SeverLess programming with React + Supabase - 1

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:

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.

1. Go to the SQL Editor page in the Dashboard.
2. Click User Management Starter.
3. Click Run.

SQL

-- Create a table for public profiles
create table profiles (
  id uuid references auth.users not null primary key,
  updated_at timestamp with time zone,
  username text unique,
  full_name text,
  avatar_url text,
  website text,

  constraint username_length check (char_length(username) >= 3)
);
-- Set up Row Level Security (RLS)
-- See https://supabase.com/docs/guides/auth/row-level-security for more details.
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);

-- This trigger automatically creates a profile entry when a new user signs up via Supabase Auth.
-- See https://supabase.com/docs/guides/auth/managing-user-data#using-triggers for more details.
create function public.handle_new_user()
returns trigger as $$
begin
  insert into public.profiles (id, full_name, avatar_url)
  values (new.id, new.raw_user_meta_data->>'full_name', new.raw_user_meta_data->>'avatar_url');
  return new;
end;
$$ language plpgsql security definer;
create trigger on_auth_user_created
  after insert on auth.users
  for each row execute procedure public.handle_new_user();

-- Set up Storage!
insert into storage.buckets (id, name)
  values ('avatars', 'avatars');

-- Set up access controls for storage.
-- See https://supabase.com/docs/guides/storage#policy-examples for more details.
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');

create policy "Anyone can update their own avatar." on storage.objects
  for update using (auth.uid() = owner) with check (bucket_id = 'avatars');

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 React app from scratch.

Initialize a React app

We can use Create React App to initialize an app called supabase-react:

npx create-react-app supabase-react
cd supabase-react

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


REACT_APP_SUPABASE_URL=YOUR_SUPABASE_URL
REACT_APP_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.js


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

const supabaseUrl = process.env.REACT_APP_SUPABASE_URL
const supabaseAnonKey = process.env.REACT_APP_SUPABASE_ANON_KEY

export const supabase = createClient(supabaseUrl, supabaseAnonKey)

And one optional step is to update the CSS file src/index.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 React component to manage logins and sign ups. We'll use Magic Links, so users can sign in with their email without using passwords.

src/Auth.js


import { useState } from 'react'
import { supabase } from './supabaseClient'

export default function Auth() {
  const [loading, setLoading] = useState(false)
  const [email, setEmail] = useState('')

  const handleLogin = async (e) => {
    e.preventDefault()

    try {
      setLoading(true)
      const { error } = await supabase.auth.signInWithOtp({ email })
      if (error) throw error
      alert('Check your email for the login link!')
    } catch (error) {
      alert(error.error_description || error.message)
    } finally {
      setLoading(false)
    }
  }

  return (
    <div className="row flex-center flex">
      <div className="col-6 form-widget" aria-live="polite">
        <h1 className="header">Supabase + React</h1>
        <p className="description">Sign in via magic link with your email below</p>
        {loading ? (
          'Sending magic link...'
        ) : (
          <form onSubmit={handleLogin}>
            <label htmlFor="email">Email</label>
            <input
              id="email"
              className="inputField"
              type="email"
              placeholder="Your email"
              value={email}
              onChange={(e) => setEmail(e.target.value)}
            />
            <button className="button block" aria-live="polite">
              Send magic link
            </button>
          </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.js.

src/Account.js


import { useState, useEffect } from 'react'
import { supabase } from './supabaseClient'

const Account = ({ session }) => {
  const [loading, setLoading] = useState(true)
  const [username, setUsername] = useState(null)
  const [website, setWebsite] = useState(null)
  const [avatar_url, setAvatarUrl] = useState(null)

  useEffect(() => {
    getProfile()
  }, [session])

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

      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) {
        setUsername(data.username)
        setWebsite(data.website)
        setAvatarUrl(data.avatar_url)
      }
    } catch (error) {
      alert(error.message)
    } finally {
      setLoading(false)
    }
  }

  const updateProfile = async (e) => {
    e.preventDefault()

    try {
      setLoading(true)
      const { user } = session

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

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

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

  return (
    <div aria-live="polite">
      {loading ? (
        'Saving ...'
      ) : (
        <form onSubmit={updateProfile} className="form-widget">
          <div>Email: {session.user.email}</div>
          <div>
            <label htmlFor="username">Name</label>
            <input
              id="username"
              type="text"
              value={username || ''}
              onChange={(e) => setUsername(e.target.value)}
            />
          </div>
          <div>
            <label htmlFor="website">Website</label>
            <input
              id="website"
              type="url"
              value={website || ''}
              onChange={(e) => setWebsite(e.target.value)}
            />
          </div>
          <div>
            <button className="button primary block" disabled={loading}>
              Update profile
            </button>
          </div>
        </form>
      )}
      <button type="button" className="button block" onClick={() => supabase.auth.signOut()}>
        Sign Out
      </button>
    </div>
  )
}

export default Account

Launch!

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

src/App.js


import './index.css'
import { useState, useEffect } from 'react'
import { supabase } from './supabaseClient'
import Auth from './Auth'
import Account from './Account'

export default function App() {
  const [session, setSession] = useState(null)

  useEffect(() => {
    supabase.auth.getSession().then(({ data: { session } }) => {
      setSession(session)
    })

    supabase.auth.onAuthStateChange((_event, session) => {
      setSession(session)
    })
  }, [])

  return (
    <div className="container" style={{ padding: '50px 0 100px 0' }}>
      {!session ? <Auth /> : <Account key={session.user.id} session={session} />}
    </div>
  )
}

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

npm start

And then open the browser to localhost:3000 and you should see the completed app.

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/Avatar.js


import { useEffect, useState } from 'react'
import { supabase } from './supabaseClient'

export default function Avatar({ url, size, onUpload }) {
  const [avatarUrl, setAvatarUrl] = useState(null)
  const [uploading, setUploading] = useState(false)

  useEffect(() => {
    if (url) downloadImage(url)
  }, [url])

  const downloadImage = async (path) => {
    try {
      const { data, error } = await supabase.storage.from('avatars').download(path)
      if (error) {
        throw error
      }
      const url = URL.createObjectURL(data)
      setAvatarUrl(url)
    } catch (error) {
      console.log('Error downloading image: ', error.message)
    }
  }

  const uploadAvatar = async (event) => {
    try {
      setUploading(true)

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

      const file = event.target.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
      }

      onUpload(filePath)
    } catch (error) {
      alert(error.message)
    } finally {
      setUploading(false)
    }
  }

  return (
    <div style={{ width: size }} aria-live="polite">
      <img
        src={avatarUrl ? avatarUrl : `https://place-hold.it/${size}x${size}`}
        alt={avatarUrl ? 'Avatar' : 'No image'}
        className="avatar image"
        style={{ height: size, width: size }}
      />
      {uploading ? (
        'Uploading...'
      ) : (
        <>
          <label className="button primary block" htmlFor="single">
            Upload an avatar
          </label>
          <div className="visually-hidden">
            <input
              type="file"
              id="single"
              accept="image/*"
              onChange={uploadAvatar}
              disabled={uploading}
            />
          </div>
        </>
      )}
    </div>
  )
}

Add the new widget

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

src/Account.js


// Import the new component
import Avatar from './Avatar'

// ...

return (
  <div className="form-widget">
    {/* Add to the body */}
    <Avatar
      url={avatar_url}
      size={150}
      onUpload={(url) => {
        setAvatarUrl(url)
        updateProfile({ username, website, avatar_url: url })
      }}
    />
    {/* ... */}
  </div>
)