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.

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.

Creating a Supabase client for SSR:

The ssr package configures Supabase to use Cookies, which is required for server-side languages and frameworks.

Install the Supabase packages:


_10npm install @supabase/ssr @supabase/supabase-js

Creating a Supabase client with the ssr package automatically configures it to use Cookies. This means your user's session is available throughout the entire SvelteKit stack - page, layout, server, hooks.

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

src/hooks.server.ts


_55// src/hooks.server.ts
_55import { PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY } from '$env/static/public'
_55import { createServerClient } from '@supabase/ssr'
_55import type { Handle } from '@sveltejs/kit'
_55
_55export const handle: Handle = async ({ event, resolve }) => {
_55  event.locals.supabase = createServerClient(PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY, {
_55    cookies: {
_55      get: (key) => event.cookies.get(key),
_55      /**
_55       * Note: You have to add the `path` variable to the
_55       * set and remove method due to sveltekit's cookie API
_55       * requiring this to be set, setting the path to `/`
_55       * will replicate previous/standard behaviour (https://kit.svelte.dev/docs/types#public-types-cookies)
_55       */
_55      set: (key, value, options) => {
_55        event.cookies.set(key, value, { ...options, path: '/' })
_55      },
_55      remove: (key, options) => {
_55        event.cookies.delete(key, { ...options, path: '/' })
_55      },
_55    },
_55  })
_55
_55  /**
_55   * Unlike `supabase.auth.getSession()`, which returns the session _without_
_55   * validating the JWT, this function also calls `getUser()` to validate the
_55   * JWT before returning the session.
_55   */
_55  event.locals.safeGetSession = async () => {
_55    const {
_55      data: { session },
_55    } = await event.locals.supabase.auth.getSession()
_55    if (!session) {
_55      return { session: null, user: null }
_55    }
_55
_55    const {
_55      data: { user },
_55      error,
_55    } = await event.locals.supabase.auth.getUser()
_55    if (error) {
_55      // JWT validation has failed
_55      return { session: null, user: null }
_55    }
_55
_55    return { session, user }
_55  }
_55
_55  return resolve(event, {
_55    filterSerializedResponseHeaders(name) {
_55      return name === 'content-range'
_55    },
_55  })
_55}

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.

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

src/app.d.ts


_18// src/app.d.ts
_18
_18import { SupabaseClient, Session } from '@supabase/supabase-js'
_18
_18declare global {
_18  namespace App {
_18    interface Locals {
_18      supabase: SupabaseClient
_18      safeGetSession(): Promise<{ session: Session | null; user: User | null }>
_18    }
_18    interface PageData {
_18      session: Session | null
_18      user: User | null
_18    }
_18    // interface Error {}
_18    // interface Platform {}
_18  }
_18}

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

src/routes/+layout.server.ts


_11// src/routes/+layout.server.ts
_11import type { LayoutServerLoad } from './$types'
_11
_11export const load = (async ({ locals: { safeGetSession } }) => {
_11  const { session, user } = await safeGetSession()
_11
_11  return {
_11    session,
_11    user,
_11  }
_11}) satisfies LayoutServerLoad

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


_35// src/routes/+layout.ts
_35import { PUBLIC_SUPABASE_ANON_KEY, PUBLIC_SUPABASE_URL } from '$env/static/public'
_35import type { LayoutLoad } from './$types'
_35import { createBrowserClient, isBrowser, parse } from '@supabase/ssr'
_35
_35export const load = (async ({ fetch, data, depends }) => {
_35  depends('supabase:auth')
_35
_35  const supabase = createBrowserClient(PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY, {
_35    global: {
_35      fetch,
_35    },
_35    cookies: {
_35      get(key) {
_35        if (!isBrowser()) {
_35          return JSON.stringify(data.session)
_35        }
_35
_35        const cookie = parse(document.cookie)
_35        return cookie[key]
_35      },
_35    },
_35  })
_35
_35  /**
_35   * It's fine to use `getSession` here, because on the client, `getSession` is
_35   * safe, and on the server, it reads `session` from the `LayoutData`, which
_35   * safely checked the session using `safeGetSession`.
_35   */
_35  const {
_35    data: { session },
_35  } = await supabase.auth.getSession()
_35
_35  return { supabase, session }
_35}) satisfies LayoutLoad

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: { safeGetSession } }) => {
_14  const { session } = await safeGetSession()
_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.

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.


_62import { fail, redirect } from '@sveltejs/kit'
_62import type { Actions, PageServerLoad } from './$types'
_62
_62export const load: PageServerLoad = async ({ locals: { supabase, safeGetSession } }) => {
_62  const { session } = await safeGetSession()
_62
_62  if (!session) {
_62    throw redirect(303, '/')
_62  }
_62
_62  const { data: profile } = await supabase
_62    .from('profiles')
_62    .select(`username, full_name, website, avatar_url`)
_62    .eq('id', session.user.id)
_62    .single()
_62
_62  return { session, profile }
_62}
_62
_62export const actions: Actions = {
_62  update: async ({ request, locals: { supabase, safeGetSession } }) => {
_62    const formData = await request.formData()
_62    const fullName = formData.get('fullName') as string
_62    const username = formData.get('username') as string
_62    const website = formData.get('website') as string
_62    const avatarUrl = formData.get('avatarUrl') as string
_62
_62    const { session } = await safeGetSession()
_62
_62    const { error } = await supabase.from('profiles').upsert({
_62      id: session?.user.id,
_62      full_name: fullName,
_62      username,
_62      website,
_62      avatar_url: avatarUrl,
_62      updated_at: new Date(),
_62    })
_62
_62    if (error) {
_62      return fail(500, {
_62        fullName,
_62        username,
_62        website,
_62        avatarUrl,
_62      })
_62    }
_62
_62    return {
_62      fullName,
_62      username,
_62      website,
_62      avatarUrl,
_62    }
_62  },
_62  signout: async ({ locals: { supabase, safeGetSession } }) => {
_62    const { session } = await safeGetSession()
_62    if (session) {
_62      await supabase.auth.signOut()
_62      throw redirect(303, '/')
_62    }
_62  },
_62}

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>

At this stage you have a fully functional application!

Edit this page on GitHub

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

Creating a Supabase client for SSR:

Supabase Auth UI

Proof Key for Code Exchange (PKCE)

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget

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#

Creating a Supabase client for SSR:#

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#

Project setup

Create a project

Set up the database schema

Get the API Keys

Building the app

Initialize a Svelte app

Creating a Supabase client for SSR:

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