Build a User Management App with Expo

This tutorial demonstrates how to build a basic user management app. The app authenticates and identifies the user, stores their profile information in the database, and allows the user to log in, update their profile details, and upload a profile photo. The app uses:

• Supabase Database - a Postgres database for storing your user data and Row Level Security so data is protected and users can only access their own information.
• Supabase Auth - users log in through magic links sent to their email (without having to set up passwords).
• Supabase Storage - users can upload a profile photo.

Project setup#

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. Create a new project in the Supabase Dashboard.
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.

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 Project URL and anon key from the API settings.

1. Go to the API Settings page in the Dashboard.
2. Find your Project URL, anon, and service_role keys on this page.

Building the App#

Let's start building the React Native app from scratch.

Initialize a React Native app#

We can use expo to initialize an app called expo-user-management:

1npx create-expo-app -t expo-template-blank-typescript expo-user-management
2
3cd expo-user-management

Then let's install the additional dependencies: supabase-js

1npm install @supabase/supabase-js
2npm install react-native-elements @react-native-async-storage/async-storage react-native-url-polyfill

Now let's create a helper file to initialize the Supabase client. We need the API URL and the anon key that you copied earlier. These variables will be exposed on the browser, and that's completely fine since we have Row Level Security enabled on our Database.

import AsyncStorage from '@react-native-async-storage/async-storage'
import { createClient } from '@supabase/supabase-js'

const supabaseUrl = YOUR_REACT_NATIVE_SUPABASE_URL
const supabaseAnonKey = YOUR_REACT_NATIVE_SUPABASE_ANON_KEY

export const supabase = createClient(supabaseUrl, supabaseAnonKey, {
  auth: {
    storage: AsyncStorage as any,
    autoRefreshToken: true,
    persistSession: true,
    detectSessionInUrl: false,
  },
})

Set up a Login component#

Let's set up a React Native component to manage logins and sign ups. Users would be able to sign in with their email and password.

import React, { useState } from 'react'
import { Alert, StyleSheet, View } from 'react-native'
import { supabase } from '../lib/supabase'
import { Button, Input } from 'react-native-elements'

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

  async function signInWithEmail() {
    setLoading(true)
    const { error } = await supabase.auth.signInWithPassword({
      email: email,
      password: password,
    })

    if (error) Alert.alert(error.message)
    setLoading(false)
  }

  async function signUpWithEmail() {
    setLoading(true)
    const { error } = await supabase.auth.signUp({
      email: email,
      password: password,
    })

    if (error) Alert.alert(error.message)
    setLoading(false)
  }

  return (
    <View style={styles.container}>
      <View style={[styles.verticallySpaced, styles.mt20]}>
        <Input
          label="Email"
          leftIcon={{ type: 'font-awesome', name: 'envelope' }}
          onChangeText={(text) => setEmail(text)}
          value={email}
          placeholder="email@address.com"
          autoCapitalize={'none'}
        />
      </View>
      <View style={styles.verticallySpaced}>
        <Input
          label="Password"
          leftIcon={{ type: 'font-awesome', name: 'lock' }}
          onChangeText={(text) => setPassword(text)}
          value={password}
          secureTextEntry={true}
          placeholder="Password"
          autoCapitalize={'none'}
        />
      </View>
      <View style={[styles.verticallySpaced, styles.mt20]}>
        <Button title="Sign in" disabled={loading} onPress={() => signInWithEmail()} />
      </View>
      <View style={styles.verticallySpaced}>
        <Button title="Sign up" disabled={loading} onPress={() => signUpWithEmail()} />
      </View>
    </View>
  )
}

const styles = StyleSheet.create({
  container: {
    marginTop: 40,
    padding: 12,
  },
  verticallySpaced: {
    paddingTop: 4,
    paddingBottom: 4,
    alignSelf: 'stretch',
  },
  mt20: {
    marginTop: 20,
  },
})

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.tsx.

import { useState, useEffect } from 'react'
import { supabase } from '../lib/supabase'
import { StyleSheet, View, Alert } from 'react-native'
import { Button, Input } from 'react-native-elements'
import { Session } from '@supabase/supabase-js'

export default function Account({ session }: { session: Session }) {
  const [loading, setLoading] = useState(true)
  const [username, setUsername] = useState('')
  const [website, setWebsite] = useState('')
  const [avatarUrl, setAvatarUrl] = useState('')

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

  async function getProfile() {
    try {
      setLoading(true)
      if (!session?.user) throw new Error('No user on the session!')

      let { data, error, status } = await supabase
        .from('profiles')
        .select(`username, website, avatar_url`)
        .eq('id', session?.user.id)
        .single()
      if (error && status !== 406) {
        throw error
      }

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

  async function updateProfile({
    username,
    website,
    avatar_url,
  }: {
    username: string
    website: string
    avatar_url: string
  }) {
    try {
      setLoading(true)
      if (!session?.user) throw new Error('No user on the session!')

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

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

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

  return (
    <View style={styles.container}>
      <View style={[styles.verticallySpaced, styles.mt20]}>
        <Input label="Email" value={session?.user?.email} disabled />
      </View>
      <View style={styles.verticallySpaced}>
        <Input label="Username" value={username || ''} onChangeText={(text) => setUsername(text)} />
      </View>
      <View style={styles.verticallySpaced}>
        <Input label="Website" value={website || ''} onChangeText={(text) => setWebsite(text)} />
      </View>

      <View style={[styles.verticallySpaced, styles.mt20]}>
        <Button
          title={loading ? 'Loading ...' : 'Update'}
          onPress={() => updateProfile({ username, website, avatar_url: avatarUrl })}
          disabled={loading}
        />
      </View>

      <View style={styles.verticallySpaced}>
        <Button title="Sign Out" onPress={() => supabase.auth.signOut()} />
      </View>
    </View>
  )
}

const styles = StyleSheet.create({
  container: {
    marginTop: 40,
    padding: 12,
  },
  verticallySpaced: {
    paddingTop: 4,
    paddingBottom: 4,
    alignSelf: 'stretch',
  },
  mt20: {
    marginTop: 20,
  },
})

Launch!#

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

import 'react-native-url-polyfill/auto'
import { useState, useEffect } from 'react'
import { supabase } from './lib/supabase'
import Auth from './components/Auth'
import Account from './components/Account'
import { View } from 'react-native'
import { Session } from '@supabase/supabase-js'

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

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

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

  return (
    <View>
      {session && session.user ? <Account key={session.user.id} session={session} /> : <Auth />}
    </View>
  )
}

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

1npm start

And then press the appropriate key for the environment you want to test the app in 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.

Additional dependency installation#

You will need a file picker that works on the environment you will build the project for, we will use react-native-document-picker in this example.

1expo install react-native-document-picker

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:

import { useState, useEffect } from 'react'
import { supabase } from '../lib/supabase'
import { StyleSheet, View, Alert, Image, Button } from 'react-native'
import DocumentPicker, { isCancel, isInProgress, types } from 'react-native-document-picker'

interface Props {
  size: number
  url: string | null
  onUpload: (filePath: string) => void
}

export default function Avatar({ url, size = 150, onUpload }: Props) {
  const [uploading, setUploading] = useState(false)
  const [avatarUrl, setAvatarUrl] = useState<string | null>(null)
  const avatarSize = { height: size, width: size }

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

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

      if (error) {
        throw error
      }

      const fr = new FileReader()
      fr.readAsDataURL(data)
      fr.onload = () => {
        setAvatarUrl(fr.result as string)
      }
    } catch (error) {
      if (error instanceof Error) {
        console.log('Error downloading image: ', error.message)
      }
    }
  }

  async function uploadAvatar() {
    try {
      setUploading(true)

      const file = await DocumentPicker.pickSingle({
        presentationStyle: 'fullScreen',
        copyTo: 'cachesDirectory',
        type: types.images,
        mode: 'open',
      })

      const photo = {
        uri: file.fileCopyUri,
        type: file.type,
        name: file.name,
      }

      const formData = new FormData()
      formData.append('file', photo)

      const fileExt = file.name.split('.').pop()
      const filePath = `${Math.random()}.${fileExt}`

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

      if (error) {
        throw error
      }

      onUpload(filePath)
    } catch (error) {
      if (isCancel(error)) {
        console.warn('cancelled')
        // User cancelled the picker, exit any dialogs or menus and move on
      } else if (isInProgress(error)) {
        console.warn('multiple pickers were opened, only the last will be considered')
      } else if (error instanceof Error) {
        Alert.alert(error.message)
      } else {
        throw error
      }
    } finally {
      setUploading(false)
    }
  }

  return (
    <View>
      {avatarUrl ? (
        <Image
          source={{ uri: avatarUrl }}
          accessibilityLabel="Avatar"
          style={[avatarSize, styles.avatar, styles.image]}
        />
      ) : (
        <View style={[avatarSize, styles.avatar, styles.noImage]} />
      )}
      <View>
        <Button
          title={uploading ? 'Uploading ...' : 'Upload'}
          onPress={uploadAvatar}
          disabled={uploading}
        />
      </View>
    </View>
  )
}

const styles = StyleSheet.create({
  avatar: {
    borderRadius: 5,
    overflow: 'hidden',
    maxWidth: '100%',
  },
  image: {
    objectFit: 'cover',
    paddingTop: 0,
  },
  noImage: {
    backgroundColor: '#333',
    border: '1px solid rgb(200, 200, 200)',
    borderRadius: 5,
  },
})

Add the new widget#

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

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

// ...
  return (
    <View>
      {/* Add to the body */}
      <View>
        <Avatar
          size={200}
          url={avatarUrl}
          onUpload={(url: string) => {
            setAvatarUrl(url)
            updateProfile({ username, website, avatar_url: url })
          }}
        />
      </View>
      {/* ... */}
    </View>
  )
}
// ...

Now you will need to run the prebuild command to get the application working on your chosen platform.

1expo prebuild

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

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

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();

At this stage you have a fully functional application!