Writing an Authentication Trigger with Cloud Functions for Firebase - Firecasts Video Lecture | Beast Android Development: Firebase Necessities - App Development

Hey how's it going everyone I'm Jen
person and on today's fire cast I'm
going to use cloud functions for
firebase to respond to authentication
events in my last fire cast I talked
about a photo sharing app where users
upload images that then appear in a grid
I want to keep track of who is using the
app and control access to storage in the
database so I'll use firebase
authentication users will have their own
profiles which contain their email and
profile picture I want to create a
profile whenever a new user is
authenticated it will contain the users
email and profile photo that way when
the user uploads an image it will be
posted with their profile information
even if I have yet to customize their
profile certainly this work can be
handled in the client but cloud
functions enabled me to offload this
work meaning less processing power less
battery usage and less data usage
client-side plus I won't have to
duplicate the same process for my code
in iOS Android and web I can use cloud
functions to create this default profile
by triggering events when a new user is
created I'll write a function that's
triggered on creation of a new user and
then use the admin SDK to populate the
users profile in the database I'll also
create a function that's triggered on
deletion of the user which marks the
user's profile as the LEAs I do this
using two functions provided as part of
the cloud functions library functions
auth dot user on create and functions
user on delete as the name suggests on
create is triggered when a user is
created which can happen in the client
upon creating a new account adding from
the firebase console or importing from
the command-line on delete is triggered
when a user is removed which again can
be done from the client the firebase
console or the command line I'll then
use the admin SDK to write the data to
the database the admin SDK provides
unrestricted access to the database if
you'd like to know more about the admin
SDK then check out the documentation
link below alright
let's dive in as always I start by
requiring the firebase functions module
I'll also require the firebase admin
module because I will need this to
access the database to write the users
default profile
also initialize the admin SDK in the
usual way
I'll create a reference to the root of
the database now I'll export a function
called create user account it will use
the function stop dot user method which
registers a cloud function to handle
user authentication events I'll call the
on create method on functions das user
the on create method receives an event
object that describes the new user that
was added when a new user is
authenticated a user record object is
created a user record represents one
authenticated user it contains multiple
properties including display name which
is a string or null email a nullable
string photo URL a string or null and u
ID a string I can access the list of
user attributes contained in the user
record object through event dot data
here's how I make that happen I'll
access the user's UID and email to add
their default profile in the database
not all users will have an email to add
to their default new user profile for
example users who sign up with Twitter
are not required to provide an email in
that case email will be null and the key
value pair will not be added to the
database
I'll get the users photo from the user
records photo URL property I'll use a
null coalescing operator here since
photo URL may be null
but I still want the user to have a
profile picture if photo URL is null
then I'll use this default image here so
I have constants to hold the user's UID
email and profile photo now I'll use
those values to add the users profile to
the database for that I'll need to use
the admin SDK I'll create a new
reference to a path in the database
using the users view ID as the key here
we go I'll create my database reference
to the path users slash UID then I'll
set the new users profile image and
email in the database and there you have
it time to see this function in action
I'll run firebase deploy I'll head over
to the firebase console enable email and
password authentication and then add a
new user I'll be super creative with my
test email now I'll select the database
see my news or profile entry there they
are I can see the users UID and children
containing the email and photo URL I'll
click on the photo URL and you can see
the default image since my user record
object didn't have one associated with
it now we have a way of bootstrapping a
space in a database for new users but
what about when a user account is
deleted it turns out that cloud
functions also provide a way to trigger
on deletion of the user so what might we
want to do in response to this trigger I
can clean up all the users data from the
database to save space I can also just
mark the users delete it with a flag in
my app I don't want to lose any data
just yet so I'll take the second option
that way if the user decides to return
their profile still configured so now
I'll write a function that is triggered
when a user is removed it will add a
boolean flag to the users profile
indicating that they have been deleted
I'll define and export a function called
clean up user data that's triggered when
a user is deleted the event contains a
user record object just like in the
oncreate function
I'll get the users UID from the event
object's data I'll then define a
reference to the users entry in the
database using the UID and the admin SDK
finally I'll update the reference with
the boolean is deleted set to true let's
try out this clean up user data function
I'll deploy my function once again then
head over to the firebase console and
remove the user I just added I'll select
the database and you can see that the
boolean flag has been added come back
soon test user so now I have two
functions triggered by authentication
events one for when users are added and
one for when they are deleted but
there's lots more you can do with cloud
functions for more examples of ways to
use cloud functions check out the
samples on github you can find a link
below
and subscribe to the firebase YouTube
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casts and other videos about firebase
thanks for watching and I'll see you
next time in a future fire cast
you
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