PythonBeginner8 min read2026-03-01

Build REST API with FastAPI

Create high-performance, asynchronous REST APIs with Python 3, FastAPI, Pydantic, and Uvicorn.

Prerequisites

Python 3.10+ installed
Basic understanding of Python functions and types

1. Installation and Basic Setup

Install FastAPI and the Uvicorn ASGI server.

2. Defining Data Models and Endpoints

Use Pydantic for automatic data validation, serialization, and interactive Swagger docs.

python

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
from typing import List

app = FastAPI(title="DevFixHub API")

class BugReport(BaseModel):
    id: int
    title: str
    resolved: bool = False

bugs_db: List[BugReport] = []

@app.get("/bugs", response_model=List[BugReport])
async def get_bugs():
    return bugs_db

@app.post("/bugs", response_model=BugReport, status_code=201)
async def create_bug(bug: BugReport):
    bugs_db.append(bug)
    return bug

Best Practices & Architecture Advice

Always define explicit response_model in route decorators for automatic schema documentation and output filtering.
Use async def only for operations that perform non-blocking I/O (database or network calls).

Common Mistakes to Watch Out For

•Using blocking libraries (like time.sleep() or requests) inside async def routes, which blocks the event loop.

Frequently Asked Questions

Where can I view the auto-generated documentation?

Visit http://localhost:8000/docs for Swagger UI or http://localhost:8000/redoc for ReDoc.