Quickstart: React

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 React app from scratch.

Initialize a React app#

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

1npx create-react-app supabase-react
2cd supabase-react

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

1npm install @supabase/supabase-js

And finally we want to save the environment variables in a .env.local file. All we need are the API URL and the anon key that you copied earlier.

1REACT_APP_SUPABASE_URL=YOUR_SUPABASE_URL
2REACT_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.

Create and edit 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.

Create and edit 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 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 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:

1npm 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:

Create and edit 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 at src/Account.js:

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

// ...

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

Storage management#

If you upload additional profile photos, they'll accumulate in the avatars bucket because of their random names with only the latest being referenced from public.profiles and the older versions getting orphaned.

To automatically remove obsolete storage objects, extend the database triggers. Note that it is not sufficient to delete the objects from the storage.objects table because that would orphan and leak the actual storage objects in the S3 backend. Instead, invoke the storage API within Postgres via the http extension.

Enable the http extension for the extensions schema in the Dashboard. Then, define the following SQL functions in the SQL Editor to delete storage objects via the API:

create or replace function delete_storage_object(bucket text, object text, out status int, out content varchar)
returns record
language 'plpgsql'
security definer
as $$
declare
  project_url varchar := '<YOURPROJECTURL>';
  service_role_key varchar := '<YOURSERVICEROLEKEY>'; --  full access needed
  url varchar := project_url||'/storage/v1/object/'||bucket||'/'||object;
begin
  select
      into status, content
           result.status::int, result.content::varchar
      FROM extensions.http((
    'DELETE',
    url,
    ARRAY[extensions.http_header('authorization','Bearer '||service_role_key)],
    NULL,
    NULL)::extensions.http_request) as result;
end;
$$;

create or replace function delete_avatar(avatar_url text, out status int, out content varchar)
returns record
language 'plpgsql'
security definer
as $$
begin
  select
      into status, content
           result.status, result.content
      from public.delete_storage_object('avatars', avatar_url) as result;
end;
$$;

Next, add a trigger that removes any obsolete avatar whenever the profile is updated or deleted:

create or replace function delete_old_avatar()
returns trigger
language 'plpgsql'
security definer
as $$
declare
  status int;
  content varchar;
begin
  if coalesce(old.avatar_url, '') <> ''
      and (tg_op = 'DELETE' or (old.avatar_url <> new.avatar_url)) then
    select
      into status, content
      result.status, result.content
      from public.delete_avatar(old.avatar_url) as result;
    if status <> 200 then
      raise warning 'Could not delete avatar: % %', status, content;
    end if;
  end if;
  if tg_op = 'DELETE' then
    return old;
  end if;
  return new;
end;
$$;

create trigger before_profile_changes
  before update of avatar_url or delete on public.profiles
  for each row execute function public.delete_old_avatar();

Finally, delete the public.profile row before a user is deleted. If this step is omitted, you won't be able to delete users without first manually deleting their avatar image.

create or replace function delete_old_profile()
returns trigger
language 'plpgsql'
security definer
as $$
begin
  delete from public.profiles where id = old.id;
  return old;
end;
$$;

create trigger before_delete_user
  before delete on auth.users
  for each row execute function public.delete_old_profile();

Next steps#

At this stage you have a fully functional application!

• Got a question? Ask here.
• Sign in: app.supabase.com