Supabase Realtime Authentication

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31-08-2024

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Navigating Supabase Realtime Authentication with User Objects

Supabase's Realtime functionality offers powerful capabilities for building real-time applications. However, authenticating with user objects instead of session objects can present a challenge. This article will delve into the intricacies of this process, drawing insights from a Stack Overflow question, and provide practical solutions.

The Question:

A user on Stack Overflow was attempting to utilize Supabase Realtime to track changes in a user's profile, but encountered an "Unauthorized" error. They had a user object but lacked access to a session object, which Supabase's Realtime authentication typically relies on.

Understanding the Issue:

Supabase Realtime authentication generally requires a valid session object (containing JWT) to verify user identity. The question highlights a scenario where the application doesn't utilize session objects, leading to the "Unauthorized" error.

The Solution:

The key lies in understanding that Supabase Realtime requires a valid authentication token for authorization. While session objects usually provide this, you can directly use a JWT token obtained through Supabase's authentication system.

Here's a refined code snippet incorporating this solution:

export async function AuthenticatedNavbar({
  initialBalance,
  initialLockedBalance,
  User
}) {

  const supabase = createClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!
  );

  // 1. Obtain JWT from Supabase Authentication
  const { data: { session }, error } = await supabase.auth.getSession();
  if (error) {
    // Handle error, e.g., display an error message
    console.error("Error retrieving session:", error);
    return; 
  }

  // 2. Use the JWT from the session for Realtime authorization
  supabase.realtime.setAuth(session.access_token); 

  const channel = supabase
    .channel(`profile_changes`)
    .on('postgres_changes', {
      event: '*',
      schema: 'public',
      table: 'profile'
    }, (payload) => {
      console.log(`json stuff: ${JSON.stringify(payload)}`);
      const newProfile = payload.new as Profile;
      setProfile(newProfile);
    })
    .subscribe();
}

Explanation:

1. Obtain JWT: The code first retrieves the session object using supabase.auth.getSession(). This fetches the active session, which includes the access_token.
2. Realtime Authorization: The retrieved access_token is then passed to supabase.realtime.setAuth(). This establishes authentication for Realtime connections and enables access to the profile_changes channel.

Important Considerations:

• Authentication State: Ensure your application manages the authentication state effectively. If the user logs out, the session object will become invalid, and you'll need to re-authenticate for Realtime access.
• RLS (Row Level Security): The code assumes that the user object includes necessary information (e.g., user ID) for your RLS policies to grant access to the profile. Carefully configure RLS to control access based on the user's permissions.
• Robust Error Handling: Implement comprehensive error handling to gracefully manage authentication failures and potential issues with Realtime connections.

Additional Value:

This article goes beyond the original Stack Overflow question by offering a clear and actionable solution with detailed code explanations. It emphasizes the importance of proper JWT handling for authentication and highlights crucial aspects like session management and RLS configuration. By combining technical guidance with practical considerations, it empowers developers to confidently integrate Supabase Realtime into their applications while utilizing user objects for authentication.