docs: add docs for data classes utility

Author: Tom McCarthy

docs/content/index.mdx

@@ -30,6 +30,7 @@ sam init --location https://github.com/aws-samples/cookiecutter-aws-sam-python
 * [Bring your own middleware](./utilities/middleware_factory) - Decorator factory to create your own middleware to run logic before, and after each Lambda invocation
 * [Parameters utility](./utilities/parameters) - Retrieve parameter values from AWS Systems Manager Parameter Store, AWS Secrets Manager, or Amazon DynamoDB, and cache them for a specific amount of time
 * [Batch utility](./utilities/batch) - Batch processing for AWS SQS, handles partial failure.
+* [Event source data classes](./utilities/data_classes) - Batch processing for AWS SQS, handles partial failure.
 
 ### Lambda Layer
 
@@ -73,6 +74,7 @@ Utility | Description
 [Bring your own middleware](.//utilities/middleware_factory) | Decorator factory to create your own middleware to run logic before, and after each Lambda invocation
 [Parameters utility](./utilities/parameters) | Retrieve parameter values from AWS Systems Manager Parameter Store, AWS Secrets Manager, or Amazon DynamoDB, and cache them for a specific amount of time
 [Typing utility](./utilities/typing) | Static typing classes to speedup development in your IDE
+[Event source data classes](./utilities/data_classes) - Batch processing for AWS SQS, handles partial failure.
 
 ## Environment variables
 

docs/content/media/utilities_data_classes.png

@@ -0,0 +1,210 @@
+---
+title: Event Source Data Classes
+description: Utility
+---
+
+import Note from "../../src/components/Note"
+
+The event source data classes utility provides classes describing the schema of common trigger Lambda events triggers.
+
+**Key Features**
+
+* Type hinting and code completion for common event types
+* Helper functions for decoding/deserializing nested fields
+* Docstrings for fields contained in event schemas
+
+**Background**
+
+When authoring Lambda functions, you often need to understand the schema of the event dictionary which is passed to the
+handler. There are several common event types which follow a specific schema, depending on the service triggering the
+Lambda function.
+
+
+## Utilizing the data classes
+
+The classes are initialized by passing in the Lambda event object into the constructor of the appropriate data class.
+For example, if your Lambda function is being triggered by an API Gateway proxy integration, you can use the
+`APIGatewayProxyEvent` class.
+
+![Utilities Data Classes](../media/utilities_data_classes.png)
+
+
+## Supported event sources
+<Note type="info">
+    The examples provided below are far from exhaustive - the data classes themselves are designed to provide a form of
+    documentation inherently (via autocompletion, types and docstrings).
+</Note>
+
+
+### API Gateway Proxy V1 (REST API)
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import APIGatewayProxyEvent
+
+def lambda_handler(event, context):
+    event = APIGatewayProxyEvent(event)
+    request_context = event.request_context
+    identity = request_context.identity
+
+    if 'helloworld' in event.path && event.http_method == 'GET':
+        user = identity.user
+        do_something_with(event.body, user)
+```
+
+### API Gateway Proxy V2 (HTTP API)
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import APIGatewayProxyEventV2
+
+def lambda_handler(event, context):
+    event = APIGatewayProxyEventV2(event)
+    request_context = event.request_context
+    query_string_parameters = event.query_string_parameters
+
+    if 'helloworld' in event.raw_path && request_context.http.method == 'POST':
+        do_something_with(event.body, query_string_parameters)
+```
+
+### CloudWatch logs
+CloudWatch logs events by default are compressed and base64 encoded. You can use the helper function provided to decode,
+decompress and parse json data from the event.
+
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import CloudWatchLogsEvent
+
+def lambda_handler(event, context):
+    event = CloudWatchLogsEvent(event)
+
+    decompressed_log = event.parse_logs_data
+    log_events = decompressed_log.log_events
+    for event in log_events:
+        do_something_with(event.timestamp, event.message)
+```
+
+### Cognito user pool triggers
+Cognito User Pools have several [different Lambda trigger sources](https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-identity-pools-working-with-aws-lambda-triggers.html#cognito-user-identity-pools-working-with-aws-lambda-trigger-sources), all of which map to a different data class, which
+can be imported from `aws_lambda_powertools.data_classes.cognito_user_pool_event`:
+
+Trigger/Event Source | Data Class
+------------------------------------------------- | -------------------------------------------------
+Custom message event | `data_classes.cognito_user_pool_event.CustomMessageTriggerEvent`
+Post authentication | `data_classes.cognito_user_pool_event.PostAuthenticationTriggerEvent`
+Post confirmation | `data_classes.cognito_user_pool_event.PostConfirmationTriggerEvent`
+Pre authentication | `data_classes.cognito_user_pool_event.PreAuthenticationTriggerEvent`
+Pre sign-up | `data_classes.cognito_user_pool_event.PreSignUpTriggerEvent`
+Pre token generation | `data_classes.cognito_user_pool_event.PreTokenGenerationTriggerEvent`
+User migration | `data_classes.cognito_user_pool_event.UserMigrationTriggerEvent`
+
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.cognito_user_pool_event import PostConfirmationTriggerEvent
+
+def lambda_handler(event, context):
+    event = PostConfirmationTriggerEvent(event)
+
+    user_attributes = user_attributes = event.request.user_attributes
+    do_something_with(user_attributes)
+```
+
+### DynamoDB streams
+The DynamoDB data class utility provides the base class for `DynamoDBStreamEvent`, a typed class for
+attributes values (`AttributeValue`), as well as enums for stream view type (`StreamViewType`) and event type
+(`DynamoDBRecordEventName`).
+
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import DynamoDBStreamEvent, StreamViewType
+
+def lambda_handler(event, context):
+    event = DynamoDBStreamEvent(event)
+
+    # Multiple records can be delivered in a single event
+    for record in event.records:
+        if record.event_name == DynamoDBRecordEventName.MODIFY:
+            do_something_with(record.dynamodb.new_image)
+            do_something_with(record.dynamodb.old_image)
+```
+
+### EventBridge
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import EventBridgeEvent
+
+def lambda_handler(event, context):
+    event = EventBridgeEvent(event)
+    do_something_with(event.detail)
+
+```
+
+### Kinesis streams
+Kinesis events by default contain base64 encoded data. You can use the helper function to access the data either as json
+or plain text, depending on the original payload.
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import KinesisStreamEvent
+
+def lambda_handler(event, context):
+    event = KinesisStreamEvent(event)
+
+    # if data was delivered as json
+    data = event.data_as_text()
+
+    # if data was delivered as text
+    data = event.data_as_json()
+
+    do_something_with(data)
+
+```
+
+### S3 events
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import S3Event
+
+def lambda_handler(event, context):
+    event = S3Event(event)
+    bucket_name = event.bucket_name
+
+    # Multiple records can be delivered in a single event
+    for record in event.records:
+        object_key = record.s3.get_object.key
+
+        do_something_with(f'{bucket_name}/{object_key}')
+
+```
+
+### SES events
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import SESEvent
+
+def lambda_handler(event, context):
+    event = SESEvent(event)
+
+    # Multiple records can be delivered in a single event
+    for record in event.records:
+        mail = record.ses.mail
+        common_headers = list(mail.common_headers)
+
+        do_something_with(common_headers.to, common_headers.subject)
+
+```
+
+### SNS
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import SNSEvent
+
+def lambda_handler(event, context):
+    event = SNSEvent(event)
+
+    # Multiple records can be delivered in a single event
+    for record in event.records:
+        message = record.sns.message
+        subject = record.sns.subject
+
+        do_something_with(subject, message)
+```
+
+### SQS
+```python:title=lambda_app.py
+from aws_lambda_powertools.utilities.data_classes import SQSEvent
+
+def lambda_handler(event, context):
+    event = SQSEvent(event)
+
+    # Multiple records can be delivered in a single event
+    for record in event.records:
+        do_something_with(record.body)
+```

docs/content/utilities/data_classes.mdx

@@ -34,7 +34,8 @@ module.exports = {
                         'utilities/parameters',
                         'utilities/batch',
                         'utilities/typing',
-                        'utilities/validation'
+                        'utilities/validation',
+                        'utilities/data_classes'
                     ],
                 },
                 navConfig: {