with-svelte.mdx

title	description
Build a User Management App with Svelte	Learn how to use Supabase in your Svelte App.

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

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:

npm create vite@latest supabase-svelte -- --template svelte-ts
cd supabase-svelte
npm install

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

npm 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 key that you copied earlier.

VITE_SUPABASE_URL=YOUR_SUPABASE_URL
VITE_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.

import { createClient } from '@supabase/supabase-js'

const supabaseUrl = import.meta.env.VITE_SUPABASE_URL
const supabaseAnonKey = import.meta.env.VITE_SUPABASE_ANON_KEY

export 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.

Set up a login component

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.

<script lang="ts">
  import { supabase } from '../supabaseClient'

  let loading = false
  let email = ''

  const handleLogin = async () => {
    try {
      loading = true
      const { error } = await supabase.auth.signInWithOtp({ email })
      if (error) throw error
      alert('Check your email for login link!')
    } catch (error) {
      if (error instanceof Error) {
        alert(error.message)
      }
    } finally {
      loading = false
    }
  }
</script>

<div class="row flex-center flex">
  <div class="col-6 form-widget" aria-live="polite">
    <h1 class="header">Supabase + Svelte</h1>
    <p class="description">Sign in via magic link with your email below</p>
    <form class="form-widget" on:submit|preventDefault="{handleLogin}">
      <div>
        <label for="email">Email</label>
        <input
          id="email"
          class="inputField"
          type="email"
          placeholder="Your email"
          bind:value="{email}"
        />
      </div>
      <div>
        <button type="submit" class="button block" aria-live="polite" disabled="{loading}">
          <span>{loading ? 'Loading' : 'Send magic link'}</span>
        </button>
      </div>
    </form>
  </div>
</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.

<script lang="ts">
  import { onMount } from 'svelte'
  import type { AuthSession } from '@supabase/supabase-js'
  import { supabase } from '../supabaseClient'

  export let session: AuthSession

  let loading = false
  let username: string | null = null
  let website: string | null = null
  let avatarUrl: string | null = null

  onMount(() => {
    getProfile()
  })

  const getProfile = async () => {
    try {
      loading = true
      const { user } = session

      const { data, error, status } = await supabase
        .from('profiles')
        .select('username, website, avatar_url')
        .eq('id', user.id)
        .single()

      if (error && status !== 406) throw error

      if (data) {
        username = data.username
        website = data.website
        avatarUrl = data.avatar_url
      }
    } catch (error) {
      if (error instanceof Error) {
        alert(error.message)
      }
    } finally {
      loading = false
    }
  }

  const updateProfile = async () => {
    try {
      loading = true
      const { user } = session

      const updates = {
        id: user.id,
        username,
        website,
        avatar_url: avatarUrl,
        updated_at: new Date().toISOString(),
      }

      const { error } = await supabase.from('profiles').upsert(updates)

      if (error) {
        throw error
      }
    } catch (error) {
      if (error instanceof Error) {
        alert(error.message)
      }
    } finally {
      loading = false
    }
  }
</script>

<form on:submit|preventDefault="{updateProfile}" class="form-widget">
  <div>Email: {session.user.email}</div>
  <div>
    <label for="username">Name</label>
    <input id="username" type="text" bind:value="{username}" />
  </div>
  <div>
    <label for="website">Website</label>
    <input id="website" type="text" bind:value="{website}" />
  </div>
  <div>
    <button type="submit" class="button primary block" disabled="{loading}">
      {loading ? 'Saving ...' : 'Update profile'}
    </button>
  </div>
  <button type="button" class="button block" on:click={() => supabase.auth.signOut()}> Sign Out
  </button>
</form>

Launch!

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

<script lang="ts">
  import { onMount } from 'svelte'
  import { supabase } from './supabaseClient'
  import type { AuthSession } from '@supabase/supabase-js'
  import Account from './lib/Account.svelte'
  import Auth from './lib/Auth.svelte'

  let session: AuthSession | null

  onMount(() => {
    supabase.auth.getSession().then(({ data }) => {
      session = data.session
    })

    supabase.auth.onAuthStateChange((_event, _session) => {
      session = _session
    })
  })
</script>

<div class="container" style="padding: 50px 0 100px 0">
  {#if !session}
  <Auth />
  {:else}
  <Account {session} />
  {/if}
</div>

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

npm 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/

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:

<script lang="ts">
  import { createEventDispatcher } from 'svelte'
  import { supabase } from '../supabaseClient'

  export let size: number
  export let url: string | null = null

  let avatarUrl: string | null = null
  let uploading = false
  let files: FileList

  const dispatch = createEventDispatcher()

  const downloadImage = async (path: string) => {
    try {
      const { data, error } = await supabase.storage.from('avatars').download(path)

      if (error) {
        throw error
      }

      const url = URL.createObjectURL(data)
      avatarUrl = url
    } catch (error) {
      if (error instanceof Error) {
        console.log('Error downloading image: ', error.message)
      }
    }
  }

  const uploadAvatar = async () => {
    try {
      uploading = true

      if (!files || files.length === 0) {
        throw new Error('You must select an image to upload.')
      }

      const file = files[0]
      const fileExt = file.name.split('.').pop()
      const filePath = `${Math.random()}.${fileExt}`

      const { error } = await supabase.storage.from('avatars').upload(filePath, file)

      if (error) {
        throw error
      }

      url = filePath
      dispatch('upload')
    } catch (error) {
      if (error instanceof Error) {
        alert(error.message)
      }
    } finally {
      uploading = false
    }
  }

  $: if (url) downloadImage(url)
</script>

<div style="width: {size}px" aria-live="polite">
  {#if avatarUrl} <img src={avatarUrl} alt={avatarUrl ? 'Avatar' : 'No image'} class="avatar image"
  style="height: {size}px, width: {size}px" /> {:else}
  <div class="avatar no-image" style="height: {size}px, width: {size}px" />
  {/if}
  <div style="width: {size}px">
    <label class="button primary block" for="single">
      {uploading ? 'Uploading ...' : 'Upload avatar'}
    </label>
    <span style="display:none">
      <input
        type="file"
        id="single"
        accept="image/*"
        bind:files
        on:change={uploadAvatar}
        disabled={uploading}
      />
    </span>
  </div>
</div>

Add the new widget

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

<script lang="ts">
  // Import the new component
  import Avatar from './Avatar.svelte'
</script>

<form on:submit|preventDefault="{updateProfile}" class="form-widget">
  <!-- Add to body -->
  <Avatar bind:url="{avatarUrl}" size="{150}" on:upload="{updateProfile}" />

  <!-- Other form elements -->
</form>

At this stage you have a fully functional application!