github aws-powertools/powertools-lambda-python v3.28.0
on GitHub

21 hours ago

Summary

This release brings dependency injection, an enriched Request object, OpenAPI improvements, and internal refactoring to the Event Handler.

  • Dependency injection: type-safe Depends() with nested resolution, caching, and test overrides
  • Enriched Request: resolved_event and context properties bridge middleware and dependencies
  • OpenAPI status_code: set default response status code on route decorators
  • Query string fix: parameters no longer dropped when both single and multi-value query strings are present

A huge thanks to @JustinBerger, @Iamrodos, and @ran-isenberg for their contributions!

Dependency injection with Depends()

Docs

You can now use Depends() to declare typed dependencies directly in route handler signatures: no decorators, no global state. Dependencies are resolved automatically, cached per invocation, and support nested dependency trees. 

import os
from typing import Any

import boto3
from typing_extensions import Annotated

from aws_lambda_powertools.event_handler import APIGatewayHttpResolver
from aws_lambda_powertools.event_handler.depends import Depends
from aws_lambda_powertools.utilities.typing import LambdaContext

app = APIGatewayHttpResolver()


def get_dynamodb_table():
    dynamodb = boto3.resource("dynamodb")
    return dynamodb.Table(os.environ["TABLE_NAME"])


@app.get("/orders")
def list_orders(table: Annotated[Any, Depends(get_dynamodb_table)]):
    return table.scan()["Items"]

For testing, swap any dependency without monkeypatching: 

app.dependency_overrides[get_dynamodb_table] = lambda: mock_table

Enriched Request object

Docs

The Request object now exposes resolved_event and context, enabling dependency functions to access the full Powertools event and bridge data with middleware. 

from typing_extensions import Annotated

from aws_lambda_powertools.event_handler import APIGatewayHttpResolver, Response
from aws_lambda_powertools.event_handler.depends import Depends
from aws_lambda_powertools.event_handler.request import Request

app = APIGatewayHttpResolver()


# Middleware handles auth: can return HTTP responses (redirects, 401s)
def auth_middleware(app, next_middleware):
    token = app.current_event.headers.get("authorization", "")
    if not token:
        return Response(status_code=401, body="Unauthorized")

    app.append_context(user={"id": "user-123", "role": "admin"})
    return next_middleware(app)


app.use(middlewares=[auth_middleware])


# Depends() reads what middleware wrote via request.context
def get_current_user(request: Request) -> dict:
    return request.context["user"]


@app.get("/admin/dashboard")
def admin_dashboard(user: Annotated[dict, Depends(get_current_user)]):
    return {"message": f"Welcome {user['id']}", "role": user["role"]}

OpenAPI status_code field

Docs

You can now set the default response status code directly on route decorators. This is reflected in the generated OpenAPI schema and Swagger UI. 

from aws_lambda_powertools.event_handler import APIGatewayRestResolver

app = APIGatewayRestResolver(enable_validation=True)


@app.post(
    "/todos",
    summary="Creates a new todo item",
    status_code=201,
    tags=["Todos"],
)
def create_todo(title: str) -> dict:
    return {"id": 1, "title": title}

Changes

📜 Documentation updates

🔧 Maintenance

This release was made possible by the following contributors:

@JustinBerger, @dependabot[bot], @github-actions[bot], @leandrodamascena, dependabot[bot] and github-actions[bot]

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