How to setup sendSignInLinkToEmail() from Firebase in react-native? - react-native

Question

Working on a react-native project using #react-native-firebase/app v6 we recently integrated signing in with a "magic link" using auth.sendSignInLinkToEmail
We couldn't find a good example on how to setup everything in react-native and had different problems like
- auth/invalid-dynamic-link-domain - The provided dynamic link domain is not configured or authorized for the current project.
- auth/unauthorized-continue-uri - Domain not whitelisted by project
Searching for information and implementing the "magic link login" I've prepared a guide on how to have this setup in react-native

Answer 1

Firebase project configuration
Open the Firebase console
Prepare firebase instance (Email Link sign-in)
open the Auth section.
On the Sign in method tab, enable the Email/Password provider. Note that email/password sign-in must be enabled to use email link sign-in.
In the same section, enable Email link (passwordless sign-in) sign-in method.
On the Authorized domains tab (just bellow)
Add any domains that will be used
For example the domain for the url from ActionCodeSettings needs to be included here
Configuring Firebase Dynamic Links
For IOS - you need to have an ios app configured - Add an app or specify the following throughout the firebase console
Bundle ID
App Store ID
Apple Developer Team ID
For Android - you just need to have an Android app configured with a package name
Enable Firebase Dynamic Links - open the Dynamic Links section
“Firebase Auth uses Firebase Dynamic Links when sending a link that is meant to be opened in a mobile application.
In order to use this feature, Dynamic Links need to be configured in the Firebase Console.”
(ios only) You can verify that your Firebase project is properly configured to use Dynamic Links in your iOS app by opening
the following URL: https://your_dynamic_links_domain/apple-app-site-association
It should show something like:
{
"applinks": {
"apps": [],
"details": [
{
"appID": "AP_ID123.com.example.app",
"paths": [
"NOT /_/", "/"
]
}
]
}
}
IOS Xcode project configuration for universal links
Open the Xcode project and go to the Info tab create a new URL type to be used for Dynamic Links.
Enter a unique value in Identifier field and set the URL scheme field to be your bundle identifier, which is the default URL scheme used by Dynamic Links.
In the Capabilities tab, enable Associated Domains and add the following to the Associated Domains list: applinks:your_dynamic_links_domain
(!) This should be only the domain - no https:// prefix
Android
Android doesn’t need additional configuration for default or custom domains.
Packages
A working react-native project setup with react-native-firebase is required, this is thoroughly covered in the library own documentation, here are the specific packages we used
Note: using the dynamicLinks package can be replaced with react-native's own Linking module and the code would be almost identical
Exact packages used:
"#react-native-firebase/app": "^6.7.1",
"#react-native-firebase/auth": "^6.7.1",
"#react-native-firebase/dynamic-links": "^6.7.1",
Sending the link to the user email
The module provides a sendSignInLinkToEmail method which accepts an email and action code configuration.
Firebase sends an email with a magic link to the provided email. Following the link has different behavior depending on the action code configuration.
The example below demonstrates how you could setup such a flow within your own application:
EmailLinkSignIn.jsx
import React, { useState } from 'react';
import { Alert, AsyncStorage, Button, TextInput, View } from 'react-native';
import auth from '#react-native-firebase/auth';
const EmailLinkSignIn = () => {
const [email, setEmail] = useState('');
return (
<View>
<TextInput value={email} onChangeText={text => setEmail(text)} />
<Button title="Send login link" onPress={() => sendSignInLink(email)} />
</View>
);
};
const BUNDLE_ID = 'com.example.ios';
const sendSignInLink = async (email) => {
const actionCodeSettings = {
handleCodeInApp: true,
// URL must be whitelisted in the Firebase Console.
url: 'https://www.example.com/magic-link',
iOS: {
bundleId: BUNDLE_ID,
},
android: {
packageName: BUNDLE_ID,
installApp: true,
minimumVersion: '12',
},
};
// Save the email for latter usage
await AsyncStorage.setItem('emailForSignIn', email);
await auth().sendSignInLinkToEmail(email, actionCodeSettings);
Alert.alert(`Login link sent to ${email}`);
/* You can also show a prompt to open the user's mailbox using 'react-native-email-link'
* await openInbox({ title: `Login link sent to ${email}`, message: 'Open my mailbox' }); */
};
export default EmailLinkSignIn;
We're setting handleCodeInApp to true since we want the link from the email to open our app and be handled there. How to configure and handle this is described in the next section.
The url parameter in this case is a fallback in case the link is opened from a desktop or another device that does not
have the app installed - they will be redirected to the provided url and it is a required parameter. It's also required to
have that url's domain whitelisted from Firebase console - Authentication -> Sign in method
You can find more details on the supported options here: ActionCodeSettings
Handling the link inside the app
Native projects needs to be configured so that the app can be launched by an universal link as described
above
You can use the built in Linking API from react-native or the dynamicLinks #react-native-firebase/dynamic-links to intercept and handle the link inside your app
EmailLinkHandler.jsx
import React, { useState, useEffect } from 'react';
import { ActivityIndicator, AsyncStorage, StyleSheet, Text, View } from 'react-native';
import auth from '#react-native-firebase/auth';
import dynamicLinks from '#react-native-firebase/dynamic-links';
const EmailLinkHandler = () => {
const { loading, error } = useEmailLinkEffect();
// Show an overlay with a loading indicator while the email link is processed
if (loading || error) {
return (
<View style={styles.container}>
{Boolean(error) && <Text>{error.message}</Text>}
{loading && <ActivityIndicator />}
</View>
);
}
// Hide otherwise. Or show some content if you are using this as a separate screen
return null;
};
const useEmailLinkEffect = () => {
const [loading, setLoading] = useState(false);
const [error, setError] = useState(null);
useEffect(() => {
const handleDynamicLink = async (link) => {
// Check and handle if the link is a email login link
if (auth().isSignInWithEmailLink(link.url)) {
setLoading(true);
try {
// use the email we saved earlier
const email = await AsyncStorage.getItem('emailForSignIn');
await auth().signInWithEmailLink(email, link.url);
/* You can now navigate to your initial authenticated screen
You can also parse the `link.url` and use the `continueurl` param to go to another screen
The `continueurl` would be the `url` passed to the action code settings */
}
catch (e) {
setError(e);
}
finally {
setLoading(false);
}
}
};
const unsubscribe = dynamicLinks().onLink(handleDynamicLink);
/* When the app is not running and is launched by a magic link the `onLink`
method won't fire, we can handle the app being launched by a magic link like this */
dynamicLinks().getInitialLink()
.then(link => link && handleDynamicLink(link));
// When the component is unmounted, remove the listener
return () => unsubscribe();
}, []);
return { error, loading };
};
const styles = StyleSheet.create({
container: {
...StyleSheet.absoluteFill,
backgroundColor: 'rgba(250,250,250,0.33)',
justifyContent: 'center',
alignItems: 'center',
},
});
const App = () => (
<View>
<EmailLinkHandler />
<AppScreens />
</View>
);
You can use the component in the root of your app as in this example
Or you can use it as a separate screen/route - in that case the user should be redirected to it after
the sendSignInLinkToEmail action
Upon successful sign-in, any onAuthStateChanged listeners will trigger with the new authentication state of the user. The result from the signInWithEmailLink can also be used to retrieve information about the user that signed in
Testing the email login link in the simulator
Have the app installed on the running simulator
Go through the flow that will send the magic link to the email
Go to your inbox and copy the link address
Open a terminal and paste the following code
xcrun simctl openurl booted {paste_the_link_here}
This will start the app if it’s not running
It will trigger the onLink hook (if you have a listener for it like above)
References
Deep Linking In React Native Using Firebase Dynamic Links
React Native Firebase - Dynamic Links
React Native Firebase - auth - signInWithEmailLink
firebase.google.com - Passing State In Email Actions
firebase.google.com - Authenticate with Firebase Using Email Link in JavaScript