AWS Lambda Typing

Warnings

• gotcha Older versions of `aws-lambda-typing` (prior to 2.17.1) might have incorrectly marked all fields in `APIGatewayProxyResponseV1` as required due to default `TypedDict` behavior, leading to static analysis errors if optional fields were omitted. Similarly, API Gateway event fields were made `Optional` in v2.16.4.
  Fix: Upgrade to `aws-lambda-typing` version 2.17.1 or newer. For older versions, manually annotate potentially missing fields as `Optional[type]`.
• gotcha The structure of AWS Lambda event objects frequently evolves. Using an outdated version of `aws-lambda-typing` may lead to missing or incorrect type definitions for newer event structures, causing type checker warnings or runtime `KeyError` if types are used for validation.
  Fix: Regularly update `aws-lambda-typing` to its latest version to ensure compatibility with the most current AWS Lambda event schemas. Consult the GitHub releases for changes related to specific event types.
• gotcha While `aws-lambda-typing` provides robust types for Lambda events and context, it does not include types for `boto3` service responses. Mixing `boto3` response structures directly with `aws-lambda-typing` event types can lead to type mismatches.
  Fix: Use dedicated typing solutions like `types-boto3` or generate service-specific types for `boto3` responses if strict type checking is desired for AWS SDK interactions within your Lambda functions. Keep a clear separation between event/context types and service client response types.

Install

• pip install aws-lambda-typing Install latest version

Imports

• Context

  from aws_lambda_typing.context import Context

• APIGatewayProxyEventV2

  from aws_lambda_typing.events.api_gateway import APIGatewayProxyEventV2

• SQSEvent

  from aws_lambda_typing.events.sqs import SQSEvent

• APIGatewayProxyResponseV2

  from aws_lambda_typing.responses.api_gateway import APIGatewayProxyResponseV2

• APIGatewayProxyEventV1

  from aws_lambda_typing.events.api_gateway import APIGatewayProxyEventV1

  While older versions might have allowed direct import from `events`, specific event types are now organized into submodules for better clarity and maintainability.

Quickstart

This quickstart demonstrates a basic AWS Lambda handler using type hints for an API Gateway HTTP API (v2) event and context object, and specifies the expected response type. It illustrates how to access common event fields and context attributes with IDE assistance.

import os
from aws_lambda_typing.context import Context
from aws_lambda_typing.events.api_gateway import APIGatewayProxyEventV2
from aws_lambda_typing.responses.api_gateway import APIGatewayProxyResponseV2

def lambda_handler(
    event: APIGatewayProxyEventV2,
    context: Context
) -> APIGatewayProxyResponseV2:
    path = event.get('requestContext', {}).get('http', {}).get('path', '/')
    method = event.get('requestContext', {}).get('http', {}).get('method', 'GET')
    query_params = event.get('queryStringParameters', {})

    print(f"Received {method} request for {path} with query params: {query_params}")

    # Example of accessing context object
    print(f"Lambda function name: {context.function_name}")

    return {
        'statusCode': 200,
        'headers': {'Content-Type': 'application/json'},
        'body': '{"message": "Hello from typed Lambda!"}'
    }