Building a Multi-Tenant Application with Next.js and Supabase

In today's fast-paced digital landscape, developing applications that can efficiently serve multiple clients—also known as multi-tenancy—has become a critical requirement for software developers. Multi-tenant applications allow businesses to share a single application instance while keeping their data isolated and secure. This article will guide you through building a multi-tenant application using Next.js and Supabase, two powerful tools in the modern web development ecosystem.

What is Multi-Tenancy?

Multi-tenancy is an architecture where a single software instance serves multiple tenants (clients) while maintaining their data privacy and security. Each tenant's data is stored in a shared database but is logically separated from other tenants. This approach reduces costs, simplifies maintenance, and improves scalability.

Use Cases for Multi-Tenant Applications

• SaaS Platforms: Software as a Service applications that serve multiple customers—think CRM systems or project management tools.
• E-Commerce Solutions: Platforms allowing multiple vendors to sell their products while managing individual inventories.
• Content Management Systems (CMS): Enabling different organizations to manage their content using a shared infrastructure.

Why Choose Next.js and Supabase?

Next.js

Next.js is a React framework that enables developers to build server-side rendered (SSR) applications efficiently. Its features include:

• Static Site Generation (SSG): Pre-render pages at build time for better performance.
• API Routes: Create backend endpoints easily within your Next.js app.
• Automatic Code Splitting: Load only the necessary JavaScript for each page.

Supabase

Supabase is an open-source alternative to Firebase that provides a set of tools to build applications quickly. Key features include:

• Real-time Database: Listen for changes in your database in real-time.
• Authentication: Simple and secure user management.
• Auto-generated APIs: Easily interact with your database.

Together, Next.js and Supabase create a powerful stack for building multi-tenant applications.

Step-by-Step Guide to Building a Multi-Tenant Application

Step 1: Setting Up Your Next.js Application

First, you need to create a Next.js application. Open your terminal and run:

npx create-next-app@latest my-multi-tenant-app
cd my-multi-tenant-app

Step 2: Installing Supabase

Next, install the Supabase client library:

npm install @supabase/supabase-js

Step 3: Initialize Supabase

Create a new file named supabaseClient.js in the root of your project. This file will handle the Supabase client initialization.

// supabaseClient.js

import { createClient } from '@supabase/supabase-js';

const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL;
const supabaseAnonKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY;

export const supabase = createClient(supabaseUrl, supabaseAnonKey);

Step 4: Setting Up the Database

1. Create a Supabase Project: Go to Supabase.io and create a new project.
2. Create Tables: Define a tenants table and a users table. The tenants table should include a unique identifier for each tenant.

-- tenants table
CREATE TABLE tenants (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) UNIQUE NOT NULL
);

-- users table
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  email VARCHAR(255) UNIQUE NOT NULL,
  tenant_id INTEGER REFERENCES tenants(id)
);

Step 5: Authentication and User Management

Next, implement authentication to manage users based on their tenant. Create a simple sign-up form in pages/signup.js:

// pages/signup.js

import { supabase } from '../supabaseClient';

export default function Signup() {
  const handleSignup = async (event) => {
    event.preventDefault();
    const { email, tenantId } = event.target.elements;

    const { user, error } = await supabase.auth.signUp({
      email: email.value,
      password: 'your-password', // Consider implementing a proper password management
    });

    if (user) {
      // Associate user with tenant
      await supabase
        .from('users')
        .insert([{ email: email.value, tenant_id: tenantId.value }]);
    } else {
      console.error(error.message);
    }
  };

  return (
    <form onSubmit={handleSignup}>
      <input name="email" type="email" placeholder="Email" required />
      <input name="tenantId" placeholder="Tenant ID" required />
      <button type="submit">Sign Up</button>
    </form>
  );
}

Step 6: Data Isolation by Tenant

When fetching data, ensure that you only retrieve data pertaining to the logged-in user’s tenant. For example, in a page component, you can do the following:

// pages/dashboard.js

import { useEffect, useState } from 'react';
import { supabase } from '../supabaseClient';

export default function Dashboard() {
  const [data, setData] = useState([]);

  useEffect(() => {
    const fetchData = async () => {
      const { user } = supabase.auth.currentUser;
      const { data: tenantsData } = await supabase
        .from('users')
        .select('tenant_id')
        .eq('email', user.email);

      const { data: tenantData } = await supabase
        .from('your_data_table')
        .eq('tenant_id', tenantsData[0].tenant_id);

      setData(tenantData);
    };

    fetchData();
  }, []);

  return (
    <div>
      {data.map(item => (
        <div key={item.id}>{item.name}</div>
      ))}
    </div>
  );
}

Step 7: Deploying Your Application

You can deploy your Next.js application to platforms like Vercel or Netlify with a few clicks. Ensure that you set your Supabase environment variables in the deployment settings.

Troubleshooting Common Issues

1. Database Connection Errors: Verify your Supabase URL and anon key are correctly set in your environment variables.
2. Authentication Failures: Ensure users are created with the correct email and check your Supabase project's authentication settings.
3. Data Not Isolated: Always filter your database queries based on the tenant_id to ensure data isolation.

Conclusion

Building a multi-tenant application using Next.js and Supabase is straightforward yet powerful. By leveraging the capabilities of these tools, you can create scalable, secure, and efficient applications that cater to multiple clients without compromising on performance or usability. With the steps outlined in this article, you now have a solid foundation to kickstart your multi-tenant project. Happy coding!