Quickstart: Svelte

Intro#

This example provides the steps to build a basic user management app. It includes:

• Supabase Database: a Postgres database for storing your user data.
• Supabase Auth: users can sign in with magic links (no passwords, only email).
• Supabase Storage: users can upload a photo.
• Row Level Security: data is protected so that individuals can only access their own data.
• Instant APIs: APIs will be automatically generated when you create your database tables.

By the end of this guide you'll have an app which allows users to login and update some basic profile details:

GitHub#

Should you get stuck while working through the guide, refer to this repo.

Project set up#

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#

1. Go to app.supabase.com.
2. Click on "New Project".
3. Enter your project details.
4. 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 URL and anon key from the API settings.

1. Go to the Settings page in the Dashboard.
2. Click API in the sidebar.
3. Find your API 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:

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 anon key that you copied earlier.

.env
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.

src/supabaseClient.ts
1import { createClient } from '@supabase/supabase-js'
2
3const supabaseUrl = import.meta.env.VITE_SUPABASE_URL
4const supabaseAnonKey = import.meta.env.VITE_SUPABASE_ANON_KEY
5
6export const supabase = createClient(supabaseUrl, supabaseAnonKey)

And one 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.

src/lib/Auth.svelte
1<script lang="ts">
2  import { supabase } from 'src/supabaseClient'
3
4  let loading = false
5  let email = ''
6
7  const handleLogin = async () => {
8    try {
9      loading = true
10      const { error } = await supabase.auth.signInWithOtp({ email })
11      if (error) throw error
12      alert('Check your email for login link!')
13    } catch (error) {
14      if (error instanceof Error) {
15        alert(error.message)
16      }
17    } finally {
18      loading = false
19    }
20  }
21</script>
22
23<div class="row flex-center flex">
24  <div class="col-6 form-widget" aria-live="polite">
25    <h1 class="header">Supabase + Svelte</h1>
26    <p class="description">Sign in via magic link with your email below</p>
27    <form class="form-widget" on:submit|preventDefault="{handleLogin}">
28      <div>
29        <label for="email">Email</label>
30        <input
31          id="email"
32          class="inputField"
33          type="email"
34          placeholder="Your email"
35          bind:value="{email}"
36        />
37      </div>
38      <div>
39        <button type="submit" class="button block" aria-live="polite" disabled="{loading}">
40          <span>{loading ? 'Loading' : 'Send magic link'}</span>
41        </button>
42      </div>
43    </form>
44  </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
1<script lang="ts">
2  import { onMount } from "svelte";
3  import type { AuthSession } from "@supabase/supabase-js";
4  import { supabase } from "../supabaseClient";
5
6  export let session: AuthSession;
7
8  let loading = false
9  let username: string | null = null
10  let website: string | null = null
11  let avatarUrl: string | null = null
12
13  onMount(() => {
14    getProfile()
15  })
16
17  const getProfile = async () => {
18    try {
19      loading = true
20      const { user } = session
21
22      const { data, error, status } = await supabase
23        .from('profiles')
24        .select('username, website, avatar_url')
25        .eq('id', user.id)
26        .single()
27
28      if (error && status !== 406) throw error
29
30      if (data) {
31        username = data.username
32        website = data.website
33        avatarUrl = data.avatar_url
34      }
35    } catch (error) {
36      if (error instanceof Error) {
37        alert(error.message)
38      }
39    } finally {
40      loading = false
41    }
42  }
43
44  const updateProfile = async () => {
45    try {
46      loading = true
47      const { user } = session
48
49      const updates = {
50        id: user.id,
51        username,
52        website,
53        avatar_url: avatarUrl,
54        updated_at: new Date().toISOString(),
55      }
56
57      let { error } = await supabase.from('profiles').upsert(updates)
58
59      if (error) {
60        throw error
61      }
62    } catch (error) {
63      if (error instanceof Error) {
64        alert(error.message)
65      }
66    } finally {
67      loading = false
68    }
69  }
70</script>
71
72<form on:submit|preventDefault={updateProfile} class="form-widget">
73  <div>Email: {session.user.email}</div>
74  <div>
75    <label for="username">Name</label>
76    <input id="username" type="text" bind:value={username} />
77  </div>
78  <div>
79    <label for="website">Website</label>
80    <input id="website" type="text" bind:value={website} />
81  </div>
82  <div>
83    <button type="submit" class="button primary block" disabled={loading}>
84      {loading ? 'Saving ...' : 'Update profile'}
85    </button>
86  </div>
87  <button type="button" class="button block" on:click={() => supabase.auth.signOut()}>
88    Sign Out
89  </button>
90</form>

Launch!#

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

src/App.svelte
1<script lang="ts">
2  import { onMount } from 'svelte'
3  import { supabase } from './supabaseClient'
4  import type { AuthSession } from '@supabase/supabase-js'
5  import Account from './lib/Account.svelte'
6  import Auth from './lib/Auth.svelte'
7
8  let session: AuthSession
9
10  onMount(() => {
11    supabase.auth.getSession().then(({ data }) => {
12      session = data.session
13    })
14
15    supabase.auth.onAuthStateChange((_event, _session) => {
16      session = _session
17    })
18  })
19</script>
20
21<div class="container" style="padding: 50px 0 100px 0">
22  {#if !session}
23  <Auth />
24  {:else}
25  <Account {session} />
26  {/if}
27</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 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:

src/lib/Avatar.svelte
1<script lang="ts">
2  import { createEventDispatcher } from 'svelte'
3  import { supabase } from '../supabaseClient'
4
5  export let size: number
6  export let url: string
7
8  let avatarUrl: string = null
9  let uploading = false
10  let files: FileList
11
12  const dispatch = createEventDispatcher()
13
14  const downloadImage = async (path: string) => {
15    try {
16      const { data, error } = await supabase.storage.from('avatars').download(path)
17
18      if (error) {
19        throw error
20      }
21
22      const url = URL.createObjectURL(data)
23      avatarUrl = url
24    } catch (error) {
25      if (error instanceof Error) {
26        console.log('Error downloading image: ', error.message)
27      }
28    }
29  }
30
31  const uploadAvatar = async () => {
32    try {
33      uploading = true
34
35      if (!files || files.length === 0) {
36        throw new Error('You must select an image to upload.')
37      }
38
39      const file = files[0]
40      const fileExt = file.name.split('.').pop()
41      const filePath = `${Math.random()}.${fileExt}`
42
43      let { error } = await supabase.storage.from('avatars').upload(filePath, file)
44
45      if (error) {
46        throw error
47      }
48
49      url = filePath
50      dispatch('upload')
51    } catch (error) {
52      if (error instanceof Error) {
53        alert(error.message)
54      }
55    } finally {
56      uploading = false
57    }
58  }
59
60  $: if (url) downloadImage(url)
61</script>
62
63<div style="width: {size}px" aria-live="polite">
64  {#if avatarUrl} <img src={avatarUrl} alt={avatarUrl ? 'Avatar' : 'No image'} class="avatar image"
65  style="height: {size}px, width: {size}px" /> {:else}
66  <div class="avatar no-image" style="height: {size}px, width: {size}px" />
67  {/if}
68  <div style="width: {size}px">
69    <label class="button primary block" for="single">
70      {uploading ? 'Uploading ...' : 'Upload avatar'}
71    </label>
72    <span style="display:none">
73      <input
74        type="file"
75        id="single"
76        accept="image/*"
77        bind:files
78        on:change="{uploadAvatar}"
79        disabled="{uploading}"
80      />
81    </span>
82  </div>
83</div>

Add the new widget#

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

src/lib/Account.svelte
1<script lang="ts">
2  // Import the new component
3  import Avatar from './Avatar.svelte'
4</script>
5
6<form on:submit|preventDefault="{updateProfile}" class="form-widget">
7  <!-- Add to body -->
8  <Avatar bind:url="{avatarUrl}" size="{150}" on:upload="{updateProfile}" />
9
10  <!-- Other form elements -->
11</form>

Next steps#

At this stage you have a fully functional application!

• Got a question? Ask here.
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