Use Supabase with Expo React Native

1. Create a Supabase project#

To start, you need a Supabase project.

Create a new Supabase project from the Dashboard of any organization you belong to.

2. Set up your database#

When your Supabase project is up and running, create an instruments table with some sample data. Then set only the privileges each Postgres role needs, add Row Level Security (RLS) for enhanced security for database data by default, and create an RLS policy to make the data in the table publicly readable.

Do these steps within your project's dashboard by copying and running the snippet in your project's SQL Editor.

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-- Create the table
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create table instruments (
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  id bigint primary key generated always as identity,
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  name text not null
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);
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-- Insert sample data into the table
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insert into instruments (name)
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values
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  ('violin'),
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  ('viola'),
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  ('cello');
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-- Grant the privileges the role needs, which is read access
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grant select on public.instruments to anon;
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-- Enable row level security for the table
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alter table instruments enable row level security;
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-- Create a policy to allow the anon role to read from the instruments table
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create policy "public can read instruments"
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on public.instruments
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for select to anon
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using (true);

3. Create an Expo app#

Create a minimal Expo app using the create-expo-app command with the blank TypeScript template.

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npx create-expo-app my-app --template blank-typescript

4. Install Agent Skills (optional)#

Supabase's Agent Skills is a curated set of instructions that give your AI agent procedural knowledge about working with Supabase.

To install, run the following command in the root of your project:

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npx skills add supabase/agent-skills

5. Install the Supabase client library#

The fastest way to get started is to use the @supabase/supabase-js client library which provides a convenient interface for working with Supabase from a React Native app.

Navigate to the Expo app and install supabase-js along with the required dependencies for session storage and URL handling.

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cd my-app && npx expo install @supabase/supabase-js react-native-url-polyfill expo-sqlite

6. Declare Supabase environment variables#

Create a .env file in the root of your project and populate it with your Supabase connection variables that you can get from the helper below, or from the project Connect panel.

Expo requires environment variables to be prefixed with EXPO_PUBLIC_ to be accessible in your app code.

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EXPO_PUBLIC_SUPABASE_URL=<SUBSTITUTE_SUPABASE_URL>
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EXPO_PUBLIC_SUPABASE_PUBLISHABLE_KEY=<SUBSTITUTE_SUPABASE_PUBLISHABLE_KEY>

Get API details#

To interact with data in database tables, you use the client libraries that wrap the auto-generated Data API endpoints, authenticating using the Project URL and key from the project Connect dialog.

7. Initialize the Supabase client#

Create a helper file at lib/supabase.ts to initialize the Supabase client using the environment variables.

The code below uses Expo's localStorage polyfill to persist authentication sessions.

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import 'react-native-url-polyfill/auto'
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import { createClient } from '@supabase/supabase-js'
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import 'expo-sqlite/localStorage/install'
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const supabaseUrl = process.env.EXPO_PUBLIC_SUPABASE_URL
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const supabasePublishableKey = process.env.EXPO_PUBLIC_SUPABASE_PUBLISHABLE_KEY
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export const supabase = createClient(supabaseUrl, supabasePublishableKey, {
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  auth: {
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    storage: localStorage,
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    autoRefreshToken: true,
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    persistSession: true,
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    detectSessionInUrl: false,
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  },
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})

8. Query data from the app#

Replace the contents of App.tsx with the following code to fetch and display the instruments from your database.

Use useEffect to fetch the data when the component mounts and display the query result using React Native components.

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import { useEffect, useState } from 'react'
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import { FlatList, StyleSheet, Text, View } from 'react-native'
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import { supabase } from './lib/supabase'
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export default function App() {
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  const [instruments, setInstruments] = useState([])
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  useEffect(() => {
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    getInstruments()
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  }, [])
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  async function getInstruments() {
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    const { data } = await supabase.from('instruments').select()
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    setInstruments(data)
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  }
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  return (
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    <View style={styles.container}>
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      <FlatList
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        data={instruments}
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        keyExtractor={(item) => item.id.toString()}
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        renderItem={({ item }) => <Text style={styles.item}>{item.name}</Text>}
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      />
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    </View>
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  )
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}
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const styles = StyleSheet.create({
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  container: {
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    flex: 1,
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    backgroundColor: '#fff',
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    paddingTop: 50,
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    paddingHorizontal: 16,
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  },
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  item: {
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    padding: 16,
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    borderBottomWidth: 1,
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    borderBottomColor: '#ccc',
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  },
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})

9. Start the app#

Run the development server and scan the QR code with the Expo Go app on your phone, or press i for iOS simulator or a for Android emulator.

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npx expo start

Next steps#

• Set up Auth for your app
• Insert more data into your database
• Upload and serve static files using Storage