Build a User Management App with SvelteKit

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.

Project setup#

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#

1. Create a new project in the Supabase Dashboard.
2. Enter your project details.
3. 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.

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.

1. Go to the API Settings page in the Dashboard.
2. Find your Project URL, anon, and service_role keys on this page.

Building the App#

Let's start building the Svelte app from scratch.

Initialize a Svelte app#

We can use the SvelteKit Skeleton Project to initialize an app called supabase-sveltekit (for this tutorial we will be using TypeScript):

Then install the Supabase client library: supabase-js

And finally we want to save the environment variables in a .env. All we need are the SUPABASE_URL and the SUPABASE_KEY key that you copied earlier.

Optionally, add src/styles.css with the CSS from the example.

Supabase Auth Helpers#

SvelteKit is a highly versatile framework offering pre-rendering at build time (SSG), server-side rendering at request time (SSR), API routes, and more.

It can be challenging to authenticate your users in all these different environments, that's why we've created the Supabase Auth Helpers to make user management and data fetching within SvelteKit as easy as possible.

Install the auth helpers for SvelteKit:

Add the code below to your src/hooks.server.ts to initialize the client on the server:

If you are using TypeScript the compiler might complain about event.locals.supabase and event.locals.getSession, this can be fixed by updating your src/app.d.ts with the content below:

Create a new src/routes/+layout.server.ts file to handle the session on the server-side.

Start your dev server (npm run dev) in order to generate the ./$types files we are referencing in our project.

Create a new src/routes/+layout.ts file to handle the session and the supabase object on the client-side.

Update your src/routes/+layout.svelte:

Set up a Login page#

Supabase Auth UI#

We can use the Supabase Auth UI, a pre-built Svelte component, for authenticating users via OAuth, email, and magic links.

Install the Supabase Auth UI for Svelte

Add the Auth component to your home page

Create a src/routes/+page.server.ts file that will return our website url to be used in our redirectTo above.

Proof Key for Code Exchange (PKCE)#

As we are employing Proof Key for Code Exchange (PKCE) in our authentication flow, it is necessary to create a server endpoint responsible for exchanging the code for a session.

In the following code snippet, we perform the following steps:

• Retrieve the code sent back from the Supabase Auth server using the code query parameter.
• Exchange this code for a session, which we store in our chosen storage mechanism (in this case, cookies).
• Finally, we redirect the user to the account page.

Account page#

After a user is signed in, they need to be able to edit their profile details and manage their account. Create a new src/routes/account/+page.svelte file with the content below.

Now create the associated src/routes/account/+page.server.ts file that will handle loading our data from the server through the load function and handle all our form actions through the actions object.

Launch!#

Now that we have all the pages in place, run this in a terminal window:

And then open the browser to localhost:5173 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.

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 called Avatar.svelte in the src/routes/account directory:

Add the new widget#

And then we can add the widget to the Account page:

Storage management#

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:

Next, add a trigger that removes any obsolete avatar whenever the profile is updated or deleted:

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.

At this stage you have a fully functional application!