Overview

Flask 2.0, released on May 12, 2021, is a major release that introduces async view support and nested blueprints.

Main Features

Async views

Flask 2.0 natively supports async view functions. Handlers can use await for non-blocking I/O operations without leaving the Flask ecosystem.

python 
from flask import Flask
import httpx

app = Flask(__name__)

@app.get('/weather/<city>')
async def weather(city):
    async with httpx.AsyncClient() as client:
        resp = await client.get(
            f'https://api.weather.example/{city}'
        )
        return resp.json()

@app.get('/health')
async def health():
    return {'status': 'ok'}

Nested blueprints

Blueprints can now be nested, allowing you to structure an application into hierarchical modules with composed URL prefixes.

python 
from flask import Flask, Blueprint

# Parent blueprint
api = Blueprint('api', __name__, url_prefix='/api')

# Child blueprint
users = Blueprint('users', __name__, url_prefix='/users')

@users.get('/')
def listing():
    return {'users': []}

# Nesting
api.register_blueprint(users)

app = Flask(__name__)
app.register_blueprint(api)
# Final route: /api/users/

Sources