFirestore from "../hooks/useFirestore";

const ImageGrid = () => {
    const {docs} = useFirestore("images");

    return (
        <div className="img-grid">
            {docs && docs.map((doc) => (
                <div className="img-wrap" key={doc.id}>
                    <img src={doc.url} alt="uploaded pic"/>
                </div>
            ))}
        </div>
    );
}

export default ImageGrid;

Retrieve all documents from a collection in Firestore web in real-time

Answer №1

Answer №2

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