# Quick Start Guide - Python Backend

## Step-by-Step Setup

### 1. Install Python
Make sure you have Python 3.8 or higher installed:
```bash
python --version
```

### 2. Create Virtual Environment
```bash
cd backend
python -m venv venv
```

### 3. Activate Virtual Environment

**Windows:**
```powershell
.\venv\Scripts\Activate.ps1
```

**Linux/Mac:**
```bash
source venv/bin/activate
```

### 4. Install Dependencies
```bash
pip install -r requirements.txt
```

### 5. Verify Database Connection
Make sure MySQL is running and the database `myapp` exists:
```sql
CREATE DATABASE IF NOT EXISTS myapp;
```

### 6. Run the Server
```bash
python start.py
```

Or:
```bash
python app.py
```

The server should now be running at `http://0.0.0.0:3000`

## Testing the API

Test if the server is working:
```bash
curl http://localhost:3000/api/training-projects
```

## Common Issues

### ModuleNotFoundError
If you get import errors, make sure you've activated the virtual environment and installed all dependencies.

### Database Connection Error
Check that:
- MySQL is running
- Database credentials in `app.py` are correct
- Database `myapp` exists

### Port Already in Use
If port 3000 is already in use, modify the port in `app.py`:
```python
app.run(host='0.0.0.0', port=3001, debug=True)
```

## What Changed from Node.js

1. **Server Framework**: Express.js → Flask
2. **ORM**: Sequelize → SQLAlchemy
3. **HTTP Client**: node-fetch → requests
4. **Package Manager**: npm → pip
5. **Dependencies**: package.json → requirements.txt
6. **Startup**: `node server.js` → `python app.py`

## Next Steps

1. Test all API endpoints
2. Update frontend to point to the new Python backend (if needed)
3. Migrate any remaining Node.js-specific logic
4. Test file uploads and downloads
5. Test YOLOX training functionality

## File Structure Comparison

**Before (Node.js):**
```
backend/
├── server.js
├── package.json
├── routes/api.js
├── models/*.js
└── services/*.js
```

**After (Python):**
```
backend/
├── app.py
├── requirements.txt
├── routes/api.py
├── models/*.py
└── services/*.py
```