v0 Database Setup Template

A comprehensive template for integrating database setup and authentication with v0

Overview

This template provides a complete foundation for building database-driven applications with v0. It includes a full Supabase authentication system and a powerful database schema extraction tool that helps v0 understand your database structure for more accurate code generation.

🤖 Why This Matters for v0's AI

The database schema extraction tool is a game-changer for v0's AI capabilities. By providing v0 with comprehensive schema information, you unlock significantly more intelligent and accurate code generation:

Enhanced Understanding

• Application Logic: v0 understands your data relationships, business rules, and domain model
• Security Context: v0 sees your RLS policies and generates security-aware queries automatically
• Data Validation: v0 knows your constraints and generates proper validation logic
• Query Optimization: v0 references your indexes to write performant queries

Better Code Generation

• Accurate SQL: Queries match your exact table structure, column types, and relationships
• Smart JOINs: v0 understands foreign keys and generates correct JOIN operations
• Type Safety: Generated TypeScript types match your actual database schema
• Error Prevention: v0 avoids referencing non-existent tables, columns, or functions

Improved Troubleshooting

• Context-Aware Debugging: v0 can identify schema mismatches and suggest fixes
• Migration Assistance: v0 understands schema changes and helps update dependent code
• RLS Policy Debugging: v0 can explain why queries might fail due to security policies
• Performance Analysis: v0 suggests index improvements based on your query patterns

Real-World Impact

Without schema context, v0 might generate: ```sql -- Generic, potentially incorrect query SELECT * FROM users WHERE id = $1 ```

With schema context, v0 generates: ```sql -- Accurate query respecting your schema, RLS, and relationships SELECT u.id, u.email, u.created_at, p.display_name, p.avatar_url FROM auth.users u LEFT JOIN public.profiles p ON u.id = p.user_id WHERE u.id = $1 -- v0 knows this respects your RLS policy: profiles are only visible to the owner ```

Bottom line: The schema extraction tool transforms v0 from a general-purpose code generator into a database-aware development partner that understands your specific application architecture.

Quick Links

• Use this template in v0 - Start building with this template
• Live Demo - See the template in action
• GitHub Repository - Clone or fork the template

What's Included

Authentication System

• Complete Supabase authentication with email/password
• Login, signup, and password reset flows
• Email confirmation handling
• Protected routes with middleware
• Row Level Security (RLS) ready

Database Schema Tool

⚠️ Important: The build-db-setup.mjs script runs locally on your machine, not in v0. You run it in your local development environment to generate schema files, then use those files in v0 for enhanced AI understanding.

The build-db-setup.mjs script extracts comprehensive database information into JSON files that v0 can reference:

• Tables: Complete structure with columns, types, and relationships
• Functions: Custom database functions and stored procedures
• Indexes: Index definitions for query optimization
• RLS Policies: Row Level Security policies for data access control
• Constraints: Foreign keys, unique constraints, and check constraints
• Triggers: Database triggers and their definitions
• Extensions: Installed Postgres extensions

Quick Start

1. Set Up Environment Variables

Add your Supabase credentials:

```env NEXT_PUBLIC_SUPABASE_URL=your_supabase_url NEXT_PUBLIC_SUPABASE_ANON_KEY=your_supabase_anon_key NEXT_PUBLIC_DEV_SUPABASE_REDIRECT_URL=http://localhost:3000 ```

Example Mode (Optional)

To preview the template without setting up Supabase:

```env NEXT_PUBLIC_EXAMPLE_MODE=true ```

This allows you to explore the UI and pages without connecting a real database. Authentication will show example error messages, and protected routes will be accessible.

For database schema extraction, add your database connection:

```env POSTGRES_URL_WITH_PASSWORD=postgres://user:password@host:5432/database ```

Or use individual variables:

```env POSTGRES_HOST=db.yourproject.supabase.co POSTGRES_PORT=5432 POSTGRES_DATABASE=postgres POSTGRES_USER=postgres POSTGRES_PASSWORD=your_password ```

2. Generate Database Schema

📍 Run this locally: This command runs on your local machine, not in v0.

Extract your database schema for v0:

```bash npm run build:db-setup ```

This creates a db-setup/ directory with JSON files containing your complete database structure.

3. Start Development

```bash npm install npm run dev ```

Visit http://localhost:3000 to see the template in action.

Database Schema Benefits

With the generated schema files, v0 gains deep insight into your application:

Query Generation

• Generate accurate SQL queries matching your exact table structure
• Understand foreign key relationships for proper JOIN operations
• Reference the correct column types and handle nullable fields appropriately
• Use existing indexes for optimized query performance

Security & Validation

• Respect RLS policies when generating security-aware queries
• Understand constraints (unique, check, foreign key) for proper validation
• Generate code that aligns with your security model
• Avoid common security pitfalls by understanding your access control

Advanced Features

• Utilize custom functions and stored procedures in generated code
• Understand triggers and their side effects
• Reference installed extensions (like PostGIS, pg_vector)
• Generate migration-safe code that respects your schema evolution

Developer Experience

• Get accurate TypeScript types derived from your actual schema
• Receive context-aware suggestions and completions
• Debug issues faster with schema-aware error messages
• Maintain consistency between database and application code

Keeping Schema Updated

💡 Tip: Run this command locally whenever your database schema changes.

Run the schema extraction whenever you:

• Add or modify tables
• Create new functions or triggers
• Update RLS policies
• Change constraints or indexes

```bash npm run build:db-setup ```

Project Structure

``` ├── app/ │ ├── auth/ # Authentication pages and routes │ ├── protected/ # Example protected route │ └── page.tsx # Landing page ├── components/ # Reusable components │ ├── login-form.tsx │ ├── sign-up-form.tsx │ └── ... ├── lib/ │ └── supabase/ # Supabase client utilities ├── scripts/ │ └── build-db-setup.mjs # Database schema extraction ├── db-setup/ │ ├── scripts/ # SQL query scripts │ └── *.json # Generated schema files └── middleware.ts # Session management ```

Documentation

For detailed setup instructions and troubleshooting, see:

• Database Schema Setup Guide
• Environment Variables Guide

Deployment

This template is deployed at:

https://v0-supabase-authentication-system-psi.vercel.app/

Use This Template

Get started with this template on v0:

https://v0.app/templates/Osn3Xx2aDmE

Or clone from GitHub:

https://github.com/headline-design/v0-db-setup-template

How It Works

1. Use this template on v0.app or clone from GitHub
2. Connect your Supabase project and run the database schema extraction
3. Build and modify your project using v0's AI-powered development
4. Deploy to Vercel with automatic updates from your repository

Why This Template?

This template bridges the gap between v0's AI-powered development and real-world database applications. By providing v0 with comprehensive schema information, you get more accurate code generation, better query optimization, and security-aware database interactions.