17. CRUD Operations with MongoDB

MongoDB Local Setup (Ubuntu, macOS, Windows)

FastAPI relies on an external database service, and MongoDB must be installed and running locally before integration. MongoDB runs as a background service and exposes a local endpoint, typically on port 27017. A consistent local setup ensures predictable development and debugging across operating systems.

Ubuntu

sudo apt update
sudo apt install -y mongodb
sudo systemctl start mongodb
sudo systemctl enable mongodb

macOS (Homebrew)

brew tap mongodb/brew
brew install mongodb-community
brew services start mongodb-community

Windows Install MongoDB Community Server from the official MongoDB installer and run it as a Windows Service or start it using MongoDB Compass.

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Connecting FastAPI with MongoDB

FastAPI commonly integrates with MongoDB using an asynchronous driver to align with non-blocking request handling. A single database client is created and reused across requests to avoid connection overhead. This setup forms the foundation for all CRUD operations.

from motor.motor_asyncio import AsyncIOMotorClient

client = AsyncIOMotorClient("mongodb://localhost:27017")
db = client["tourism_db"]
tourist_collection = db["tourists"]

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Implementing Create, Read, Update, Delete Operations

CRUD operations map directly to MongoDB commands and HTTP semantics. FastAPI routes expose these operations in a clear and predictable manner, making data access explicit and traceable. Each operation represents a well-defined interaction with the database.

from fastapi import FastAPI

app = FastAPI()

@app.post("/tourists")
async def create_tourist(tourist: dict):
    await tourist_collection.insert_one(tourist)
    return tourist

@app.get("/tourists")
async def list_tourists():
    return await tourist_collection.find().to_list(100)

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Handling Schema Validation and Database Consistency

MongoDB allows flexible document structures, which places responsibility for data correctness on the application. FastAPI uses Pydantic models to validate input before persistence. This ensures consistent data while retaining MongoDB’s schema flexibility.

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Testing CRUD Endpoints Using cURL

cURL commands provide a simple and reproducible way to test FastAPI endpoints without additional tooling. These commands simulate real client behavior and are useful for debugging and documentation.

Create a Tourist

curl -X POST http://127.0.0.1:8000/tourists \
  -H "Content-Type: application/json" \
  -d '{
        "name": "Alice",
        "country": "Germany",
        "age": 32,
        "budget": 2500
      }'

Create Another Tourist

curl -X POST http://127.0.0.1:8000/tourists \
  -H "Content-Type: application/json" \
  -d '{
        "name": "Marco",
        "country": "Italy",
        "age": 41,
        "budget": 3200
      }'

List All Tourists

curl -X GET http://127.0.0.1:8000/tourists

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Operational Perspective

CRUD endpoints form the backbone of most data-driven FastAPI applications. When combined with proper validation, clear HTTP semantics, and reproducible testing via cURL, they provide a reliable foundation for more advanced features such as relationships, analytics, and reporting.