React Native file upload with Supabase Storage

2023-08-01

21 minute read

If you want to upload files from your React Native app, you need a backend to store the files, Supabase Storage is a great choice for this as it provides a simple API to upload files, and we can easily combine this with authentication to build a powerful app.

This means you can quickly build your own image-sharing app, a file-sharing app, or any other app that needs to upload files to a backend!

In this tutorial, you will learn to:

You can also directly check out the full source code on Github so you can get started with Supabase fast!

Before we get into the app, let's quickly start a new Supabase project.

Creating the Supabase Project

To use authentication and storage we need a new Supabase project. If you don't have a Supabase account yet, you can get started for free!

In your dashboard, click "New Project" and leave it to the default settings, but make sure you keep a copy of your Database password!

After a minute your project should be ready, and we can configure the authentication and storage.

Setting up Authentication

Authentication will be enabled by default, but we want to turn off email confirmation for this tutorial.

Select Authentication from the menu, go to the Providers section, and expand Email.

Here you can disable the confirmation email, and apply other changes later if you want to!

Setting up Storage

Now we want to create a bucket under storage where we will upload our files, and also add some security rules to protect the files of a user.

First, select Storage from the menu, then click New bucket and call it files.

Make sure that this is not a public bucket, otherwise, even unauthenticated users can upload or read the files!

To protect that bucket and allow users only access to their own folder, we need to add some Storage policies.

You can either do this through the UI and pick from examples, or simply run my SQL script in the SQL Editor which you can select from the menu:


_10
CREATE POLICY "Enable storage access for users based on user_id" ON "storage"."objects"
_10
AS PERMISSIVE FOR ALL
_10
TO public
_10
USING (bucket_id = 'files' AND (SELECT auth.uid()::text )= (storage.foldername(name))[1])
_10
WITH CHECK (bucket_id = 'files' AND (SELECT auth.uid()::text) = (storage.foldername(name))[1])

This will allow users to only access their own folder, and not any other files in the bucket.

Setting up the React Native app

Now that we have our Supabase project ready, we can start building the React Native app!

Get started by setting up a new Expo app with the tabs template and install some dependencies:


_10
# Create a new Expo app
_10
npx create-expo-app@latest cloudApp --template tabs@49
_10
_10
# Install dependencies
_10
npm i @supabase/supabase-js
_10
npm i react-native-url-polyfill base64-arraybuffer react-native-loading-spinner-overlay @react-native-async-storage/async-storage
_10
_10
# Install Expo packages
_10
npx expo install expo-image-picker
_10
npx expo install expo-file-system

We will use the Expo AsyncStorage to store the Supabase session, and the Expo Image Picker to select images from the device. We also need the Expo File System to read the image from the device and upload its data.

You can now already run your project with npx expo and then select a platform to run on.

However, the tabs template contains a lot of code that we don't need, so to simplify things we can remove the app, constants and components folder.

This gives us a much cleaner project structure.

Connecting to Supabase from React Native

To use Supabase we need to initialize the client with our project URL and the public key, which you can find in the Settings of your project under API.

You can put both of them in a .env file at the root of your project:


_10
EXPO_PUBLIC_SUPABASE_URL=
_10
EXPO_PUBLIC_SUPABASE_ANON_KEY=

We can now simply read those values from the environment variables and initialize the Supabase client, so create a file at config/initSupabase.ts and add the following code:


_15
import AsyncStorage from '@react-native-async-storage/async-storage'
_15
import 'react-native-url-polyfill/auto'
_15
_15
import { createClient } from '@supabase/supabase-js'
_15
_15
const url = process.env.EXPO_PUBLIC_SUPABASE_URL
_15
const key = process.env.EXPO_PUBLIC_SUPABASE_ANON_KEY
_15
_15
// Initialize the Supabase client
_15
export const supabase = createClient(url, key, {
_15
auth: {
_15
storage: AsyncStorage,
_15
detectSessionInUrl: false,
_15
},
_15
})

We are using the AsyncStorage from Expo to handle the session of our Supabase client and add in the createClient function.

Later we can import the supabase client from this file and use it in our app whenever we need to access Supabase.

Building the authentication flow

Currently, the app won't work as we have no entry point. Because we are using the Expon Router and file-based routing, we can create a new file at app/index.tsx which will be the first page that comes up in our app.

On this page we will handle both login and registration, so let's start by creating a simple form with a few inputs and buttons inside the app/index.tsx file:


_98
import { Alert, View, Button, TextInput, StyleSheet, Text, TouchableOpacity } from 'react-native'
_98
import { useState } from 'react'
_98
import React from 'react'
_98
import Spinner from 'react-native-loading-spinner-overlay'
_98
import { supabase } from '../config/initSupabase'
_98
_98
const Login = () => {
_98
const [email, setEmail] = useState('')
_98
const [password, setPassword] = useState('')
_98
const [loading, setLoading] = useState(false)
_98
_98
// Sign in with email and password
_98
const onSignInPress = async () => {
_98
setLoading(true)
_98
_98
const { error } = await supabase.auth.signInWithPassword({
_98
email,
_98
password,
_98
})
_98
_98
if (error) Alert.alert(error.message)
_98
setLoading(false)
_98
}
_98
_98
// Create a new user
_98
const onSignUpPress = async () => {
_98
setLoading(true)
_98
const { error } = await supabase.auth.signUp({
_98
email: email,
_98
password: password,
_98
})
_98
_98
if (error) Alert.alert(error.message)
_98
setLoading(false)
_98
}
_98
_98
return (
_98
<View style={styles.container}>
_98
<Spinner visible={loading} />
_98
_98
<Text style={styles.header}>My Cloud</Text>
_98
_98
<TextInput
_98
autoCapitalize="none"
_98
placeholder="john@doe.com"
_98
value={email}
_98
onChangeText={setEmail}
_98
style={styles.inputField}
_98
/>
_98
<TextInput
_98
placeholder="password"
_98
value={password}
_98
onChangeText={setPassword}
_98
secureTextEntry
_98
style={styles.inputField}
_98
/>
_98
_98
<TouchableOpacity onPress={onSignInPress} style={styles.button}>
_98
<Text style={{ color: '#fff' }}>Sign in</Text>
_98
</TouchableOpacity>
_98
<Button onPress={onSignUpPress} title="Create Account" color={'#fff'}></Button>
_98
</View>
_98
)
_98
}
_98
_98
const styles = StyleSheet.create({
_98
container: {
_98
flex: 1,
_98
paddingTop: 200,
_98
padding: 20,
_98
backgroundColor: '#151515',
_98
},
_98
header: {
_98
fontSize: 30,
_98
textAlign: 'center',
_98
margin: 50,
_98
color: '#fff',
_98
},
_98
inputField: {
_98
marginVertical: 4,
_98
height: 50,
_98
borderWidth: 1,
_98
borderColor: '#2b825b',
_98
borderRadius: 4,
_98
padding: 10,
_98
color: '#fff',
_98
backgroundColor: '#363636',
_98
},
_98
button: {
_98
marginVertical: 15,
_98
alignItems: 'center',
_98
backgroundColor: '#2b825b',
_98
padding: 12,
_98
borderRadius: 4,
_98
},
_98
})
_98
_98
export default Login

There's nothing fancy going on here, but this is all we need to use Supabase Authentication in our app!

You can try it out right now and create a new user account or sign in with an existing one and log the values to the console to see what's going on.

However, we are not handling the authentication state yet so let's create a Context to listen to changes.

We will wrap a Provider around our app, which will use the onAuthStateChange function from Supabase to listen to changes in the authentication state and accordingly set our state.

For this, create a new file at provider/AuthProvider.tsx and add the following code:


_49
import React, { useState, useEffect, createContext, PropsWithChildren } from 'react'
_49
import { Session, User } from '@supabase/supabase-js'
_49
import { supabase } from '../config/initSupabase'
_49
_49
type AuthProps = {
_49
user: User | null
_49
session: Session | null
_49
initialized?: boolean
_49
signOut?: () => void
_49
}
_49
_49
export const AuthContext = createContext<Partial<AuthProps>>({})
_49
_49
// Custom hook to read the context values
_49
export function useAuth() {
_49
return React.useContext(AuthContext)
_49
}
_49
_49
export const AuthProvider = ({ children }: PropsWithChildren) => {
_49
const [user, setUser] = useState<User | null>()
_49
const [session, setSession] = useState<Session | null>(null)
_49
const [initialized, setInitialized] = useState<boolean>(false)
_49
_49
useEffect(() => {
_49
// Listen for changes to authentication state
_49
const { data } = supabase.auth.onAuthStateChange(async (event, session) => {
_49
setSession(session)
_49
setUser(session ? session.user : null)
_49
setInitialized(true)
_49
})
_49
return () => {
_49
data.subscription.unsubscribe()
_49
}
_49
}, [])
_49
_49
// Log out the user
_49
const signOut = async () => {
_49
await supabase.auth.signOut()
_49
}
_49
_49
const value = {
_49
user,
_49
session,
_49
initialized,
_49
signOut,
_49
}
_49
_49
return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>
_49
}

To use the context we can now wrap it around our app, and while we do this we can also take care of the navigation:

In the topmost layout file we can check whether a user has an active session or not, and either directly sign the user into the inside area (that we will create soon) or automatically bring her back to the login screen.

To make this work with the Expo Router we can create a file at app/_layout.tsx and add the following code:


_38
import { Slot, useRouter, useSegments } from 'expo-router'
_38
import { useEffect } from 'react'
_38
import { AuthProvider, useAuth } from '../provider/AuthProvider'
_38
_38
// Makes sure the user is authenticated before accessing protected pages
_38
const InitialLayout = () => {
_38
const { session, initialized } = useAuth()
_38
const segments = useSegments()
_38
const router = useRouter()
_38
_38
useEffect(() => {
_38
if (!initialized) return
_38
_38
// Check if the path/url is in the (auth) group
_38
const inAuthGroup = segments[0] === '(auth)'
_38
_38
if (session && !inAuthGroup) {
_38
// Redirect authenticated users to the list page
_38
router.replace('/list')
_38
} else if (!session) {
_38
// Redirect unauthenticated users to the login page
_38
router.replace('/')
_38
}
_38
}, [session, initialized])
_38
_38
return <Slot />
_38
}
_38
_38
// Wrap the app with the AuthProvider
_38
const RootLayout = () => {
_38
return (
_38
<AuthProvider>
_38
<InitialLayout />
_38
</AuthProvider>
_38
)
_38
}
_38
_38
export default RootLayout

Whenever the initialized or session state changes, we check if the user is authenticated and redirect her to the correct page.

This also means we don't have to worry about the authentication state in our pages anymore, we can just assume that the user is authenticated and use the useAuth hook to access the user and session data later on.

Your app might show an error right now because the /list route doesn't exist yet, but we will create it in the next step.

File Upload to Supabase Storage

Now that we have the authentication set up, we can start working on the file upload.

First, let's define another layout for this inside area so create a file at /app/(auth)/_layout.tsx and add the following code:


_35
import { Stack } from 'expo-router'
_35
import { useAuth } from '../../provider/AuthProvider'
_35
import React from 'react'
_35
import { TouchableOpacity } from 'react-native'
_35
import { Ionicons } from '@expo/vector-icons'
_35
_35
// Simple stack layout within the authenticated area
_35
const StackLayout = () => {
_35
const { signOut } = useAuth()
_35
_35
return (
_35
<Stack
_35
screenOptions={{
_35
headerStyle: {
_35
backgroundColor: '#0f0f0f',
_35
},
_35
headerTintColor: '#fff',
_35
}}
_35
>
_35
<Stack.Screen
_35
name="list"
_35
options={{
_35
headerTitle: 'My Files',
_35
headerRight: () => (
_35
<TouchableOpacity onPress={signOut}>
_35
<Ionicons name="log-out-outline" size={30} color={'#fff'} />
_35
</TouchableOpacity>
_35
),
_35
}}
_35
></Stack.Screen>
_35
</Stack>
_35
)
_35
}
_35
_35
export default StackLayout

This defines a simple stack navigation and adds a button to trigger the logout, so we can now also fully test the authentication flow.

Next, we create the page for uploading and displaying all files of a user from Supabase Storage.

You won't have any files to show yet, but loading the files of a user is as easy as calling list() on the storage bucket and passing the user id as the folder name.

Additionally, we add a little FAB (floating action button) to trigger the file picker, so create a file at /app/(auth)/list.tsx and add the following code:


_63
import { View, StyleSheet, TouchableOpacity, ScrollView } from 'react-native'
_63
import React, { useEffect, useState } from 'react'
_63
import { Ionicons } from '@expo/vector-icons'
_63
import * as ImagePicker from 'expo-image-picker'
_63
import { useAuth } from '../../provider/AuthProvider'
_63
import * as FileSystem from 'expo-file-system'
_63
import { decode } from 'base64-arraybuffer'
_63
import { supabase } from '../../config/initSupabase'
_63
import { FileObject } from '@supabase/storage-js'
_63
_63
const list = () => {
_63
const { user } = useAuth()
_63
const [files, setFiles] = useState<FileObject[]>([])
_63
_63
useEffect(() => {
_63
if (!user) return
_63
_63
// Load user images
_63
loadImages()
_63
}, [user])
_63
_63
const loadImages = async () => {
_63
const { data } = await supabase.storage.from('files').list(user!.id)
_63
if (data) {
_63
setFiles(data)
_63
}
_63
}
_63
_63
const onSelectImage = async () => {
_63
// TODO
_63
}
_63
_63
return (
_63
<View style={styles.container}>
_63
{/* FAB to add images */}
_63
<TouchableOpacity onPress={onSelectImage} style={styles.fab}>
_63
<Ionicons name="camera-outline" size={30} color={'#fff'} />
_63
</TouchableOpacity>
_63
</View>
_63
)
_63
}
_63
_63
const styles = StyleSheet.create({
_63
container: {
_63
flex: 1,
_63
padding: 20,
_63
backgroundColor: '#151515',
_63
},
_63
fab: {
_63
borderWidth: 1,
_63
alignItems: 'center',
_63
justifyContent: 'center',
_63
width: 70,
_63
position: 'absolute',
_63
bottom: 40,
_63
right: 30,
_63
height: 70,
_63
backgroundColor: '#2b825b',
_63
borderRadius: 100,
_63
},
_63
})
_63
_63
export default list

This should give us a nice and clean UI.

Now we can implement the image picker and upload the selected image to Supabase Storage.

Using the image picker from Expo gives us a URI, which we can use to read the file from the file system and convert it to a base64 string.

We can then use the upload() method from the storage client to upload the file to the storage bucket. Life can be easy.

At this point, you should be able to upload files to Supabase Storage, and you can already see them in your UI (or log them to the console).

To finally display them we will add a ScrollView component, which will render one item for every file of a user.

Let's start by creating those component rows in another file, so create a components/ImageItem.tsx file and add the following code:


_46
import { FileObject } from '@supabase/storage-js'
_46
import { Image, View, Text, TouchableOpacity } from 'react-native'
_46
import { supabase } from '../config/initSupabase'
_46
import { useState } from 'react'
_46
import { Ionicons } from '@expo/vector-icons'
_46
_46
// Image item component that displays the image from Supabase Storage and a delte button
_46
const ImageItem = ({
_46
item,
_46
userId,
_46
onRemoveImage,
_46
}: {
_46
item: FileObject
_46
userId: string
_46
onRemoveImage: () => void
_46
}) => {
_46
const [image, setImage] = useState<string>('')
_46
_46
supabase.storage
_46
.from('files')
_46
.download(`${userId}/${item.name}`)
_46
.then(({ data }) => {
_46
const fr = new FileReader()
_46
fr.readAsDataURL(data!)
_46
fr.onload = () => {
_46
setImage(fr.result as string)
_46
}
_46
})
_46
_46
return (
_46
<View style={{ flexDirection: 'row', margin: 1, alignItems: 'center', gap: 5 }}>
_46
{image ? (
_46
<Image style={{ width: 80, height: 80 }} source={{ uri: image }} />
_46
) : (
_46
<View style={{ width: 80, height: 80, backgroundColor: '#1A1A1A' }} />
_46
)}
_46
<Text style={{ flex: 1, color: '#fff' }}>{item.name}</Text>
_46
{/* Delete image button */}
_46
<TouchableOpacity onPress={onRemoveImage}>
_46
<Ionicons name="trash-outline" size={20} color={'#fff'} />
_46
</TouchableOpacity>
_46
</View>
_46
)
_46
}
_46
_46
export default ImageItem

This component will display the image from Supabase Storage, the name of the file and a delete button.

To display the image we use the download() method from the storage client, which returns a FileObject with the file data. We can then use the FileReader to convert the file data to a base64 string, which we can use as the image source.

Now let's use this component in our list.tsx file to render the list of images by updating the return statement:


_19
return (
_19
<View style={styles.container}>
_19
<ScrollView>
_19
{files.map((item, index) => (
_19
<ImageItem
_19
key={item.id}
_19
item={item}
_19
userId={user!.id}
_19
onRemoveImage={() => onRemoveImage(item, index)}
_19
/>
_19
))}
_19
</ScrollView>
_19
_19
{/* FAB to add images */}
_19
<TouchableOpacity onPress={onSelectImage} style={styles.fab}>
_19
<Ionicons name="camera-outline" size={30} color={'#fff'} />
_19
</TouchableOpacity>
_19
</View>
_19
)

Don't forget to also include the import to the ImageItem component!

Finally, we can also include the delete functionality by adding the following code to the list.tsx:


_10
const onRemoveImage = async (item: FileObject, listIndex: number) => {
_10
supabase.storage.from('files').remove([`${user!.id}/${item.name}`])
_10
const newFiles = [...files]
_10
newFiles.splice(listIndex, 1)
_10
setFiles(newFiles)
_10
}

We are handling the deletion here so we can accordingly update the state of the files list after removing an item.

And with that in place, you have a fully functional image gallery app with React Native and Supabase Storage!

What about resumable uploads?

Initially, I wanted to include resumable uploads in this tutorial, but apparently, the Uppy client didn't work 100% for React Native yet.

You can still see an initial implementation of resumable downloads with Supabase and React Native in the repository of this tutorial.

However, ultimately the uploaded file was always 0 bytes, so I decided to leave it out for now.

The Supabase team is investigating this issue, so I'm very sure that we will have resumable uploads working with React Native soon.

Conclusion

It's almost too easy to use Supabase Storage, and it's a great way to store files for your apps.

You now have a fully functional image gallery app with React Native and Supabase Storage including user authentication without writing a line of backend code!

You can find the full code of this tutorial on Github where you just need to insert your own Supabase URL and API key.

If you enjoyed the tutorial, you can learn React Native on Galaxies.dev where I help developers build awesome React Native apps.

Until next time and happy coding with Supabase!

More React Native/Expo resources

Share this article

Build in a weekend, scale to millions