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.

Supabase User Management example

If you get stuck while working through this guide, refer to the full example on GitHub.

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

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 db pull command. Read the local development docs for detailed instructions.


_10supabase link --project-ref <project-id>
_10# You can get <project-id> from your project's dashboard URL: https://supabase.com/dashboard/project/<project-id>
_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 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):


_10npm create svelte@latest supabase-sveltekit
_10cd supabase-sveltekit
_10npm install

Then install the Supabase client library: supabase-js


_10npm install @supabase/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.

.env


_10PUBLIC_SUPABASE_URL="YOUR_SUPABASE_URL"
_10PUBLIC_SUPABASE_ANON_KEY="YOUR_SUPABASE_KEY"

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:


_10npm install @supabase/auth-helpers-sveltekit @supabase/supabase-js

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

src/hooks.server.ts


_28// src/hooks.server.ts
_28import { PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY } from '$env/static/public'
_28import { createSupabaseServerClient } from '@supabase/auth-helpers-sveltekit'
_28import type { Handle } from '@sveltejs/kit'
_28
_28export const handle: Handle = async ({ event, resolve }) => {
_28  event.locals.supabase = createSupabaseServerClient({
_28    supabaseUrl: PUBLIC_SUPABASE_URL,
_28    supabaseKey: PUBLIC_SUPABASE_ANON_KEY,
_28    event,
_28  })
_28
_28  /**
_28   * A convenience helper so we can just call await getSession() instead const { data: { session } } = await supabase.auth.getSession()
_28   */
_28  event.locals.getSession = async () => {
_28    const {
_28      data: { session },
_28    } = await event.locals.supabase.auth.getSession()
_28    return session
_28  }
_28
_28  return resolve(event, {
_28    filterSerializedResponseHeaders(name) {
_28      return name === 'content-range'
_28    },
_28  })
_28}

Note that auth.getSession reads the auth token and the unencoded session data from the local storage medium. It doesn't send a request back to the Supabase Auth server unless the local session is expired.

You should never trust the unencoded session data if you're writing server code, since it could be tampered with by the sender. If you need verified, trustworthy user data, call auth.getUser instead, which always makes a request to the Auth server to fetch trusted data.

In this case, the session information from getSession is supplied to the Supabase client so it can retrieve the auth token. This is safe, since the auth token signature will be revalidated on the Auth server. But you shouldn't trust the unsigned data that is stored alongside the JWT.

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:

src/app.d.ts


_17// src/app.d.ts
_17
_17import { SupabaseClient, Session } from '@supabase/supabase-js'
_17
_17declare global {
_17  namespace App {
_17    interface Locals {
_17      supabase: SupabaseClient
_17      getSession(): Promise<Session | null>
_17    }
_17    interface PageData {
_17      session: Session | null
_17    }
_17    // interface Error {}
_17    // interface Platform {}
_17  }
_17}

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

src/routes/+layout.server.ts


_10// src/routes/+layout.server.ts
_10export const load = async ({ locals: { getSession } }) => {
_10  return {
_10    session: await getSession(),
_10  }
_10}

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.

src/routes/+layout.ts


_20// src/routes/+layout.ts
_20import { PUBLIC_SUPABASE_ANON_KEY, PUBLIC_SUPABASE_URL } from '$env/static/public'
_20import { createSupabaseLoadClient } from '@supabase/auth-helpers-sveltekit'
_20
_20export const load = async ({ fetch, data, depends }) => {
_20  depends('supabase:auth')
_20
_20  const supabase = createSupabaseLoadClient({
_20    supabaseUrl: PUBLIC_SUPABASE_URL,
_20    supabaseKey: PUBLIC_SUPABASE_ANON_KEY,
_20    event: { fetch },
_20    serverSession: data.session,
_20  })
_20
_20  const {
_20    data: { session },
_20  } = await supabase.auth.getSession()
_20
_20  return { supabase, session }
_20}

Update your src/routes/+layout.svelte:

src/routes/+layout.svelte


_29<!-- src/routes/+layout.svelte -->
_29<script lang="ts">
_29	import '../styles.css'
_29	import { invalidate } from '$app/navigation'
_29	import { onMount } from 'svelte'
_29
_29	export let data
_29
_29	let { supabase, session } = data
_29	$: ({ supabase, session } = data)
_29
_29	onMount(() => {
_29		const { data } = supabase.auth.onAuthStateChange((event, _session) => {
_29			if (_session?.expires_at !== session?.expires_at) {
_29				invalidate('supabase:auth')
_29			}
_29		})
_29
_29		return () => data.subscription.unsubscribe()
_29	})
_29</script>
_29
_29<svelte:head>
_29	<title>User Management</title>
_29</svelte:head>
_29
_29<div class="container" style="padding: 50px 0 100px 0">
_29	<slot />
_29</div>

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


_10npm install @supabase/auth-ui-svelte @supabase/auth-ui-shared

Add the Auth component to your home page

src/routes/+page.svelte


_23<!-- src/routes/+page.svelte -->
_23<script lang="ts">
_23	import { Auth } from '@supabase/auth-ui-svelte'
_23	import { ThemeSupa } from '@supabase/auth-ui-shared'
_23
_23	export let data
_23</script>
_23
_23<svelte:head>
_23	<title>User Management</title>
_23</svelte:head>
_23
_23<div class="row flex-center flex">
_23	<div class="col-6 form-widget">
_23		<Auth
_23			supabaseClient={data.supabase}
_23			view="magic_link"
_23			redirectTo={`${data.url}/auth/callback`}
_23			showLinks={false}
_23			appearance={{ theme: ThemeSupa, style: { input: 'color: #fff' } }}
_23		/>
_23	</div>
_23</div>

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


_14// src/routes/+page.server.ts
_14import { redirect } from '@sveltejs/kit'
_14import type { PageServerLoad } from './$types'
_14
_14export const load: PageServerLoad = async ({ url, locals: { getSession } }) => {
_14  const session = await getSession()
_14
_14  // if the user is already logged in return them to the account page
_14  if (session) {
_14    throw redirect(303, '/account')
_14  }
_14
_14  return { url: url.origin }
_14}

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.


_12// src/routes/auth/callback/+server.js
_12import { redirect } from '@sveltejs/kit'
_12
_12export const GET = async ({ url, locals: { supabase } }) => {
_12  const code = url.searchParams.get('code')
_12
_12  if (code) {
_12    await supabase.auth.exchangeCodeForSession(code)
_12  }
_12
_12  throw redirect(303, '/account')
_12}

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.

src/routes/account/+page.svelte


_78<!-- src/routes/account/+page.svelte -->
_78<script lang="ts">
_78	import { enhance } from '$app/forms';
_78	import type { SubmitFunction } from '@sveltejs/kit';
_78
_78	export let data
_78	export let form
_78
_78	let { session, supabase, profile } = data
_78	$: ({ session, supabase, profile } = data)
_78
_78	let profileForm: HTMLFormElement
_78	let loading = false
_78	let fullName: string = profile?.full_name ?? ''
_78	let username: string = profile?.username ?? ''
_78	let website: string = profile?.website ?? ''
_78	let avatarUrl: string = profile?.avatar_url ?? ''
_78
_78	const handleSubmit: SubmitFunction = () => {
_78		loading = true
_78		return async () => {
_78			loading = false
_78		}
_78	}
_78
_78	const handleSignOut: SubmitFunction = () => {
_78		loading = true
_78		return async ({ update }) => {
_78			loading = false
_78			update()
_78		}
_78	}
_78</script>
_78
_78<div class="form-widget">
_78	<form
_78		class="form-widget"
_78		method="post"
_78		action="?/update"
_78		use:enhance={handleSubmit}
_78		bind:this={profileForm}
_78	>
_78		<div>
_78			<label for="email">Email</label>
_78			<input id="email" type="text" value={session.user.email} disabled />
_78		</div>
_78
_78		<div>
_78			<label for="fullName">Full Name</label>
_78			<input id="fullName" name="fullName" type="text" value={form?.fullName ?? fullName} />
_78		</div>
_78
_78		<div>
_78			<label for="username">Username</label>
_78			<input id="username" name="username" type="text" value={form?.username ?? username} />
_78		</div>
_78
_78		<div>
_78			<label for="website">Website</label>
_78			<input id="website" name="website" type="url" value={form?.website ?? website} />
_78		</div>
_78
_78		<div>
_78			<input
_78				type="submit"
_78				class="button block primary"
_78				value={loading ? 'Loading...' : 'Update'}
_78				disabled={loading}
_78			/>
_78		</div>
_78	</form>
_78
_78	<form method="post" action="?/signout" use:enhance={handleSignOut}>
_78		<div>
_78			<button class="button block" disabled={loading}>Sign Out</button>
_78		</div>
_78	</form>
_78</div>

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.


_61import { fail, redirect } from '@sveltejs/kit'
_61
_61export const load = async ({ locals: { supabase, getSession } }) => {
_61  const session = await getSession()
_61
_61  if (!session) {
_61    throw redirect(303, '/')
_61  }
_61
_61  const { data: profile } = await supabase
_61    .from('profiles')
_61    .select(`username, full_name, website, avatar_url`)
_61    .eq('id', session.user.id)
_61    .single()
_61
_61  return { session, profile }
_61}
_61
_61export const actions = {
_61  update: async ({ request, locals: { supabase, getSession } }) => {
_61    const formData = await request.formData()
_61    const fullName = formData.get('fullName') as string
_61    const username = formData.get('username') as string
_61    const website = formData.get('website') as string
_61    const avatarUrl = formData.get('avatarUrl') as string
_61
_61    const session = await getSession()
_61
_61    const { error } = await supabase.from('profiles').upsert({
_61      id: session?.user.id,
_61      full_name: fullName,
_61      username,
_61      website,
_61      avatar_url: avatarUrl,
_61      updated_at: new Date(),
_61    })
_61
_61    if (error) {
_61      return fail(500, {
_61        fullName,
_61        username,
_61        website,
_61        avatarUrl,
_61      })
_61    }
_61
_61    return {
_61      fullName,
_61      username,
_61      website,
_61      avatarUrl,
_61    }
_61  },
_61  signout: async ({ locals: { supabase, getSession } }) => {
_61    const session = await getSession()
_61    if (session) {
_61      await supabase.auth.signOut()
_61      throw redirect(303, '/')
_61    }
_61  },
_61}

Launch!

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


_10npm run dev

And then open the browser to localhost:5173 and you should see the completed app.

Supabase Svelte

Bonus: Profile photos

Every Supabase project is configured with Storage for managing large files like photos and videos.

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:

src/routes/account/Avatar.svelte


_94<!-- src/routes/account/Avatar.svelte -->
_94<script lang="ts">
_94	import type { SupabaseClient } from '@supabase/supabase-js'
_94	import { createEventDispatcher } from 'svelte'
_94
_94	export let size = 10
_94	export let url: string
_94	export let supabase: SupabaseClient
_94
_94	let avatarUrl: string | null = null
_94	let uploading = false
_94	let files: FileList
_94
_94	const dispatch = createEventDispatcher()
_94
_94	const downloadImage = async (path: string) => {
_94		try {
_94			const { data, error } = await supabase.storage.from('avatars').download(path)
_94
_94			if (error) {
_94				throw error
_94			}
_94
_94			const url = URL.createObjectURL(data)
_94			avatarUrl = url
_94		} catch (error) {
_94			if (error instanceof Error) {
_94				console.log('Error downloading image: ', error.message)
_94			}
_94		}
_94	}
_94
_94	const uploadAvatar = async () => {
_94		try {
_94			uploading = true
_94
_94			if (!files || files.length === 0) {
_94				throw new Error('You must select an image to upload.')
_94			}
_94
_94			const file = files[0]
_94			const fileExt = file.name.split('.').pop()
_94			const filePath = `${Math.random()}.${fileExt}`
_94
_94			const { error } = await supabase.storage.from('avatars').upload(filePath, file)
_94
_94			if (error) {
_94				throw error
_94			}
_94
_94			url = filePath
_94			setTimeout(() => {
_94				dispatch('upload')
_94			}, 100)
_94		} catch (error) {
_94			if (error instanceof Error) {
_94				alert(error.message)
_94			}
_94		} finally {
_94			uploading = false
_94		}
_94	}
_94
_94	$: if (url) downloadImage(url)
_94</script>
_94
_94<div>
_94	{#if avatarUrl}
_94		<img
_94			src={avatarUrl}
_94			alt={avatarUrl ? 'Avatar' : 'No image'}
_94			class="avatar image"
_94			style="height: {size}em; width: {size}em;"
_94		/>
_94	{:else}
_94		<div class="avatar no-image" style="height: {size}em; width: {size}em;" />
_94	{/if}
_94	<input type="hidden" name="avatarUrl" value={url} />
_94
_94	<div style="width: {size}em;">
_94		<label class="button primary block" for="single">
_94			{uploading ? 'Uploading ...' : 'Upload'}
_94		</label>
_94		<input
_94			style="visibility: hidden; position:absolute;"
_94			type="file"
_94			id="single"
_94			accept="image/*"
_94			bind:files
_94			on:change={uploadAvatar}
_94			disabled={uploading}
_94		/>
_94	</div>
_94</div>

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

src/routes/account/+page.svelte


_27<!-- src/routes/account/+page.svelte -->
_27<script lang="ts">
_27  // Import the new component
_27  import Avatar from './Avatar.svelte'
_27</script>
_27
_27<div class="form-widget">
_27  <form
_27    class="form-widget"
_27    method="post"
_27    action="?/update"
_27    use:enhance={handleSubmit}
_27    bind:this={profileForm}
_27  >
_27    <!-- Add to body -->
_27    <Avatar
_27        {supabase}
_27        bind:url={avatarUrl}
_27        size={10}
_27        on:upload={() => {
_27          profileForm.requestSubmit();
_27        }}
_27      />
_27
_27    <!-- Other form elements -->
_27  </form>
_27</div>

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:


_34create or replace function delete_storage_object(bucket text, object text, out status int, out content text)
_34returns record
_34language 'plpgsql'
_34security definer
_34as $$
_34declare
_34  project_url text := '<YOURPROJECTURL>';
_34  service_role_key text := '<YOURSERVICEROLEKEY>'; --  full access needed
_34  url text := project_url||'/storage/v1/object/'||bucket||'/'||object;
_34begin
_34  select
_34      into status, content
_34           result.status::int, result.content::text
_34      FROM extensions.http((
_34    'DELETE',
_34    url,
_34    ARRAY[extensions.http_header('authorization','Bearer '||service_role_key)],
_34    NULL,
_34    NULL)::extensions.http_request) as result;
_34end;
_34$$;
_34
_34create or replace function delete_avatar(avatar_url text, out status int, out content text)
_34returns record
_34language 'plpgsql'
_34security definer
_34as $$
_34begin
_34  select
_34      into status, content
_34           result.status, result.content
_34      from public.delete_storage_object('avatars', avatar_url) as result;
_34end;
_34$$;

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 $$
_32declare
_32  status int;
_32  content text;
_32  avatar_name text;
_32begin
_32  if coalesce(old.avatar_url, '') <> ''
_32      and (tg_op = 'DELETE' or (old.avatar_url <> coalesce(new.avatar_url, ''))) then
_32    -- extract avatar name
_32    avatar_name := old.avatar_url;
_32    select
_32      into status, content
_32      result.status, result.content
_32      from public.delete_avatar(avatar_name) as result;
_32    if status <> 200 then
_32      raise warning 'Could not delete avatar: % %', status, content;
_32    end if;
_32  end if;
_32  if tg_op = 'DELETE' then
_32    return old;
_32  end if;
_32  return new;
_32end;
_32$$;
_32
_32create trigger before_profile_changes
_32  before update of avatar_url or delete on public.profiles
_32  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.


_14create or replace function delete_old_profile()
_14returns trigger
_14language 'plpgsql'
_14security definer
_14as $$
_14begin
_14  delete from public.profiles where id = old.id;
_14  return old;
_14end;
_14$$;
_14
_14create trigger before_delete_user
_14  before delete on auth.users
_14  for each row execute function public.delete_old_profile();

At this stage you have a fully functional application!

Edit this page on GitHub

Product

Data API

Development Cycle

Client Library Reference

Resources

Build a User Management App with SvelteKit

Project setup

Create a project

Set up the database schema

Get the API Keys

Building the app

Initialize a Svelte app

Supabase Auth Helpers

Supabase Auth UI

Proof Key for Code Exchange (PKCE)

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget

Storage management

Build a User Management App with SvelteKit

Project setup#

Create a project#

Set up the database schema#

Get the API Keys#

Building the app#

Initialize a Svelte app#

Supabase Auth Helpers#

Set up a login page#

Supabase Auth UI#

Proof Key for Code Exchange (PKCE)#

Account page#

Launch!#

Bonus: Profile photos#

Create an upload widget#

Add the new widget#

Storage management#

Project setup

Create a project

Set up the database schema

Get the API Keys

Building the app

Initialize a Svelte app

Supabase Auth Helpers

Set up a login page

Supabase Auth UI

Proof Key for Code Exchange (PKCE)

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget

Storage management