How-To Guides¶
Practical step-by-step guides for common tasks with pico-fastapi.
Available Guides¶
| Guide | Description |
|---|---|
| Migrating from FastAPI | Coming from vanilla FastAPI? Depends() to constructors, routers to controllers |
| Session Shopping Cart | Implement session-scoped state with a shopping cart |
| Apply Settings | Configure FastAPI app from YAML/environment |
| WebSocket Chat | Build a real-time chat with WebSocket support |
| CORS Middleware | Add CORS middleware using FastApiConfigurer |
| WebSocket Controllers | Create WebSocket controllers with proper scope |
| Testing Controllers | Test controllers with TestClient, mocks, and overrides |
Quick Reference¶
Adding Middleware¶
from pico_ioc import component
from pico_fastapi import FastApiConfigurer
from fastapi import FastAPI
@component
class MyMiddlewareConfigurer(FastApiConfigurer):
priority = -10 # Negative = outer middleware
def configure_app(self, app: FastAPI) -> None:
app.add_middleware(MyMiddleware)
Creating a Controller¶
from pico_fastapi import controller, get, post
@controller(prefix="/api/items", tags=["Items"])
class ItemController:
def __init__(self, service: ItemService):
self.service = service
@get("/")
async def list_items(self):
return self.service.list_all()
@post("/")
async def create_item(self, data: ItemCreate):
return self.service.create(data)
WebSocket Endpoint¶
from pico_fastapi import controller, websocket
from fastapi import WebSocket
@controller(scope="websocket")
class WsController:
@websocket("/ws")
async def ws_endpoint(self, websocket: WebSocket):
await websocket.accept()
while True:
data = await websocket.receive_text()
await websocket.send_text(f"Echo: {data}")
Testing with Mocks¶
from pico_boot import init
from fastapi import FastAPI
from fastapi.testclient import TestClient
def test_endpoint():
container = init(
modules=["myapp"],
overrides={RealService: MockService()},
)
app = container.get(FastAPI)
with TestClient(app) as client:
response = client.get("/api/items")
assert response.status_code == 200