Steps to Set up the Firebase Authentication<\/strong><\/h3>\n\n\n\nWe will provide two methods for authenticating end users: Sign-In with Google and custom user accounts created using an email and password.<\/p>\n\n\n\n
Before writing any code in your project, you need to enable Firebase authentication methods from the Firebase console. Navigate to the Authentication section in your Firebase console, then click on the Sign-in Method tab. We can see multiple sign-in methods on this tab, as shown in the screenshot below.<\/p>\n\n\n\nThis blog covers the implementation of Email\/Password login along with Google Sign-In. To activate the Email\/Password method, select the Email\/Password option under the Native providers section. Following the screenshot below, activate the option and click Save to proceed.<\/p>\n\n\n\nIn this way, you can enable the Email\/Password method. After this, to enable Google Sign-In, click on the Google option in the Additional providers section. As shown in the screenshot below, enable the switch and provide the support email address. You also need to provide the SHA1 key for Android when creating the Android application.<\/p>\n\n\n\nAfter entering all the required information, click on the save button. In this way you can enable both Email\/Password and Google Sign-In authentication methods on the Firebase console. <\/p>\n\n\n\nYou can reconfirm if both methods are enabled or not, as shown in the above screenshot. Now we are ready to call the firebase authentication methods from our project.<\/p>\n\n\n\n
Google Sign-In Functionality<\/strong><\/h3>\n\n\n\nFirst we will see Sign-In with Google functionality. To sign in with Google, we have provided a SignInwithGoogle<\/code> button on the login screen. By clicking on this button, we call the signInWithGoogleButtonClicked()<\/code> method in which we call the signInWithGoogle()<\/code> method from the auth_service.dart<\/code> file, as shown below. Create a separate file named auth_service.dart<\/code> and write all the functions related to authentication in it. <\/p>\n\n\nvoid<\/span> signInWithGoogleButtonClicked(BuildContext context) async<\/span> {\n\n final userCred = await<\/span> AuthService().signInWithGoogle();\n\n if<\/span> (userCred != null<\/span>) {\n\n Navigator.push(\n\n context,\n\n MaterialPageRoute(builder: (context<\/span>) =><\/span> const<\/span> HomeScreen()),\n\n );\n\n }\n\n}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nAs shown in the above method, we invoke the signInWithGoogle()<\/code> function from the auth_service.dart<\/code> file, as illustrated below, to obtain the UserCredential data. If the UserCredential data is not empty, the user has been successfully authenticated with Google, and we navigate the user to the home screen.<\/p>\n\n\nFuture<UserCredential?> signInWithGoogle() async<\/span> {\n\n try<\/span> {\n\n final googleUser = await<\/span> GoogleSignIn().signIn();\n\n final googleAuth = await<\/span> googleUser?.authentication;\n\n final cred = GoogleAuthProvider.credential(\n\n idToken: googleAuth?.idToken, accessToken<\/span>: googleAuth?.accessToken);\n\n return<\/span> await<\/span> FirebaseAuth.instance.signInWithCredential(cred);\n\n } catch<\/span> (e) {\n\n log(e.toString());\n\n }\n\n return<\/span> null<\/span>;\n\n}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nWe need to use the function 'FirebaseAuth.instance.signInWithCredential(cred)'<\/code> to sign in with Google Sign-In. You have to provide the GoogleAuthProvider.credential<\/code> object, which can be generated by providing the Access Token and Google authentication token. These authentication token and access token can be obtained by using GoogleSignIn().signIn()<\/code> and GoogleSignIn().signIn().authentication<\/code>, respectively.<\/p>\n\n\n\nSign Up Using Email and Password<\/strong><\/h3>\n\n\n\nTo create a custom user by using email and password, we have developed a sign-up form to collect the user’s name, email, and password. After filling out the signup form, the user needs to click on the Sign up button. On the Sign up button click, we have called the onSignupClicked()<\/code> method, in which we check the simple validations. If the validations are unsuccessful, we are showing a specific text message to the employee; otherwise, we invoke the AuthService().createUserWithEmailAndPassword()<\/code> method from the auth_service.dart<\/code> file. This function will return the User model if the user is created successfully on Firebase.<\/p>\n\n\nvoid<\/span> signupButtonClicked(BuildContext context) async<\/span> {\n\n String<\/span> email = emailController.text.toString().trim();\n\n String<\/span> password = passwordController.text.toString().trim();\n\n if<\/span> (performValidation(context, email, password)) {\n\n final user = await<\/span> AuthService()\n\n .createUserWithEmailAndPassword(context, email, password);\n\n if<\/span> (user != null<\/span>) {\n\n Navigator.pop(context);\n\n CommonUtils.showToast(context, \"User created successfully.\"<\/span>);\n\n }\n\n }\n\n}\n\nbool performValidation(BuildContext context, String<\/span> email, String<\/span> password) {\n\n if<\/span> (email.isEmpty) {\n\n CommonUtils.showToast(context, \"Please enter email address.\"<\/span>);\n\n return<\/span> false<\/span>;\n\n } else<\/span> if<\/span> (password.isEmpty) {\n\n CommonUtils.showToast(context, \"Please enter password.\"<\/span>);\n\n return<\/span> false<\/span>;\n\n }\n\n return<\/span> true<\/span>;\n\n}\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nImplement a function named createUserWithEmailAndPassword()<\/code> to facilitate the registration of new users.<\/p>\n\n\nFuture<User?> createUserWithEmailAndPassword(\n\n BuildContext context, String<\/span> emailAddress, String<\/span> password) async<\/span> {\n\n try<\/span> {\n\n final credential =\n\n await<\/span> FirebaseAuth.instance.createUserWithEmailAndPassword(\n\n email: emailAddress,\n\n password<\/span>: password,\n\n );\n\n return<\/span> credential.user;\n\n } on FirebaseAuthException catch<\/span> (e) {\n\n if<\/span> (e.code == 'weak-password'<\/span>) {\n\n CommonUtils.showToast(context, 'The password provided is too weak.'<\/span>);\n\n } else<\/span> if<\/span> (e.code == 'email-already-in-use'<\/span>) {\n\n CommonUtils.showToast(\n\n context, 'The account already exists for this email.'<\/span>);\n\n }\n\n } catch<\/span> (e) {\n\n print(e);\n\n }\n\n return<\/span> null<\/span>;\n\n}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nThe FirebaseAuth.instance.createUserWithEmailAndPassword(<\/code>) method is utilized to register a new user using the given email and password. This will create a new user with the provided email and password. Firebase may throw exceptions like 'weak-password'<\/code>,
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