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 - allow users to sign up and log in.
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.

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


_53// src/hooks.server.ts
_53import { PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY } from '$env/static/public'
_53import { createServerClient } from '@supabase/ssr'
_53import type { Handle } from '@sveltejs/kit'
_53
_53export const handle: Handle = async ({ event, resolve }) => {
_53  event.locals.supabase = createServerClient(PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY, {
_53    cookies: {
_53      getAll: () => event.cookies.getAll(),
_53      /**
_53       * SvelteKit's cookies API requires `path` to be explicitly set in
_53       * the cookie options. Setting `path` to `/` replicates previous/
_53       * standard behavior.
_53       */
_53      setAll: (cookiesToSet) => {
_53        cookiesToSet.forEach(({ name, value, options }) => {
_53          event.cookies.set(name, value, { ...options, path: '/' })
_53        })
_53      },
_53    },
_53  })
_53
_53  /**
_53   * Unlike `supabase.auth.getSession()`, which returns the session _without_
_53   * validating the JWT, this function also calls `getUser()` to validate the
_53   * JWT before returning the session.
_53   */
_53  event.locals.safeGetSession = async () => {
_53    const {
_53      data: { session },
_53    } = await event.locals.supabase.auth.getSession()
_53    if (!session) {
_53      return { session: null, user: null }
_53    }
_53
_53    const {
_53      data: { user },
_53      error,
_53    } = await event.locals.supabase.auth.getUser()
_53    if (error) {
_53      // JWT validation has failed
_53      return { session: null, user: null }
_53    }
_53
_53    return { session, user }
_53  }
_53
_53  return resolve(event, {
_53    filterSerializedResponseHeaders(name) {
_53      return name === 'content-range' || name === 'x-supabase-api-version'
_53    },
_53  })
_53}

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


_12// src/routes/+layout.server.ts
_12import type { LayoutServerLoad } from './$types'
_12
_12export const load: LayoutServerLoad = async ({ locals: { safeGetSession }, cookies }) => {
_12  const { session, user } = await safeGetSession()
_12
_12  return {
_12    session,
_12    user,
_12    cookies: cookies.getAll(),
_12  }
_12}

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


_36// src/routes/+layout.ts
_36import { createBrowserClient, createServerClient, isBrowser } from '@supabase/ssr'
_36import { PUBLIC_SUPABASE_ANON_KEY, PUBLIC_SUPABASE_URL } from '$env/static/public'
_36import type { LayoutLoad } from './$types'
_36
_36export const load: LayoutLoad = async ({ fetch, data, depends }) => {
_36  depends('supabase:auth')
_36
_36  const supabase = isBrowser()
_36    ? createBrowserClient(PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY, {
_36        global: {
_36          fetch,
_36        },
_36      })
_36    : createServerClient(PUBLIC_SUPABASE_URL, PUBLIC_SUPABASE_ANON_KEY, {
_36        global: {
_36          fetch,
_36        },
_36        cookies: {
_36          getAll() {
_36            return data.cookies
_36          },
_36        },
_36      })
_36
_36  /**
_36   * It's fine to use `getSession` here, because on the client, `getSession` is
_36   * safe, and on the server, it reads `session` from the `LayoutData`, which
_36   * safely checked the session using `safeGetSession`.
_36   */
_36  const {
_36    data: { session },
_36  } = await supabase.auth.getSession()
_36
_36  return { supabase, session }
_36}

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, newSession) => {
_29			if (newSession?.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>

Create a magic link login/signup page for your application:

src/routes/+page.svelte


_54<!-- src/routes/+page.svelte -->
_54<script lang="ts">
_54	import { enhance } from '$app/forms'
_54	import type { ActionData, SubmitFunction } from './$types.js'
_54
_54	export let form: ActionData;
_54
_54	let loading = false
_54
_54	const handleSubmit: SubmitFunction = () => {
_54		loading = true
_54		return async ({ update }) => {
_54			update()
_54			loading = false
_54		}
_54	}
_54</script>
_54
_54<svelte:head>
_54	<title>User Management</title>
_54</svelte:head>
_54
_54<form class="row flex flex-center" method="POST" use:enhance={handleSubmit}>
_54	<div class="col-6 form-widget">
_54		<h1 class="header">Supabase + SvelteKit</h1>
_54		<p class="description">Sign in via magic link with your email below</p>
_54		{#if form?.message !== undefined}
_54		<div class="success {form?.success ? '' : 'fail'}">
_54			{form?.message}
_54		</div>
_54		{/if}
_54		<div>
_54			<label for="email">Email address</label>
_54			<input
_54				id="email"
_54				name="email"
_54				class="inputField"
_54				type="email"
_54				placeholder="Your email"
_54				value={form?.email ?? ''}
_54			/>
_54		</div>
_54		{#if form?.errors?.email}
_54		<span class="flex items-center text-sm error">
_54			{form?.errors?.email}
_54		</span>
_54		{/if}
_54		<div>
_54			<button class="button primary block">
_54				{ loading ? 'Loading' : 'Send magic link' }
_54			</button>
_54		</div>
_54	</div>
_54</form>

Create a src/routes/+page.server.ts file that will handle our magic link form when submitted.

src/routes/+page.server.ts


_46// src/routes/+page.server.ts
_46import { fail, redirect } from '@sveltejs/kit'
_46import type { Actions, PageServerLoad } from './$types'
_46
_46export const load: PageServerLoad = async ({ url, locals: { safeGetSession } }) => {
_46  const { session } = await safeGetSession()
_46
_46  // if the user is already logged in return them to the account page
_46  if (session) {
_46    redirect(303, '/account')
_46  }
_46
_46  return { url: url.origin }
_46}
_46
_46export const actions: Actions = {
_46  default: async (event) => {
_46    const {
_46      url,
_46      request,
_46      locals: { supabase },
_46    } = event
_46    const formData = await request.formData()
_46    const email = formData.get('email') as string
_46    const validEmail = /^[\w-\.+]+@([\w-]+\.)+[\w-]{2,8}$/.test(email)
_46
_46    if (!validEmail) {
_46      return fail(400, { errors: { email: 'Please enter a valid email address' }, email })
_46    }
_46
_46    const { error } = await supabase.auth.signInWithOtp({ email })
_46
_46    if (error) {
_46      return fail(400, {
_46        success: false,
_46        email,
_46        message: `There was an issue, Please contact support.`,
_46      })
_46    }
_46
_46    return {
_46      success: true,
_46      message: 'Please check your email for a magic link to log into the website.',
_46    }
_46  },
_46}

Email template

Change the email template to support a server-side authentication flow.

Before we proceed, let's change the email template to support sending a token hash:

Go to the Auth templates page in your dashboard.
Select Confirm signup template.
Change {{ .ConfirmationURL }} to {{ .SiteURL }}/auth/confirm?token_hash={{ .TokenHash }}&type=email.
Repeat the previous step for Magic link template.

Did you know? You could also customize emails sent out to new users, including the email's looks, content, and query parameters. Check out the settings of your project.

Confirmation endpoint

As we are working in a server-side rendering (SSR) environment, it is necessary to create a server endpoint responsible for exchanging the token_hash for a session.

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

Retrieve the token_hash sent back from the Supabase Auth server using the token_hash query parameter.
Exchange this token_hash for a session, which we store in storage (in this case, cookies).
Finally, the user is redirected to the account page or the error page.

src/routes/auth/confirm/+server.ts


_32// src/routes/auth/confirm/+server.ts
_32import type { EmailOtpType } from '@supabase/supabase-js'
_32import { redirect } from '@sveltejs/kit'
_32
_32import type { RequestHandler } from './$types'
_32
_32export const GET: RequestHandler = async ({ url, locals: { supabase } }) => {
_32  const token_hash = url.searchParams.get('token_hash')
_32  const type = url.searchParams.get('type') as EmailOtpType | null
_32  const next = url.searchParams.get('next') ?? '/account'
_32
_32  /**
_32   * Clean up the redirect URL by deleting the Auth flow parameters.
_32   *
_32   * `next` is preserved for now, because it's needed in the error case.
_32   */
_32  const redirectTo = new URL(url)
_32  redirectTo.pathname = next
_32  redirectTo.searchParams.delete('token_hash')
_32  redirectTo.searchParams.delete('type')
_32
_32  if (token_hash && type) {
_32    const { error } = await supabase.auth.verifyOtp({ type, token_hash })
_32    if (!error) {
_32      redirectTo.searchParams.delete('next')
_32      redirect(303, redirectTo)
_32    }
_32  }
_32
_32  redirectTo.pathname = '/auth/error'
_32  redirect(303, redirectTo)
_32}

Authentication error page

If there is an error with confirming the token you will be redirect to this error page.

src/routes/auth/error/+page.svelte


_10<p>Login error</p>

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    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      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!

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

Email template

Confirmation endpoint

Authentication error page

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#

Email template#

Confirmation endpoint#

Authentication error page#

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

Email template

Confirmation endpoint

Authentication error page

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget