Meteor: How to login with Email, GitHub, Twitter, Google and Facebook account and add credentials to an existing user account

When an user has already an account in the Meteor application, we don't want to create another user in MongoDB when he tries to login with other OAuth service. Rather we connect the accounts and add a new login service to the existing user's services collection.

This code doesn't work for Twitter, because Twitter does not return email in the user data. Therefore, there is no way how to to connect Twitter account by email. I propose to exclude Twitter from your application until it is solved by Meteor (requestPermissions).

Also Github can have an account without email. So when user tries to login with GitHub without email, a new account is created.

Just create a new file oauth.js in server folder and copy paste the code below.

	isProdEnv = function () {
	if (process.env.ROOT_URL == "http://localhost:3000") {
	return false;
	} else {
	return true;
	}
	}
	Accounts.loginServiceConfiguration.remove({
	service: 'google'
	});
	Accounts.loginServiceConfiguration.remove({
	service: 'facebook'
	});
	Accounts.loginServiceConfiguration.remove({
	service: 'twitter'
	});
	Accounts.loginServiceConfiguration.remove({
	service: 'github'
	});
	if (isProdEnv()) {
	Accounts.loginServiceConfiguration.insert({
	service: 'github',
	clientId: '00000',
	secret: '00000'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'twitter',
	consumerKey: '00000',
	secret: '00000'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'google',
	appId: '00000',
	secret: '00000'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'facebook',
	appId: '00000',
	secret: '00000'
	});
	} else {
	// dev environment
	Accounts.loginServiceConfiguration.insert({
	service: 'github',
	clientId: '11111',
	secret: '11111'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'twitter',
	consumerKey: '11111',
	secret: '11111'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'google',
	clientId: '11111',
	secret: '11111'
	});
	Accounts.loginServiceConfiguration.insert({
	service: 'facebook',
	appId: '11111',
	secret: '11111'
	});
	}
	Accounts.onCreateUser(function (options, user) {
	if (user.services) {
	if (options.profile) {
	user.profile = options.profile
	}
	var service = _.keys(user.services)[0];
	var email = user.services[service].email;
	if (!email) {
	if (user.emails) {
	email = user.emails.address;
	}
	}
	if (!email) {
	email = options.email;
	}
	if (!email) {
	// if email is not set, there is no way to link it with other accounts
	return user;
	}
	// see if any existing user has this email address, otherwise create new
	var existingUser = Meteor.users.findOne({'emails.address': email});
	if (!existingUser) {
	// check for email also in other services
	var existingGitHubUser = Meteor.users.findOne({'services.github.email': email});
	var existingGoogleUser = Meteor.users.findOne({'services.google.email': email});
	var existingTwitterUser = Meteor.users.findOne({'services.twitter.email': email});
	var existingFacebookUser = Meteor.users.findOne({'services.facebook.email': email});
	var doesntExist = !existingGitHubUser && !existingGoogleUser && !existingTwitterUser && !existingFacebookUser;
	if (doesntExist) {
	// return the user as it came, because there he doesn't exist in the DB yet
	return user;
	} else {
	existingUser = existingGitHubUser || existingGoogleUser || existingTwitterUser || existingFacebookUser;
	if (existingUser) {
	if (user.emails) {
	// user is signing in by email, we need to set it to the existing user
	existingUser.emails = user.emails;
	}
	}
	}
	}
	// precaution, these will exist from accounts-password if used
	if (!existingUser.services) {
	existingUser.services = { resume: { loginTokens: [] }};
	}
	// copy accross new service info
	existingUser.services[service] = user.services[service];
	existingUser.services.resume.loginTokens.push(
	user.services.resume.loginTokens[0]
	);
	// even worse hackery
	Meteor.users.remove({_id: existingUser._id}); // remove existing record
	return existingUser; // record is re-inserted
	}
	});

view raw oauth.js hosted with ❤ by GitHub

Thanks to Gadi Cohen post.

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