Build a User Management App with Svelte

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 Vite Svelte TypeScript Template to initialize an app called supabase-svelte:


_10npm create vite@latest supabase-svelte -- --template svelte-ts
_10cd supabase-svelte
_10npm install

Then let's install the only additional dependency: supabase-js


_10npm install @supabase/supabase-js

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

.env


_10VITE_SUPABASE_URL=YOUR_SUPABASE_URL
_10VITE_SUPABASE_ANON_KEY=YOUR_SUPABASE_ANON_KEY

Now that we have the API credentials in place, let's create a helper file to initialize the Supabase client. These variables will be exposed on the browser, and that's completely fine since we have Row Level Security enabled on our Database.

src/supabaseClient.ts


_10import { createClient } from '@supabase/supabase-js'
_10
_10const supabaseUrl = import.meta.env.VITE_SUPABASE_URL
_10const supabaseAnonKey = import.meta.env.VITE_SUPABASE_ANON_KEY
_10
_10export const supabase = createClient(supabaseUrl, supabaseAnonKey)

App styling (optional)

An optional step is to update the CSS file src/app.css to make the app look nice. You can find the full contents of this file here.

Let's set up a Svelte component to manage logins and sign ups. We'll use Magic Links, so users can sign in with their email without using passwords.

src/lib/Auth.svelte


_45<script lang="ts">
_45  import { supabase } from '../supabaseClient'
_45
_45  let loading = false
_45  let email = ''
_45
_45  const handleLogin = async () => {
_45    try {
_45      loading = true
_45      const { error } = await supabase.auth.signInWithOtp({ email })
_45      if (error) throw error
_45      alert('Check your email for login link!')
_45    } catch (error) {
_45      if (error instanceof Error) {
_45        alert(error.message)
_45      }
_45    } finally {
_45      loading = false
_45    }
_45  }
_45</script>
_45
_45<div class="row flex-center flex">
_45  <div class="col-6 form-widget" aria-live="polite">
_45    <h1 class="header">Supabase + Svelte</h1>
_45    <p class="description">Sign in via magic link with your email below</p>
_45    <form class="form-widget" on:submit|preventDefault="{handleLogin}">
_45      <div>
_45        <label for="email">Email</label>
_45        <input
_45          id="email"
_45          class="inputField"
_45          type="email"
_45          placeholder="Your email"
_45          bind:value="{email}"
_45        />
_45      </div>
_45      <div>
_45        <button type="submit" class="button block" aria-live="polite" disabled="{loading}">
_45          <span>{loading ? 'Loading' : 'Send magic link'}</span>
_45        </button>
_45      </div>
_45    </form>
_45  </div>
_45</div>

Account page

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 Account.svelte.

src/lib/Account.svelte


_90<script lang="ts">
_90  import { onMount } from 'svelte'
_90  import type { AuthSession } from '@supabase/supabase-js'
_90  import { supabase } from '../supabaseClient'
_90
_90  export let session: AuthSession
_90
_90  let loading = false
_90  let username: string | null = null
_90  let website: string | null = null
_90  let avatarUrl: string | null = null
_90
_90  onMount(() => {
_90    getProfile()
_90  })
_90
_90  const getProfile = async () => {
_90    try {
_90      loading = true
_90      const { user } = session
_90
_90      const { data, error, status } = await supabase
_90        .from('profiles')
_90        .select('username, website, avatar_url')
_90        .eq('id', user.id)
_90        .single()
_90
_90      if (error && status !== 406) throw error
_90
_90      if (data) {
_90        username = data.username
_90        website = data.website
_90        avatarUrl = data.avatar_url
_90      }
_90    } catch (error) {
_90      if (error instanceof Error) {
_90        alert(error.message)
_90      }
_90    } finally {
_90      loading = false
_90    }
_90  }
_90
_90  const updateProfile = async () => {
_90    try {
_90      loading = true
_90      const { user } = session
_90
_90      const updates = {
_90        id: user.id,
_90        username,
_90        website,
_90        avatar_url: avatarUrl,
_90        updated_at: new Date().toISOString(),
_90      }
_90
_90      const { error } = await supabase.from('profiles').upsert(updates)
_90
_90      if (error) {
_90        throw error
_90      }
_90    } catch (error) {
_90      if (error instanceof Error) {
_90        alert(error.message)
_90      }
_90    } finally {
_90      loading = false
_90    }
_90  }
_90</script>
_90
_90<form on:submit|preventDefault="{updateProfile}" class="form-widget">
_90  <div>Email: {session.user.email}</div>
_90  <div>
_90    <label for="username">Name</label>
_90    <input id="username" type="text" bind:value="{username}" />
_90  </div>
_90  <div>
_90    <label for="website">Website</label>
_90    <input id="website" type="text" bind:value="{website}" />
_90  </div>
_90  <div>
_90    <button type="submit" class="button primary block" disabled="{loading}">
_90      {loading ? 'Saving ...' : 'Update profile'}
_90    </button>
_90  </div>
_90  <button type="button" class="button block" on:click="{()" ="">
_90    supabase.auth.signOut()}> Sign Out
_90  </button>
_90</form>

Launch!

Now that we have all the components in place, let's update App.svelte:

src/App.svelte


_27<script lang="ts">
_27  import { onMount } from 'svelte'
_27  import { supabase } from './supabaseClient'
_27  import type { AuthSession } from '@supabase/supabase-js'
_27  import Account from './lib/Account.svelte'
_27  import Auth from './lib/Auth.svelte'
_27
_27  let session: AuthSession
_27
_27  onMount(() => {
_27    supabase.auth.getSession().then(({ data }) => {
_27      session = data.session
_27    })
_27
_27    supabase.auth.onAuthStateChange((_event, _session) => {
_27      session = _session
_27    })
_27  })
_27</script>
_27
_27<div class="container" style="padding: 50px 0 100px 0">
_27  {#if !session}
_27  <Auth />
_27  {:else}
_27  <Account {session} />
_27  {/if}
_27</div>

Once that's done, run this in a terminal window:


_10npm run dev

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

⚠️ WARNING: Svelte uses Vite and the default port is 5173, Supabase uses port 3000. To change the redirection port for supabase go to: Authentication > Settings and change the Site Url to http://localhost:5173/

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:

src/lib/Avatar.svelte


_83<script lang="ts">
_83  import { createEventDispatcher } from 'svelte'
_83  import { supabase } from '../supabaseClient'
_83
_83  export let size: number
_83  export let url: string
_83
_83  let avatarUrl: string = null
_83  let uploading = false
_83  let files: FileList
_83
_83  const dispatch = createEventDispatcher()
_83
_83  const downloadImage = async (path: string) => {
_83    try {
_83      const { data, error } = await supabase.storage.from('avatars').download(path)
_83
_83      if (error) {
_83        throw error
_83      }
_83
_83      const url = URL.createObjectURL(data)
_83      avatarUrl = url
_83    } catch (error) {
_83      if (error instanceof Error) {
_83        console.log('Error downloading image: ', error.message)
_83      }
_83    }
_83  }
_83
_83  const uploadAvatar = async () => {
_83    try {
_83      uploading = true
_83
_83      if (!files || files.length === 0) {
_83        throw new Error('You must select an image to upload.')
_83      }
_83
_83      const file = files[0]
_83      const fileExt = file.name.split('.').pop()
_83      const filePath = `${Math.random()}.${fileExt}`
_83
_83      const { error } = await supabase.storage.from('avatars').upload(filePath, file)
_83
_83      if (error) {
_83        throw error
_83      }
_83
_83      url = filePath
_83      dispatch('upload')
_83    } catch (error) {
_83      if (error instanceof Error) {
_83        alert(error.message)
_83      }
_83    } finally {
_83      uploading = false
_83    }
_83  }
_83
_83  $: if (url) downloadImage(url)
_83</script>
_83
_83<div style="width: {size}px" aria-live="polite">
_83  {#if avatarUrl} <img src={avatarUrl} alt={avatarUrl ? 'Avatar' : 'No image'} class="avatar image"
_83  style="height: {size}px, width: {size}px" /> {:else}
_83  <div class="avatar no-image" style="height: {size}px, width: {size}px" />
_83  {/if}
_83  <div style="width: {size}px">
_83    <label class="button primary block" for="single">
_83      {uploading ? 'Uploading ...' : 'Upload avatar'}
_83    </label>
_83    <span style="display:none">
_83      <input
_83        type="file"
_83        id="single"
_83        accept="image/*"
_83        bind:files
_83        on:change="{uploadAvatar}"
_83        disabled="{uploading}"
_83      />
_83    </span>
_83  </div>
_83</div>

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

src/lib/Account.svelte


_11<script lang="ts">
_11  // Import the new component
_11  import Avatar from './Avatar.svelte'
_11</script>
_11
_11<form on:submit|preventDefault="{updateProfile}" class="form-widget">
_11  <!-- Add to body -->
_11  <Avatar bind:url="{avatarUrl}" size="{150}" on:upload="{updateProfile}" />
_11
_11  <!-- Other form elements -->
_11</form>

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!

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Product

Data API

Development Cycle

Client Library Reference

Resources

Build a User Management App with Svelte

Project setup

Create a project

Set up the database schema

Get the API Keys

Building the app

Initialize a Svelte app

App styling (optional)

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget

Storage management

Build a User Management App with Svelte

Project setup#

Create a project#

Set up the database schema#

Get the API Keys#

Building the app#

Initialize a Svelte app#

App styling (optional)#

Set up a login component#

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

App styling (optional)

Set up a login component

Account page

Launch!

Bonus: Profile photos

Create an upload widget

Add the new widget

Storage management