How to use firebase auth and Cloud Firestore from different components as a single firebase App

Question

I am trying to use firebase in my React project to provide the auth and database functionalities.

In my App.js I have

import app from "firebase/app";
import "firebase/auth";
app.initializeApp(firebaseConfig);

In my other components called <Component /> rendered by App.js I have this to initialize the database

import app from "firebase/app";
import "firebase/firestore";
const db = app.firestore();

However this time I got this error

Uncaught FirebaseError: Firebase: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp() (app/no-app).

So I tried to put app.initializeApp(firebaseConfig); in this component too but I got a new error again to tell me I instantiated twice.

Uncaught FirebaseError: Firebase: Firebase App named '[DEFAULT]' already exists (app/duplicate-app).

So one workaround I came up with is to create a context at App.js and right after app.initializeApp(firebaseConfig); I created the database by const db = app.firestore(); and pass the value to the context and let the <Component /> to consume. However I don't know if this is a good solution or not.

My question is different from How to check if a Firebase App is already initialized on Android for one reason. I am not trying to connect to a second Firebase App as it was for that question. There is only one Firebase App for my entire project, to provide two services: auth and database.

I tried the solution from that question to use in <Component />

if (!app.apps.length) {
  app.initializeApp(firebaseConfig);
}

const db = app.firestore();

but it didn't work it still gives me Uncaught FirebaseError: Firebase: Firebase App named '[DEFAULT]' already exists (app/duplicate-app). error

Answer 1

You use different instances of Firebase in App and Component.

// firebaseApp.js
import firebase from 'firebase'
const config = {
    apiKey: "...",
    authDomain: "...",
    databaseURL: "....",
    projectId: "...",
    messagingSenderId: "..."
};
firebase.initializeApp(config);
export default firebase;

Than you can import firebase from firebaseApp.js and use it. More details here

Answer 2

You can use a context as you said or redux (using a middleware to initialize, and global state to keep the db):

// Main (for example index.js)
<FirebaseContext.Provider value={new Firebase()}>
    <App />
</FirebaseContext.Provider>

Firebase.js:

import app from 'firebase/app'
import 'firebase/firestore'

const config = {
  apiKey: process.env.API_KEY,
  databaseURL: process.env.DATABASE_URL,
  projectId: process.env.PROJECT_ID,
  storageBucket: process.env.STORAGE_BUCKET
}

export default class Firebase {
  constructor() {
    app.initializeApp(config)

    // Firebase APIs
    this._db = app.firestore()
  }

  // DB data API
  data = () => this._db.collection('yourdata')

  ...
}

FirebaseContext.js:

import React from 'react'

const FirebaseContext = React.createContext(null)

export const withFirebase = Component => props => (
  <FirebaseContext.Consumer>
    {firebase => <Component {...props} firebase={firebase} />}
  </FirebaseContext.Consumer>
)

Then you can use withFirebase in your container components:

class YourContainerComponent extends React.PureComponent {
  state = {
    data: null,
    loading: false
  }

  componentDidMount() {
    this._onListenForMessages()
  }

  _onListenForMessages = () => {
    this.setState({ loading: true }, () => {
      this.unsubscribe = this.props.firebase
        .data()
        .limit(10)
        .onSnapshot(snapshot => {
          if (snapshot.size) {
            let data = []
            snapshot.forEach(doc =>
              data.push({ ...doc.data(), uid: doc.id })
            )
            this.setState({
              data,
              loading: false
            })
          } else {
            this.setState({ data: null, loading: false })
          }
        })
     })
   })
  }

  componentWillUnmount() {
    if (this._unsubscribe) {
      this._unsubscribe()
    }
  }
}


export default withFirebase(YourContainerComponent)

You can see the whole code here: https://github.com/the-road-to-react-with-firebase/react-firestore-authentication and a tutorial here: https://www.robinwieruch.de/complete-firebase-authentication-react-tutorial/

If you implement it using redux, and redux-thunk you can isolate all firebase stuff in middleware, actions, and reducers (you can take ideas and sample here: https://github.com/Canner/redux-firebase-middleware ); and keep the business logic in your components so they do not need to know how your data collections are stored and managed. The components should know only about states and actions.

Answer 3

Make a file firebaseConfig.js in src/firebase directory for firebase configuration:

import firebase from 'firebase/app'; // doing import firebase from 'firebase' or import * as firebase from firebase is not good practice. 
import 'firebase/auth';
import 'firebase/firestore';

// Initialize Firebase
let config = {
    apiKey: process.env.REACT_APP_FIREBASE_API_KEY,
    authDomain: process.env.REACT_APP_FIREBASE_AUTH_DOMAIN,
    databaseURL: process.env.REACT_APP_FIREBASE_DATABASE_URL,
    projectId: process.env.REACT_APP_FIREBASE_PROJECT_ID,
    storageBucket: process.env.REACT_APP_FIREBASE_STORAGE_BUCKET,
    messagingSenderId: process.env.REACT_APP_FIREBASE_MESSAGING_SENDER_ID,
};
firebase.initializeApp(config);

const auth = firebase.auth();
const db = firebase.firestore();

const googleAuthProvider = new firebase.auth.GoogleAuthProvider();
const emailAuthProvider = new firebase.auth.EmailAuthProvider();

export { auth, firebase, db, googleAuthProvider, emailAuthProvider };

All you have to do in Component.js is:

import { db } from './firebase/firebaseConfig.js'; // Assuming Component.js is in the src folder

Store the api keys in a .env file in the root folder of the project (the parent of src ):

REACT_APP_FIREBASE_API_KEY=<api-key>
REACT_APP_FIREBASE_AUTH_DOMAIN=<auth-domain>
REACT_APP_FIREBASE_DATABASE_URL=<db-url>
REACT_APP_FIREBASE_PROJECT_ID=<proj-name>
REACT_APP_FIREBASE_STORAGE_BUCKET=<storage-bucket>
REACT_APP_FIREBASE_MESSAGING_SENDER_ID=<message-sender-id>

Answer 4

The error message you are receiving is valid and has to do with the order your modules are imported. ES6 modules are pre-parsed in order to resolve further imports before code is executed.

Assuming the very top of your App.js looks something like this:

import Component from '../component';
...

import app from "firebase/app";
import "firebase/auth";
app.initializeApp(firebaseConfig);

The problem here is that inside import Component from '.../component';

import app from "firebase/app";
import "firebase/firestore";
const db = app.firestore();

That code gets executed before you do:

app.initializeApp(firebaseConfig);

There's many ways to fix this problem including some solutions presented above and the proposal to just store your firebase config in a firebase-config.js and import db from that.

This answer is more about understanding what the problem was ... and as far as the solution I think your Context Provider is actually really good and commonly practiced.

More about es6 modules here

Firebase React Setup

Hope that helps.

Answer 5

The best way I have found to use firebase in react is to first initialize and export firebase to then execute the desired functions.

helper-firebase.js

import * as firebase from 'firebase/app';
import 'firebase/auth';
import 'firebase/firestore';

// Everyone can read client side javascript, no need to use an .env file
// I only used environment variables for firebase-admin
import { FIREBASE_CONFIG } from '../../config';

// Initialize Firebase
firebase.initializeApp(FIREBASE_CONFIG);
export const auth = firebase.auth();
export const provider = new firebase.auth.GoogleAuthProvider();
export const db = firebase.firestore();
export default firebase;

your-component.js

import {
  auth,
  provider,
  db,
} from '../../../helpers/helper-firebase';

...
componentDidMount() {
  this.usersRef = db.collection('users');
  // Look for user changes
  auth.onAuthStateChanged(this.authChanged);
}

authChanged(user) {
  // Set value on the database
  this.usersRef.doc(user.uid).set({
    lastLogin: new Date(),
  }, { merge: true })
    .then(() => {
       console.log('User Updated');
    })
    .catch((error) => {
       console.error(error.message);
    });
}

login() {
  auth.signInWithPopup(provider)
    .then((res) => {
      console.log(newUser);
    })
    .catch((error) => {
      console.error(error.message);
    })
}
...

But i would recommend use 'redux-thunk' to store data on state:

redux-actions.js

import {
  auth,
} from '../../../helpers/helper-firebase';

export const setUser = payload => ({
  type: AUTH_CHANGED,
  payload,
});

export const onAuthChange = () => (
  dispatch => auth.onAuthStateChanged((user) => {
    // console.log(user);
    if (user) {
      dispatch(setUser(user));
    } else {
      dispatch(setUser());
    }
  })
);

export const authLogout = () => (
  dispatch => (
    auth.signOut()
      .then(() => {
        dispatch(setUser());
      })
      .catch((error) => {
        console.error(error.message);
      })
  )
);

Answer 6

Here is a simple example of storing the signed-in user data from google OAuth into firestore collection.

Store firebase config in a separate file

firebase.utils.js

import firebase from 'firebase/app';
import 'firebase/firestore';
import 'firebase/auth';

//replace your config here
const config = {
  apiKey: '*****',
  authDomain: '******',
  databaseURL: '******',
  projectId: '******,
  storageBucket: '********',
  messagingSenderId: '*******',
  appId: '**********'
};

firebase.initializeApp(config);

export const createUserProfileDocument = async (userAuth) => {
  if (!userAuth) return;

  const userRef = firestore.doc(`users/${userAuth.uid}`);

  const snapShot = await userRef.get();

  if (!snapShot.exists) {
    const { displayName, email } = userAuth;
    const createdAt = new Date();
    try {
      await userRef.set({
        displayName,
        email,
        createdAt
      });
    } catch (error) {
      console.log('error creating user', error.message);
    }
  }

  return userRef;
};

export const auth = firebase.auth();
export const firestore = firebase.firestore();

const provider = new firebase.auth.GoogleAuthProvider();
provider.setCustomParameters({ prompt: 'select_account' });
export const signInWithGoogle = () => auth.signInWithPopup(provider);

App.js

 import React from 'react';
 import { auth, createUserProfileDocument, signInWithGoogle } from './firebase.utils';

 class App extends React.Component {
  constructor() {
    super();

    this.state = {
      currentUser: null
    };

   }

  unsubscribeFromAuth = null;

  componentDidMount() {
    this.unsubscribeFromAuth = auth.onAuthStateChanged(async userAuth => {
      if (userAuth) {
        const userRef = await createUserProfileDocument(userAuth);

        userRef.onSnapshot(snapShot => {
          this.setState({
            currentUser: {
              id: snapShot.id,
              ...snapShot.data()
            }
          });

          console.log(this.state);
        });
      }

      this.setState({ currentUser: userAuth });
    });
  }

  componentWillUnmount() {
    this.unsubscribeFromAuth();
  }

  render() {
   return(
     <React.Fragment>
       { this.state.currentUser ? 
          (<Button onClick={() => auth.signOut()}>Sign Out</Button>) 
         : 
         (<Button onClick={signInWithGoogle} > Sign in with Google </Button>) 
       }

     </React.Fragment>
    )
   }
}

export default App;

I suggest you use store management libraries like Redux when you want to share the state between components. In this example, we have finished everything in a single component. But in realtime, you may have a complex component architecture in such use case using store management libraries may come in handy.