This tutorial demonstrates how to build a basic user management app. The app authenticates and identifies the user, stores their profile information in the database, and allows the user to log in, update their profile details, and upload a profile photo. The app uses:
Supabase Database - a Postgres database for storing your user data and Row Level Security so data is protected and users can only access their own information.
Supabase Auth - users log in through magic links sent to their email (without having to set up passwords).
Before we start building we're going to set up our Database and API. This is as simple as starting a new Project in Supabase and then creating a "schema" inside the database.
Now we are going to set up the database schema. We can use the "User Management Starter" quickstart in the SQL Editor, or you can just copy/paste the SQL from below and run it yourself.
You can easily pull the database schema down to your local project by running the db pull command. Read the local development docs for detailed instructions.
supabase link --project-ref <project-id>
# You can get <project-id> from your project's dashboard URL: https://supabase.com/dashboard/project/<project-id>
Now that you've created some database tables, you are ready to insert data using the auto-generated API.
We just need to get the Project URL and anon key from the API settings.
Then let's install the only additional dependency: supabase-js
npm install @supabase/supabase-js
And finally we want to save the environment variables in a .env.
All we need are the API URL and the anon key that you copied earlier.
.env
VITE_SUPABASE_URL=YOUR_SUPABASE_URL
VITE_SUPABASE_ANON_KEY=YOUR_SUPABASE_ANON_KEY
Now that we have the API credentials in place, let's create a helper file to initialize the Supabase client. These variables will be exposed
on the browser, and that's completely fine since we have Row Level Security enabled on our Database.
src/supabaseClient.ts
import { createClient } from '@supabase/supabase-js'
After a user is signed in we can allow them to edit their profile details and manage their account.
Let's create a new component for that called Account.svelte.
src/lib/Account.svelte
<script lang="ts">
import { onMount } from "svelte";
import type { AuthSession } from "@supabase/supabase-js";
And then open the browser to localhost:5173 and you should see the completed app.
⚠️ WARNING: Svelte uses Vite and the default port is 5173, Supabase uses port 3000. To change the redirection port for supabase go to: Authentication > Settings and change the Site Url to localhost:5173
If you upload additional profile photos, they'll accumulate
in the avatars bucket because of their random names with only the latest being referenced
from public.profiles and the older versions getting orphaned.
To automatically remove obsolete storage objects, extend the database
triggers. Note that it is not sufficient to delete the objects from the
storage.objects table because that would orphan and leak the actual storage objects in
the S3 backend. Instead, invoke the storage API within Postgres via the http extension.
Enable the http extension for the extensions schema in the Dashboard.
Then, define the following SQL functions in the SQL Editor to delete
storage objects via the API:
create or replace function delete_storage_object(bucket text, object text, out status int, out content text)
returns record
language 'plpgsql'
security definer
as $$
declare
project_url text := '<YOURPROJECTURL>';
service_role_key text := '<YOURSERVICEROLEKEY>'; -- full access needed
url text := project_url||'/storage/v1/object/'||bucket||'/'||object;
create or replace function delete_avatar(avatar_url text, out status int, out content text)
returns record
language 'plpgsql'
security definer
as $$
begin
select
into status, content
result.status, result.content
from public.delete_storage_object('avatars', avatar_url) as result;
end;
$$;
Next, add a trigger that removes any obsolete avatar whenever the
profile is updated or deleted:
create or replace function delete_old_avatar()
returns trigger
language 'plpgsql'
security definer
as $$
declare
status int;
content text;
avatar_name text;
begin
if coalesce(old.avatar_url, '') <> ''
and (tg_op = 'DELETE' or (old.avatar_url <> coalesce(new.avatar_url, ''))) then
-- extract avatar name
avatar_name := old.avatar_url;
select
into status, content
result.status, result.content
from public.delete_avatar(avatar_name) as result;
if status <> 200 then
raise warning 'Could not delete avatar: % %', status, content;
end if;
end if;
if tg_op = 'DELETE' then
return old;
end if;
return new;
end;
$$;
create trigger before_profile_changes
before update of avatar_url or delete on public.profiles
for each row execute function public.delete_old_avatar();
Finally, delete the public.profile row before a user is deleted.
If this step is omitted, you won't be able to delete users without
first manually deleting their avatar image.
create or replace function delete_old_profile()
returns trigger
language 'plpgsql'
security definer
as $$
begin
delete from public.profiles where id = old.id;
return old;
end;
$$;
create trigger before_delete_user
before delete on auth.users
for each row execute function public.delete_old_profile();
At this stage you have a fully functional application!
