DEV Community

A0mineTV
A0mineTV

Posted on

🚀 Building a User Management API with FastAPI and SQLite

#fastapi #python #sqlite #api

FastAPI has become one of the most popular Python web frameworks, thanks to its speed, simplicity, and intuitive design. In this article, we’ll build a User Management API using FastAPI and SQLite. The API will include features like creating, retrieving, updating, and deleting users (CRUD).

Let’s dive in! 🏊‍♂️

🏗 Prerequisites

Before we start, ensure you have the following installed:

  • Python 3.8+
  • pip (Python package manager)

Install FastAPI and the ASGI server Uvicorn:

pip install fastapi uvicorn sqlalchemy pydantic
Enter fullscreen mode Exit fullscreen mode

📜 The Project Structure

Here’s what we’ll build:

  1. SQLite Database: Store user data using SQLAlchemy.
  2. CRUD Operations: Endpoints to manage users.
  3. Validation: Ensure correct data is provided using Pydantic.

🛠 Code Implementation

1️⃣ Database Setup with SQLAlchemy

Start by defining the database connection and user model:

from sqlalchemy import Column, Integer, String, create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm import sessionmaker DATABASE_URL = "sqlite:///./users.db" engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False}) Base = declarative_base() SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine) # User model for SQLAlchemy class User(Base): __tablename__ = "users" id = Column(Integer, primary_key=True, index=True) name = Column(String, index=True, nullable=False) email = Column(String, unique=True, index=True, nullable=False) age = Column(Integer, nullable=False) # Create the database table Base.metadata.create_all(bind=engine)
Enter fullscreen mode Exit fullscreen mode

2️⃣ FastAPI App Initialization

Now, initialize your FastAPI application and define database session dependencies:

from fastapi import FastAPI, HTTPException, Depends from sqlalchemy.orm import Session app = FastAPI() def get_db(): db = SessionLocal() try: yield db finally: db.close()
Enter fullscreen mode Exit fullscreen mode

3️⃣ Define Pydantic Models

Pydantic is used for request validation and response formatting.

from pydantic import BaseModel class UserCreate(BaseModel): name: str email: str age: int class UserResponse(BaseModel): id: int name: str email: str age: int class Config: orm_mode = True
Enter fullscreen mode Exit fullscreen mode

4️⃣ CRUD Endpoints

Let’s implement the core features of our User Management API.

Create a New User

@app.post("/users/", response_model=UserResponse) def create_user(user: UserCreate, db: Session = Depends(get_db)): db_user = db.query(User).filter(User.email == user.email).first() if db_user: raise HTTPException(status_code=400, detail="Email already registered") new_user = User(name=user.name, email=user.email, age=user.age) db.add(new_user) db.commit() db.refresh(new_user) return new_user
Enter fullscreen mode Exit fullscreen mode

Retrieve All Users

@app.get("/users/", response_model=list[UserResponse]) def get_users(db: Session = Depends(get_db)): return db.query(User).all()
Enter fullscreen mode Exit fullscreen mode

Update a User by ID

@app.put("/users/{user_id}", response_model=UserResponse) def update_user(user_id: int, user: UserCreate, db: Session = Depends(get_db)): db_user = db.query(User).filter(User.id == user_id).first() if not db_user: raise HTTPException(status_code=404, detail="User not found") db_user.name = user.name db_user.email = user.email db_user.age = user.age db.commit() db.refresh(db_user) return db_user
Enter fullscreen mode Exit fullscreen mode

Delete a User by ID

@app.delete("/users/{user_id}") def delete_user(user_id: int, db: Session = Depends(get_db)): db_user = db.query(User).filter(User.id == user_id).first() if not db_user: raise HTTPException(status_code=404, detail="User not found") db.delete(db_user) db.commit() return {"message": "User deleted successfully"}
Enter fullscreen mode Exit fullscreen mode

5️⃣ Run the Application

Run your application using Uvicorn:

uvicorn main:app --reload
Enter fullscreen mode Exit fullscreen mode

Visit http://127.0.0.1:8000/docs to explore your API with the automatically generated Swagger UI.

🎯 Testing the API

Here are some examples to interact with the API:

  1. Create a User: 
 curl -X POST "http://127.0.0.1:8000/users/" \ -H "Content-Type: application/json" \ -d '{"name": "John Doe", "email": "john@example.com", "age": 30}'
Enter fullscreen mode Exit fullscreen mode
  1. Get All Users: 
 curl -X GET "http://127.0.0.1:8000/users/"
Enter fullscreen mode Exit fullscreen mode
  1. Update a User: 
 curl -X PUT "http://127.0.0.1:8000/users/1" \ -H "Content-Type: application/json" \ -d '{"name": "Jane Doe", "email": "jane@example.com", "age": 25}'
Enter fullscreen mode Exit fullscreen mode
  1. Delete a User: 
 curl -X DELETE "http://127.0.0.1:8000/users/1"
Enter fullscreen mode Exit fullscreen mode

🌟 Key Features of This Example

  1. FastAPI's Speed and Simplicity:

    • FastAPI automatically validates data and generates interactive documentation.

  2. SQLAlchemy Integration:

    • SQLAlchemy makes database management seamless with its ORM.

  3. Type Safety:

    • Pydantic ensures all input and output data types are validated.

🚀 Wrapping Up

This example demonstrates how easily you can build a scalable and efficient API with FastAPI. With its developer-friendly design, built-in validation, and performance, FastAPI is an excellent choice for modern Python web applications.

What feature would you add to this API? Let me know in the comments! 🎉

Happy coding! 👨‍💻👩‍💻

Top comments (0)