> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nativeline.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Supabase Authentication
> Add user signup, login, and session management
# Supabase Authentication
Add user accounts to your app with Supabase Auth. Users can sign up, log in, reset passwords, and maintain sessions across app launches.
## Prerequisites
* [Supabase connected](/integrations/supabase/setup)
* Your Nativeline project
***
## Setting Up Auth
Tell Nativeline what you need:
```
Add user authentication with Supabase:
- Email/password signup
- Email/password login
- Password reset
- Session persistence (stay logged in)
```
Nativeline will create:
* Auth service/manager
* Login screen
* Signup screen
* Session handling
***
## Authentication Flow
### Signup Flow
```
User enters email + password
↓
App calls Supabase signUp()
↓
Supabase creates user
↓
(Optional) Email verification
↓
User is logged in
```
### Login Flow
```
User enters email + password
↓
App calls Supabase signIn()
↓
Supabase validates credentials
↓
Session token returned
↓
User is logged in
```
### Session Persistence
Supabase handles session tokens automatically:
* Tokens stored securely
* Auto-refresh before expiry
* User stays logged in across app launches
***
## Creating Auth Screens
### Signup Screen
```
Create a signup screen with:
- Email field with validation
- Password field (minimum 6 characters)
- Confirm password field
- "Create Account" button
- Link to "Already have an account? Log in"
- Show errors inline under fields
```
### Login Screen
```
Create a login screen with:
- Email field
- Password field
- "Log In" button
- "Forgot Password?" link
- Link to "Don't have an account? Sign up"
- Show error message if login fails
```
### Password Reset
```
Add a forgot password screen:
- Email field
- "Send Reset Link" button
- Success message after sending
- Link back to login
```
***
## Handling Auth State
### Check if User is Logged In
```
When the app starts, check if the user is logged in.
If logged in, go to the home screen.
If not logged in, show the login screen.
```
### Get Current User
```
Show the current user's email on the profile screen
```
### Sign Out
```
Add a sign out button that:
- Logs the user out of Supabase
- Returns to the login screen
- Clears local session data
```
***
## Email Verification (Optional)
By default, Supabase can require email verification:
### Enable in Supabase Dashboard
1. Authentication → Settings
2. Toggle "Enable email confirmations"
3. Customize email template if desired
### Handle in App
```
After signup, show a message:
"Please check your email to verify your account"
```
### Disable for Testing
For development, you can disable email confirmation:
1. Supabase Dashboard → Authentication → Settings
2. Disable "Enable email confirmations"
***
## Protecting Data with User IDs
### Associate Data with Users
When saving data, include the user's ID:
```
When creating a new task, save the current user's ID with it
so each user only sees their own tasks.
```
### Row Level Security
In Supabase, create policies so users only see their data:
```sql theme={null}
-- Users can only see their own tasks
CREATE POLICY "Users see own tasks"
ON tasks FOR SELECT
USING (auth.uid() = user_id);
-- Users can only create tasks for themselves
CREATE POLICY "Users create own tasks"
ON tasks FOR INSERT
WITH CHECK (auth.uid() = user_id);
```
***
## Handling Auth Errors
### Common Errors
| Error | Cause | Solution |
| ------------------- | ---------------- | ------------------------------------- |
| Invalid email | Bad format | Validate email format |
| Weak password | Too short | Require 6+ characters |
| User exists | Duplicate signup | Show "Account exists, try logging in" |
| Invalid credentials | Wrong password | Show "Incorrect email or password" |
| Too many requests | Rate limited | Show "Please wait and try again" |
### Error Handling in App
```
Handle authentication errors gracefully:
- Show specific error messages
- Don't reveal if email exists (security)
- Allow retry after errors
```
***
## Auth Best Practices
Validate inputs before sending to Supabase. But also rely on Supabase's server-side validation — don't trust client validation alone.
Require at least 6 characters (Supabase default). Consider:
* Minimum 8 characters
* Mix of letters and numbers
* Password strength indicator
Let Supabase handle token refresh automatically. Don't store passwords locally. Clear sessions on logout.
When login fails, say "Invalid email or password" — not "User not found." This prevents account enumeration attacks.
***
## Testing Auth
### In Simulator
1. Create a test account
2. Verify login works
3. Close and reopen app (should stay logged in)
4. Test logout
5. Test password reset flow
### Reset Test Users
In Supabase Dashboard:
1. Authentication → Users
2. Find test user
3. Delete or modify as needed
***
## Advanced: Social Auth (Future)
Supabase supports social logins (Google, Apple, GitHub). These require additional setup:
* Apple: Requires Apple Developer account
* Google: Requires Google Cloud setup
* OAuth: Various providers
Contact Nativeline support for guidance on social auth setup.
***
## Next Steps
Store user data in tables
Upload user profile photos