https://github.com/ysocrius/django-credit-approval

Django-based REST API for automated credit approval and loan management with PostgreSQL, Redis, Celery, and Docker. Features credit score calculation, loan eligibility assessment, interest rate correction, and comprehensive API documentation with Swagger/OpenAPI integration.
https://github.com/ysocrius/django-credit-approval

api-documentation banking celery containerization credit-approval credit-scoring django django-rest-framework docker docker-compose financial-services fintech loan-management postgresql python redis rest-api risk-assessment swagger-ui unit-testing

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Django-based REST API for automated credit approval and loan management with PostgreSQL, Redis, Celery, and Docker. Features credit score calculation, loan eligibility assessment, interest rate correction, and comprehensive API documentation with Swagger/OpenAPI integration.

• Host: GitHub
• URL: https://github.com/ysocrius/django-credit-approval
• Owner: ysocrius
• Created: 2025-09-13T08:15:47.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2026-01-24T21:42:45.000Z (5 months ago)
• Last Synced: 2026-01-25T09:59:14.392Z (5 months ago)
• Topics: api-documentation, banking, celery, containerization, credit-approval, credit-scoring, django, django-rest-framework, docker, docker-compose, financial-services, fintech, loan-management, postgresql, python, redis, rest-api, risk-assessment, swagger-ui, unit-testing
• Language: Python
• Size: 509 KB
• Stars: 0
• Watchers: 0
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# Credit Approval System

A simple Django-based REST API for managing customer loans and credit approvals.

## Features

- Customer registration with automatic credit limit calculation

- Credit score-based loan eligibility checking

- Loan creation with interest rate correction

- View loan details and active loans

- Background data ingestion from Excel files

## Demo

### 1. Customer Registration

![Register Customer](docs/screenshots/register_form.png)

*Registration Form with Validation*

![Registration Success](docs/screenshots/register_success.png)

*Successful Registration Check*

### 2. Check Eligibility

![Loan Eligibility](docs/screenshots/eligibility_approved.png)

*Loan Eligibility Check & Approval*

### 3. View Loans Dashboard

![View Loans](docs/screenshots/view_loans.png)

*Customer Loan Dashboard*

## Tech Stack

### Backend

- Django 4.2+

- Django REST Framework

- PostgreSQL

- Redis

- Celery

- Docker & Docker Compose

### Frontend (Optional)

- React 18 + TypeScript

- Tailwind CSS

- React Query

- React Hook Form + Zod

- Vite

## Quick Start

### Prerequisites

- Docker Desktop installed and running

- Git installed

- Excel files (`customer_data.xlsx` and `loan_data.xlsx`) for data ingestion (optional)

### Running the Application

1. **Clone the repository**

   ```bash

   git clone https://github.com/ysocrius/django-credit-approval.git

   cd django-credit-approval

   ```

2. **Set up environment variables**

   ```bash

   # Copy the example environment file

   cp .env.example .env

   

   # Edit .env file if needed (default values work for development)

   # For production, use .env.prod.example as template

   ```

3. **Place Excel files (if available)**

   - Copy `customer_data.xlsx` and `loan_data.xlsx` to the `data/` directory

   - See `data/README.md` for file format specifications

4. **Start all services**

   ```bash

   docker compose up --build -d

   ```

   Note: Migrations run automatically on startup.

5. **Load initial data from Excel files (if available)**

   

   Option 1: Using management command (recommended)

   ```bash

   # Async via Celery (default)

   docker compose exec web python manage.py ingest_data

   

   # Or synchronously if Celery is not available

   docker compose exec web python manage.py ingest_data --sync

   ```

   

   Option 2: Using Django shell

   ```bash

   docker compose exec web python manage.py shell

   >>> from api.tasks import ingest_data

   >>> ingest_data.delay()  # Async

   # OR

   >>> ingest_data()  # Sync

   ```

## Frontend Application

A modern React frontend is available for the Credit Approval System.

### Access Frontend

- **URL**: `http://localhost:3000`

- Available when running with Docker Compose

### Frontend Features

- ✅ Customer Registration Form

- ✅ Loan Eligibility Checker

- ✅ Loan Creation Interface

- ✅ Customer Loans Dashboard

- ✅ Real-time API Integration

- ✅ Form Validation

- ✅ Responsive Design

### Running Frontend Locally (Development)

```bash

cd frontend

npm install

npm run dev

```

See `frontend/README.md` for detailed frontend documentation.

## API Documentation

### Swagger/OpenAPI Documentation

Interactive API documentation is available at:

- Swagger UI: `http://localhost:8000/swagger/` or `http://localhost:8000/`

- ReDoc: `http://localhost:8000/redoc/`

- OpenAPI Schema: `http://localhost:8000/swagger.json`

## API Endpoints

### 1. Register Customer

- **URL**: `/register`

- **Method**: POST

- **Body**:

  ```json

  {

    "first_name": "John",

    "last_name": "Doe",

    "age": 30,

    "monthly_income": 50000,

    "phone_number": "9876543210"

  }

  ```

### 2. Check Loan Eligibility

- **URL**: `/check-eligibility`

- **Method**: POST

- **Body**:

  ```json

  {

    "customer_id": 1,

    "loan_amount": 500000,

    "interest_rate": 10.5,

    "tenure": 24

  }

  ```

### 3. Create Loan

- **URL**: `/create-loan`

- **Method**: POST

- **Body**:

  ```json

  {

    "customer_id": 1,

    "loan_amount": 500000,

    "interest_rate": 10.5,

    "tenure": 24

  }

  ```

### 4. View Loan Details

- **URL**: `/view-loan/`

- **Method**: GET

### 5. View Customer's Active Loans

- **URL**: `/view-loans/`

- **Method**: GET

### 6. Health Check Endpoints

- **Basic Health**: `/health/` - Simple health status

- **Detailed Health**: `/health/detailed/` - Checks all dependencies (DB, Redis, Celery)

- **Readiness Check**: `/health/ready/` - Kubernetes readiness probe

- **Liveness Check**: `/health/live/` - Kubernetes liveness probe

## Business Logic

### Credit Score Calculation

- Base score: 50 points

- On-time payments: +30 points maximum

- Recent loans: -5 points per loan in current year

- If current debt > approved limit: score = 0

### Loan Approval Rules

- If credit_rating > 50: Approve loan with any interest rate

- If 50 > credit_rating > 30: Approve loans with interest rate > 12%

- If 30 > credit_rating > 10: Approve loans with interest rate > 16%

- If 10 > credit_rating: Don't approve any loans

- If sum of all current EMIs > 50% of monthly salary: Don't approve any loans

### EMI Calculation

Uses compound interest formula:

```

EMI = P × r × (1+r)^n / ((1+r)^n - 1)

```

Where:

- P = Principal amount

- r = Monthly interest rate

- n = Number of months

## Stopping the Application

```bash

docker compose down

```

## Running Tests

```bash

# Run all unit tests

docker compose exec web python manage.py test

# Run specific test modules

docker compose exec web python manage.py test api.tests.HelpersTestCase

docker compose exec web python manage.py test api.tests.ApiEndpointsTestCase

```

## Viewing Logs

```bash

# Django logs

docker compose logs web

# Celery worker logs

docker compose logs worker

# Database logs

docker compose logs db

# Follow logs in real-time

docker compose logs -f web worker

```

## Testing

### Unit Tests

```bash

# Run all tests

docker compose exec web python manage.py test

# Run with coverage

docker compose exec web coverage run --source='.' manage.py test

docker compose exec web coverage report

```

### API Testing with Postman

1. Import `Credit_Approval_API.postman_collection.json` into Postman

2. Set the `base_url` variable to `http://localhost:8000`

3. Run the collection to test all endpoints

## Production Deployment

### Using Production Configuration

```bash

# Copy production environment template

cp .env.prod.example .env.prod

# Edit .env.prod with your production values

vim .env.prod

# Start production services

docker compose -f docker-compose.prod.yml up -d

```

### Database Management

#### Backup Database

```bash

# Development environment

./scripts/backup_db.sh

# Production environment

./scripts/backup_db.sh prod

```

#### Restore Database

```bash

# Restore from backup

./scripts/restore_db.sh ./backups/backup_dev_credit_approval_db_20240101_120000.sql.gz

```

## CI/CD Pipeline

The project includes GitHub Actions workflow that automatically:

- Runs unit tests on every push/PR

- Checks code formatting with Black

- Validates imports with isort

- Performs security checks with Bandit

- Builds and tests Docker images

- Generates test coverage reports

## Recent Improvements

### Testing

- ✅ Comprehensive test coverage for all business rules

- ✅ Edge case testing (boundary values, invalid inputs)

- ✅ Concurrent loan creation testing

- ✅ Credit score component testing

- ✅ Interest rate correction validation

### API Documentation

- ✅ Swagger/OpenAPI integration with drf-yasg

- ✅ Interactive API testing interface

- ✅ Auto-generated API documentation

### Data Validation

- ✅ Enhanced input validation with detailed error messages

- ✅ Name validation (letters only)

- ✅ Phone number sanitization

- ✅ Cross-field validation for loans

- ✅ Boundary value checks

### Monitoring & Health

- ✅ Comprehensive logging configuration

- ✅ Health check endpoints for all services

- ✅ Kubernetes-ready health probes

- ✅ Service dependency monitoring

### Docker Optimization

- ✅ Multi-stage build for smaller images

- ✅ Non-root user for security

- ✅ Health checks for all containers

- ✅ Optimized dependency caching

- ✅ Log volume persistence

### Security

- ✅ Non-root container execution

- ✅ Input sanitization

- ✅ Environment variable configuration

- ✅ Secure defaults