dynamodb-stream-router

WARNING - Version 0.0.6 is a breaking change from version 0.0.5. Please review the documentation before upgrading

Provies a framework for mapping records in a Dynamodb stream to callables based on the event name (MODIFY, INSERT, DELETE) and content.

Installation

pip install dynamodb-stream-router

Routing

• Routes are determined by examining the eventName in the dynamodb section of the DynamoDB stream Record and through a condition which examines the contents of the Record.
• Conditions can either be a callable that takes a RouteRecord and returns True or False, or it may be a string expression that will be parsed into a callable. See below for the expression language.
• Routes have a priority, which is honored in an acending order. If multiple matching routes have the same priority, they will be executed in random order (concurrectly, if an executor is provided)
• Routes are matched based on a RouteRecord, which is a helper class that (lazily) deserializers the DynamoDB item structure (used in Keys, NewImage and OldImage) into Python types, exactly in the same way that the boto3 dynamodb Table resource does.
• Route handling functions take a RouteRecord and can return anything. The return value is not used by the framework.

Expressions

Keywords and types:

Operators:

Comparison operators, except for regex comparison, can compare PATH to VALUE, PATH to PATH, or even VALUE to VALUE.

functions

Examples

from dynamodb_stream_router import on_insert, on_modify, on_remove, on_operations, Operation, route_records, RouteRecord

@on_insert("$NEW.foo == 'bar'", 0)
def print_new_record(record: RouteRecord) -> None:
    print(record.new_image)

def test_old_foo(record: RouteRecord) -> bool:
    return record.old_image["foo"] == "bar2"

@on_remove(test_old_foo, 0)
def print_old_record(record: RouteRecord) -> None:
    print(record.old_record)

@on_modify("has_changed('foo') & attribute_exists($NEW.foo)", 1)
def print_changed_foo(record: RouteRecord) -> None:
    print(f'{record.old_image.get("foo")} -> {record.new_image.get("foo")}')

@on_operations({Operation.INSERT, Operation.MODIFY, Operation.REMOVE}, 1)
def hello_world(record: RouteRecord) -> str:
    return "Hello, DB STREAM"

def lambda_handler(event, context):
    route_records(event["Records"])