Mastering FastAPI: Organizing Bigger Applications with Multiple Files for a Seamless User Experience
FastAPI has rapidly become a popular choice among web developers for its simplicity, performance, and ease of use. As your application grows, maintaining a clean and organized codebase becomes crucial. In this blog post, we’ll explore best practices for structuring larger FastAPI applications using multiple files, ensuring a seamless user experience.
Why Organize Your FastAPI Application?
Organizing your FastAPI application into multiple files is essential for several reasons:
- Readability: A well-structured codebase is easier to navigate and understand.
- Maintainability: Isolated components reduce complexity, making it simpler to update and debug code.
- Collaboration: A modular structure enables multiple developers to work on different parts of the application simultaneously.
Project Structure
A typical structure for a larger FastAPI application might look like this:
project_root/
├── app/
│ ├── __init__.py
│ ├── main.py
│ ├── routers/
│ │ ├── __init__.py
│ │ ├── users.py
│ │ ├── items.py
│ ├── models/
│ │ ├── __init__.py
│ │ ├── user.py
│ │ ├── item.py
│ ├── schemas/
│ │ ├── __init__.py
│ │ ├── user.py
│ │ ├── item.py
│ ├── databases.py
├── tests/
│ ├── __init__.py
│ ├── test_users.py
│ ├── test_items.py
├── requirements.txt
Each folder serves a specific purpose:
- app/: Contains the main application files.
- routers/: Holds the route logic (endpoints) split into different modules.
- models/: Contains the database models.
- schemas/: Defines the Pydantic models for data validation.
- databases.py: Sets up the database connection.
- tests/: Includes test cases for the application.
Setting Up the Main Application
Let’s start by setting up the main application file main.py:
from fastapi import FastAPI
from .routers import users, items
app = FastAPI()
app.include_router(users.router)
app.include_router(items.router)
This file initializes the FastAPI app and includes routers for users and items.
Creating Routers
Next, let’s create router files for our application. For example, here’s the users.py router:
from fastapi import APIRouter, Depends
from sqlalchemy.orm import Session
from .. import models, schemas, databases
router = APIRouter(prefix="/users", tags=["users"])
@router.post("/", response_model=schemas.User)
def create_user(user: schemas.UserCreate, db: Session = Depends(databases.get_db)):
db_user = models.User(name=user.name, email=user.email)
db.add(db_user)
db.commit()
db.refresh(db_user)
return db_user
This router handles user creation, using dependency injection for the database session.
Setting Up Models and Schemas
For database models, let’s define a simple user model in user.py:
from sqlalchemy import Column, Integer, String
from ..databases import Base
class User(Base):
__tablename__ = "users"
id = Column(Integer, primary_key=True, index=True)
name = Column(String, index=True)
email = Column(String, unique=True, index=True)
And here’s a Pydantic schema for user validation in user.py under schemas/:
from pydantic import BaseModel
class UserBase(BaseModel):
name: str
email: str
class UserCreate(UserBase):
pass
class User(UserBase):
id: int
class Config:
orm_mode = True
These schemas ensure data validity and serialization.
Database Configuration
Finally, set up the database connection in databases.py:
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
engine = create_engine(SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()
def get_db():
db = SessionLocal()
try:
yield db
finally:
db.close()
This configuration uses SQLite for simplicity but can be adapted for other databases.
Conclusion
In this post, we covered how to organize a larger FastAPI application into multiple files for better readability, maintainability, and collaboration. By structuring your application with clear separation of concerns, you can ensure a more scalable and manageable codebase. Start refactoring your FastAPI projects today to experience the benefits of a well-organized application!
Call to Action: Try reorganizing your existing FastAPI application following the structure outlined in this post. Share your experiences in the comments below!
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