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Supabase and Svelte Quickstart Guide

Rory Wilding
Published: August 20, 2022

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 usage 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 that allows users to log in and update some basic profile details:

basic profile details

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

Go to app.supabase.com.

  1. Click on “New Project”.
  2. Enter your project details.
  3. 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.

-- Create a table for public "profiles"
create table profiles (
  id uuid references auth.users not null,
  updated_at timestamp with time zone,
  username text unique,
  avatar_url text,
  website text,
  primary key (id),
  unique(username),
  constraint username_length check (char_length(username) >= 3)
);
alter table profiles enable row level security;
create policy "Public profiles are viewable by everyone."
  on profiles for select
  using ( true );
create policy "Users can insert their own profile."
  on profiles for insert
  with check ( auth.uid() = id );
create policy "Users can update own profile."
  on profiles for update
  using ( auth.uid() = id );
-- Set up Realtime!
begin;
  drop publication if exists supabase_realtime;
  create publication supabase_realtime;
commit;
alter publication supabase_realtime add table profiles;
-- Set up Storage!
insert into storage.buckets (id, name)
values ('avatars', 'avatars');
create policy "Avatar images are publicly accessible."
  on storage.objects for select
  using ( bucket_id = 'avatars' );
create policy "Anyone can upload an avatar."
  on storage.objects for insert
  with check ( bucket_id = 'avatars' );

UI

  1. Go to the “SQL” section.
  2. Click “User Management Starter”.
  3. 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 “SQL” section.
  2. Click “User Management Starter”.
  3. Click “Run”.

Building the App

Let’s start building the Svelte app from scratch.

Initialize a Svelte App

We can use the Quickstart Svelte Template to initialize an app called supabase-svelte:

npx degit sveltejs/template supabase-svelte
cd supabase-svelte

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

npm

npm install @supabase/supabase-js

Yarn

yarn add @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
SVELTE_APP_SUPABASE_URL=YOUR_SUPABASE_URL
SVELTE_APP_SUPABASE_ANON_KEY=YOUR_SUPABASE_ANON_KEY

Our app is almost functional, to make svelte work with supabase and .env files we first need to change the rollup.config.js file a bit. Supabase imports json files, to convert .json files to ES6 modules we need the @rollup/plugin-json install it by running:

npm

npm install --save-dev @rollup/plugin-json

Yarn

yarn add --save-dev dotenv @rollup/plugin-replace

and add these plugins to the rollup.config.js file.

 rollup.config.js
import { config } from 'dotenv';
  import replace from '@rollup/plugin-replace';
  import json from '@rollup/plugin-json'
  export default {
    plugins: [
    replace({
            __api: JSON.stringify({
                env: {
                    isProd: production,
                    ...config().parsed // attached the .env config
                }
            }),
            delimiters: ['', '']
        }),
        json(),
    // ...
    ],
    // ...
  }

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.js
import { createClient } from '@supabase/supabase-js'
const supabaseUrl = __api.env.SVELTE_APP_SUPABASE_URL
const supabaseAnonKey = __api.env.SVELTE_APP_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.

” data-lang=”text/html”>

/src/Auth.svelte
<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>

Source: dzone.com