Docs: Batch - creating a custom batch processor example has python syntax errors

[michaelbrewer]

Expected Behaviour

Example for Creating a custom batch processor should be validate and compile

Current Behaviour

success_handler is missing result

Code snippet

from random import randint

from aws_lambda_powertools.utilities.batch import BasePartialProcessor, batch_processor
import boto3
import os

table_name = os.getenv("TABLE_NAME", "table_not_found")

class MyPartialProcessor(BasePartialProcessor):
    """
    Process a record and stores successful results at a Amazon DynamoDB Table

    Parameters
    ----------
    table_name: str
        DynamoDB table name to write results to
    """

    def __init__(self, table_name: str):
        self.table_name = table_name

        super().__init__()

    def _prepare(self):
        # It's called once, *before* processing
        # Creates table resource and clean previous results
        self.ddb_table = boto3.resource("dynamodb").Table(self.table_name)
        self.success_messages.clear()

    def _clean(self):
        # It's called once, *after* closing processing all records (closing the context manager)
        # Here we're sending, at once, all successful messages to a ddb table
        with self.ddb_table.batch_writer() as batch:
            for result in self.success_messages:
                batch.put_item(Item=result)

    def _process_record(self, record):
        # It handles how your record is processed
        # Here we're keeping the status of each run
        # where self.handler is the record_handler function passed as an argument
        try:
            result = self.handler(record) # record_handler passed to decorator/context manager
            return self.success_handler(record, result)
        except Exception as exc:
            return self.failure_handler(record, exc)

    def success_handler(self, record):
        entry = ("success", result, record)
        message = {"age": result}
        self.success_messages.append(message)
        return entry


def record_handler(record):
    return randint(0, 100)

@batch_processor(record_handler=record_handler, processor=MyPartialProcessor(table_name))
def lambda_handler(event, context):
    return {"statusCode": 200}

Possible Solution

Fix the code example and ensure that it compiles, a PR for this already exists #1114 , a deployed fix is here : https://gyft.github.io/aws-lambda-powertools-python/latest/utilities/batch/#create-your-own-partial-processor

from random import randint

from aws_lambda_powertools.utilities.batch import BasePartialProcessor, batch_processor
import boto3
import os

table_name = os.getenv("TABLE_NAME", "table_not_found")

class MyPartialProcessor(BasePartialProcessor):
    """
    Process a record and stores successful results at a Amazon DynamoDB Table

    Parameters
    ----------
    table_name: str
        DynamoDB table name to write results to
    """

    def __init__(self, table_name: str):
        self.table_name = table_name

        super().__init__()

    def _prepare(self):
        # It's called once, *before* processing
        # Creates table resource and clean previous results
        self.ddb_table = boto3.resource("dynamodb").Table(self.table_name)
        self.success_messages.clear()

    def _clean(self):
        # It's called once, *after* closing processing all records (closing the context manager)
        # Here we're sending, at once, all successful messages to a ddb table
        with self.ddb_table.batch_writer() as batch:
            for result in self.success_messages:
                batch.put_item(Item=result)

    def _process_record(self, record):
        # It handles how your record is processed
        # Here we're keeping the status of each run
        # where self.handler is the record_handler function passed as an argument
        try:
            result = self.handler(record) # record_handler passed to decorator/context manager
            return self.success_handler(record, result)
        except Exception as exc:
            return self.failure_handler(record, exc)

    def success_handler(self, record):
        entry = ("success", result, record)
        message = {"age": result}
        self.success_messages.append(message)
        return entry


def record_handler(record):
    return randint(0, 100)

@batch_processor(record_handler=record_handler, processor=MyPartialProcessor(table_name))
def lambda_handler(event, context):
    return {"statusCode": 200}

Steps to Reproduce

1. Go to https://awslabs.github.io/aws-lambda-powertools-python/latest/utilities/batch/#create-your-own-partial-processor
2. Copy the example from Creating a custom batch processor

AWS Lambda Powertools for Python version

latest

AWS Lambda function runtime

3.9

Packaging format used

PyPi

Debugging logs

N/A

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