InventoryProject

Simple Inventory + Billing CRUD API built with Python, FastAPI, and MongoDB.

Features

• CRUD operations for 5 MongoDB collections: suppliers, products, customers, invoices, invoice_items
• Billing endpoint to create an invoice from product line items
• Automatic stock deduction during billing
• Basic duplicate protections with MongoDB indexes

Tech Stack

• Python
• FastAPI
• PyMongo
• MongoDB

Project Structure

.
├── app
│   ├── __init__.py
│   ├── config.py
│   ├── database.py
│   ├── main.py
│   ├── schemas.py
│   └── utils.py
├── .env.example
├── .gitignore
├── README.md
└── requirements.txt

Setup

1. Create and activate a virtual environment:

python3 -m venv .venv
source .venv/bin/activate

2. Install dependencies:

pip install -r requirements.txt

3. Copy environment file and edit values if needed:

cp .env.example .env

4. Ensure MongoDB is running (default URI in .env.example):

mongodb://localhost:27017

5. Run API server:

uvicorn app.main:app --reload

6. Open docs:

• Swagger UI: http://127.0.0.1:8000/docs
• ReDoc: http://127.0.0.1:8000/redoc

API Endpoints

Suppliers

• POST /suppliers
• GET /suppliers
• GET /suppliers/{supplier_id}
• PUT /suppliers/{supplier_id}
• DELETE /suppliers/{supplier_id}

Products

• POST /products
• GET /products
• GET /products/{product_id}
• PUT /products/{product_id}
• DELETE /products/{product_id}

Customers

• POST /customers
• GET /customers
• GET /customers/{customer_id}
• PUT /customers/{customer_id}
• DELETE /customers/{customer_id}

Invoices

• POST /invoices
• GET /invoices
• GET /invoices/{invoice_id}
• PUT /invoices/{invoice_id}
• DELETE /invoices/{invoice_id}

Invoice Items

• POST /invoice-items
• GET /invoice-items
• GET /invoice-items/{invoice_item_id}
• PUT /invoice-items/{invoice_item_id}
• DELETE /invoice-items/{invoice_item_id}

Billing Workflow

• POST /billing/invoices

Creates an invoice from product lines, inserts invoice items, and decreases stock.

Example Billing Request

curl -X POST "http://127.0.0.1:8000/billing/invoices" \
	-H "Content-Type: application/json" \
	-d '{
		"customer_id": "CUSTOMER_OBJECT_ID",
		"tax_rate": 0.05,
		"items": [
			{"product_id": "PRODUCT_OBJECT_ID_1", "quantity": 2},
			{"product_id": "PRODUCT_OBJECT_ID_2", "quantity": 1}
		]
	}'

Notes

• MongoDB uses collections, which are the equivalent of SQL tables.
• This project is intentionally simple and does not implement auth.