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Quickstart: SvelteKit

Intro

This example provides the steps to build a simple user management app (from scratch!) using Supabase and Svelte. 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:

Supabase User Management example

Github

Whenever you get stuck at any point, take a look at 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 project 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.

1. Go to the "Home" section.
2. Click "SQL Editor" in the sidebar.
3. Click "User Management Starter".
4. Click "Run".

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 "Home" section.
2. Click "API" in the sidebar.
3. Click the "Authentication" heading under "API Docs".
4. Find your "SUPABASE_KEY" and "SUPABASE_URL" keys on this page (right hand side as you scroll down).

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:

npm init svelte@next supabase-sveltekit
cd supabase-sveltekit

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 SUPABASE_URL and the SUPABASE_KEY key that you copied earlier.

.env
VITE_SUPABASE_URL=YOUR_SUPABASE_URL
VITE_SUPABASE_ANON_KEY=YOUR_SUPABASE_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.

lib/supabaseClient.js
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)

And one optional step is to update the CSS file public/global.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.

lib/Auth.svelte
<script>
import {supabase} from "$lib/supabaseClient"

let loading = false
let email;

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

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

User store

To access the user information in other places, we use a writable store. Create a new file called sessionStore.js

lib/sessionStore.js
import { writable } from 'svelte/store';

export const user = writable(false);

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 Profile.svelte.

lib/Profile.svelte
<script>
import { supabase } from '$lib/supabaseClient'
import { user } from '$lib/sessionStore'

let loading = true
let username = null
let website = null
let avatar_url = null

async function getProfile() {
try {
loading = true
const user = supabase.auth.user()

let { 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
avatar_url = data.avatar_url
}
} catch (error) {
alert(error.message)
} finally {
loading = false
}
}

async function updateProfile() {
try {
loading = true
const user = supabase.auth.user()

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

let { error } = await supabase.from('profiles').upsert(updates, {
returning: 'minimal', // Don't return the value after inserting
})

if (error) throw error
} catch (error) {
alert(error.message)
} finally {
loading = false
}
}

async function signOut() {
try {
loading = true
let { error } = await supabase.auth.signOut()
if (error) throw error
} catch (error) {
alert(error.message)
} finally {
loading = false
}

}
</script>

<form use:getProfile class="form-widget" on:submit|preventDefault={updateProfile}>
<div>
<label for="email">Email</label>
<input id="email" type="text" value={$user.email} disabled />
</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="website"
bind:value={website}
/>
</div>

<div>
<input type="submit" class="button block primary" value={loading ? 'Loading ...' : 'Update'} disabled={loading}/>
</div>

<div>
<button class="button block" on:click={signOut} disabled={loading}>
Sign Out
</button>
</div>
</form>

Launch!

Now that we have all the components in place, let's update src/routes/index.svelte:

src/routes/index.svelte
<script>
import {user} from "$lib/sessionStore"
import {supabase} from "$lib/supabaseClient"
import Auth from "$lib/Auth.svelte"
import Profile from "$lib/Profile.svelte"

user.set(supabase.auth.user())

supabase.auth.onAuthStateChange((_, session) => {
user.set(session.user)
})
</script>

<div class="container" style="padding: 50px 0 100px 0;">
{#if $user}
<Profile />
{:else}
<Auth />
{/if}
</div>

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

npm run dev

And then open the browser to localhost:3000 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.

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:

lib/Avatar.svelte
<script>
import { createEventDispatcher } from 'svelte';
import { supabase } from '$lib/supabaseClient'

export let path;
export let size = "10em"

let uploading = false
let src;
let files;

const dispatch = createEventDispatcher();

async function downloadImage() {
try {
const { data, error } = await supabase.storage.from('avatars').download(path)
if (error) throw error

src = URL.createObjectURL(data)
} catch (error) {
console.error('Error downloading image: ', error.message)
}
}

async function uploadAvatar() {
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 fileName = `${Math.random()}.${fileExt}`
const filePath = `${fileName}`

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

if (uploadError) throw uploadError

path = filePath
dispatch('upload')
} catch (error) {
alert(error.message)
} finally {
uploading = false
}
}
</script>

<div>
{#if path}
<img use:downloadImage
{src}
alt="Avatar"
class="avatar image"
style="height: {size}; width: {size};"
/>
{:else}
<div class="avatar no-image" style="height: {size}; width: {size};" />
{/if}

<div style="width: {size};">
<label class="button primary block" for="single">
{uploading ? 'Uploading ...' : 'Upload'}
</label>
<input
style="visibility: hidden; position:absolute;"
type="file"
id="single"
accept="image/*"
bind:files
on:change={uploadAvatar}
disabled={uploading}
/>
</div>
</div>

Add the new widget

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

$lib/Profile.svelte
<script>
// Import the new component
import Avatar from '$lib/Avatar.svelte'
</script>

<form use:getProfile class="form-widget" on:submit|preventDefault={updateProfile}>
<!-- Add to body -->
<Avatar bind:path={avatar_url} on:upload={updateProfile} />

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

Next steps

At this stage you have a fully functional application!