Skip to content

Getting Started with prei

This tutorial will walk you through setting up the prei application and creating your first property analysis with the custom design system and underwriting engine.

Prerequisites

Before you begin, ensure you have:

  • Python 3.14 or higher installed
  • Git installed
  • Basic familiarity with command-line interfaces
  • (Optional) Docker and Docker Compose for containerized deployment

Step 1: Clone the Repository

First, clone the repository to your local machine:

git clone git@github.com:paruff/prei.git
cd prei

Step 2: Set Up Your Environment

Option A: Local Development with Virtual Environment

Create and activate a Python virtual environment:

python3.14 -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate

Install the required dependencies:

pip install -r requirements.txt

If you prefer containerized development, you can use Docker Compose:

docker compose up -d

This starts the web application with SQLite. The entrypoint automatically runs migrations and seeds the demo user — no extra commands needed.

Step 3: Configure Environment Variables

Copy the example environment file and customize it:

cp .env.example .env

Edit the .env file to set your configuration:

DEBUG=True
SECRET_KEY=your-secure-secret-key-here
ALLOWED_HOSTS=localhost,127.0.0.1

# For local development (SQLite)
# Leave DATABASE_URL commented out to use SQLite

# For PostgreSQL (local)
# DATABASE_URL=postgres://postgres:postgres@localhost:5432/investor_db

# For Docker Compose
DATABASE_URL=postgres://postgres:postgres@db:5432/investor_db

Important: Generate a secure SECRET_KEY using:

python -c "from django.core.management.utils import get_random_secret_key; print(get_random_secret_key())"

Step 4: Initialize the Database

The entrypoint runs migrations and seeds the demo user automatically on container start.

# Local development
python manage.py migrate
python manage.py seed_data

# Docker Compose (entrypoint handles it — just start the container)
docker compose up -d

Step 5: Load Sample Data (Optional, if not auto-seeded)

If the entrypoint didn't run (e.g. local virtualenv), seed the demo user manually:

python manage.py seed_data

This creates a demo user and sample properties: - Email: demo@prei.dev - Password: DemoPass123!

Create a Superuser (Optional — for Django Admin access)

Create an admin account to access the Django admin interface:

# Local development
python manage.py createsuperuser

# Docker Compose
docker compose exec web python manage.py createsuperuser

Step 6: Start the Development Server

Launch the Django development server:

# Local development
python manage.py runserver

# Docker Compose (already running)
# Access at http://localhost:8000

The application will be available at http://localhost:8000.

Step 7: Explore the Application

  1. Dashboard — Visit http://localhost:8000/ to see the deal screener dashboard with KPI grid, colour-coded verdicts, and property list
  2. Add a Property — Use the property entry form (/properties/add/) with styled inputs and responsive form grids
  3. BRRRR Calculator — Navigate to /brrrr/ to try the fully client-side BRRRR calculator
  4. Markets — Browse /markets/ for market intelligence scores per ZIP
  5. Admin Interface — Navigate to http://localhost:8000/admin for Django admin access

UI/UX Highlights

The interface is built on a custom design system with:

  • CSS custom property tokens (tokens.css) — semantic colors, spacing, typography
  • Component classes — .card, .kpi-grid, .data-table, .verdict-badge, .score-bar, .tab-bar, .brrrr-banner, .empty-state
  • Responsive layout — 4-column → 2-column → 1-column at 640px / 400px breakpoints
  • No Bootstrap — zero third-party CSS frameworks
  • Widget base classes — StyledNumberInput, StyledTextInput, StyledSelect auto-apply CSS in core/forms.py
  • Python-driven colors — score.coc_color_class properties return CSS class names; no threshold logic in templates

Step 8: Add Your First Property

  1. Click Add Property from the dashboard or navigate to /properties/add/
  2. Fill in the property details:
  3. Address, city, state, zip code
  4. Purchase price and date (e.g. $200,000)
  5. Square footage and number of units
  6. Financing details (down payment %, interest rate, loan term)
  7. Operating expenses (taxes, insurance, HOA, maintenance, capex)
  8. Save the property
  9. The dashboard will now show the property with its underwriting score and verdict

Step 9: View Investment Analysis

Each property receives a full underwriting scorecard:

  • Underwriting Score — 0–100 composite score
  • Verdict — "Strong Buy", "Conditional", or "Pass"
  • Metrics — CoC, Cap Rate, DSCR, GRM, After-Tax CoC, IRR
  • Flags — Any failing criteria with explanations
  • Color coding — Green (good), amber (warning), red (bad)

Next Steps

Now that you have the application running, explore these guides:

Troubleshooting

Database Connection Issues

If you encounter database connection errors:

  • Local: Ensure PostgreSQL is running, or remove DATABASE_URL from .env to use SQLite
  • Docker: Verify the database service is healthy with docker compose ps

Missing Static Files

If the UI appears unstyled or tests fail with Missing staticfiles manifest entry:

python manage.py collectstatic --noinput

Migration Errors

If migrations fail:

# Check migration status
python manage.py showmigrations

# Reset migrations (development only!)
python manage.py migrate core zero
python manage.py migrate

Port Already in Use

If port 8000 is already in use:

# Use a different port
python manage.py runserver 8001

Getting Help

If you encounter issues not covered here, please: