Build a User Management App with Expo
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).
- Supabase Storage - users can upload a profile photo.
If you get stuck while working through this guide, refer to the full example on GitHub.
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.
Create a project#
- Create a new project in the Supabase Dashboard.
- Enter your project details.
- Wait for the new database to launch.
Set up the database schema#
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.
- Go to the SQL Editor page in the Dashboard.
- Click User Management Starter.
- Click Run.
You can easily pull the database schema down to your local project by running the following commands:
_10supabase link_10supabase db pull
Get the API Keys#
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.
- Go to the API Settings page in the Dashboard.
- Find your Project
service_rolekeys on this page.
Building the App#
Let's start building the React Native app from scratch.
Initialize a React Native app#
We can use
expo to initialize
an app called
_10npx create-expo-app -t expo-template-blank-typescript expo-user-management_10_10cd expo-user-management
Then let's install the additional dependencies: supabase-js
_10npm install @supabase/supabase-js_10npm install react-native-elements @react-native-async-storage/async-storage react-native-url-polyfill_10npx expo install expo-secure-store
Now let's create a helper file to initialize the Supabase client.
We need the API URL and the
anon key that you copied earlier.
These variables will be exposed on the browser, and that's completely fine since we have
Row Level Security enabled on our Database.
Set up a Login component#
Let's set up a React Native component to manage logins and sign ups. Users would be able to sign in with their email and password.
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
Now that we have all the components in place, let's update
Once that's done, run this in a terminal window:
And then press the appropriate key for the environment you want to test the app in and you should see the completed app.
Bonus: Profile photos#
Every Supabase project is configured with Storage for managing large files like photos and videos.
Additional dependency installation#
You will need a file picker that works on the environment you will build the project for, we will use react-native-document-picker in this example.
_10expo install react-native-document-picker
Create an upload widget#
Let's create an avatar for the user so that they can upload a profile photo. We can start by creating a new component:
Add the new widget#
And then we can add the widget to the Account page:
Now you will need to run the prebuild command to get the application working on your chosen platform.
If you upload additional profile photos, they'll accumulate
avatars bucket because of their random names with only the latest being referenced
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
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:
_34create or replace function delete_storage_object(bucket text, object text, out status int, out content text)_34returns record_34language 'plpgsql'_34security definer_34as $$_34declare_34project_url text := '<YOURPROJECTURL>';_34service_role_key text := '<YOURSERVICEROLEKEY>'; -- full access needed_34url text := project_url||'/storage/v1/object/'||bucket||'/'||object;_34begin_34select_34into status, content_34result.status::int, result.content::text_34FROM extensions.http((_34'DELETE',_34url,_34ARRAY[extensions.http_header('authorization','Bearer '||service_role_key)],_34NULL,_34NULL)::extensions.http_request) as result;_34end;_34$$;_34_34create or replace function delete_avatar(avatar_url text, out status int, out content text)_34returns record_34language 'plpgsql'_34security definer_34as $$_34begin_34select_34into status, content_34result.status, result.content_34from public.delete_storage_object('avatars', avatar_url) as result;_34end;_34$$;
Next, add a trigger that removes any obsolete avatar whenever the profile is updated or deleted:
_32create or replace function delete_old_avatar()_32returns trigger_32language 'plpgsql'_32security definer_32as $$_32declare_32status int;_32content text;_32avatar_name text;_32begin_32if coalesce(old.avatar_url, '') <> ''_32and (tg_op = 'DELETE' or (old.avatar_url <> new.avatar_url)) then_32-- extract avatar name_32avatar_name := old.avatar_url;_32select_32into status, content_32result.status, result.content_32from public.delete_avatar(avatar_name) as result;_32if status <> 200 then_32raise warning 'Could not delete avatar: % %', status, content;_32end if;_32end if;_32if tg_op = 'DELETE' then_32return old;_32end if;_32return new;_32end;_32$$;_32_32create trigger before_profile_changes_32before update of avatar_url or delete on public.profiles_32for 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.
_14create or replace function delete_old_profile()_14returns trigger_14language 'plpgsql'_14security definer_14as $$_14begin_14delete from public.profiles where id = old.id;_14return old;_14end;_14$$;_14_14create trigger before_delete_user_14before delete on auth.users_14for each row execute function public.delete_old_profile();
At this stage you have a fully functional application!