Python CQRS Dispatcher

CQRS dispatcher that integrates python-cqrs-core with gridflow-python-mediator for type-safe command/query dispatch.

Installation

pip install python-cqrs-dispatcher

Features

• Type-Safe Dispatch: Separate command/query dispatch methods
• Handler Registry: Track registered handlers
• Pipeline Behaviors: Built-in support via mediator
• Bulk Registration: Register multiple handlers at once
• Auto-Discovery: Auto-register handlers from modules

Usage

Basic Setup

from python_cqrs_dispatcher import CQRSDispatcher
from python_cqrs_core import BaseCommand, ICommandHandler

class CreateUserCommand(BaseCommand):
    name: str
    email: str

class CreateUserHandler(ICommandHandler[CreateUserCommand, int]):
    async def handle(self, command: CreateUserCommand) -> int:
        # Create user logic
        return user_id

# Setup dispatcher
dispatcher = CQRSDispatcher()
dispatcher.register_command_handler(
    CreateUserCommand,
    CreateUserHandler()
)

# Dispatch command
cmd = CreateUserCommand(name="John", email="john@example.com")
user_id = await dispatcher.send_command(cmd)

With Queries

from python_cqrs_core import BaseQuery, IQueryHandler

class GetUserQuery(BaseQuery):
    user_id: int

class GetUserHandler(IQueryHandler[GetUserQuery, User]):
    async def handle(self, query: GetUserQuery) -> User:
        return await db.get_user(query.user_id)

dispatcher.register_query_handler(GetUserQuery, GetUserHandler())

query = GetUserQuery(user_id=1)
user = await dispatcher.send_query(query)

Bulk Registration

from python_cqrs_dispatcher import register_handlers

handlers = [
    (CreateUserCommand, CreateUserHandler()),
    (UpdateUserCommand, UpdateUserHandler()),
    (GetUserQuery, GetUserHandler()),
    (ListUsersQuery, ListUsersHandler()),
]

register_handlers(dispatcher, handlers)

Pipeline Behaviors

from gridflow_python_mediator import LoggingBehavior, TimingBehavior

# Add behaviors (execute before all handlers)
dispatcher.add_pipeline_behavior(LoggingBehavior().handle)
dispatcher.add_pipeline_behavior(TimingBehavior().handle)

Auto-Registration

from python_cqrs_dispatcher import auto_register_handlers
import my_app.handlers

# Auto-discover and register all handlers
auto_register_handlers(dispatcher, my_app.handlers)

API Reference

CQRSDispatcher

Type-safe CQRS dispatcher.

Methods:

register_command_handler(command_type, handler)

Register command handler.

Parameters:

• command_type (Type[ICommand]): Command class
• handler (ICommandHandler): Handler instance

register_query_handler(query_type, handler)

Register query handler.

Parameters:

• query_type (Type[IQuery]): Query class
• handler (IQueryHandler): Handler instance

async send_command(command) -> Any

Dispatch command.

Parameters:

• command (ICommand): Command to dispatch

Returns:

• Command result

async send_query(query) -> Any

Dispatch query.

Parameters:

• query (IQuery): Query to dispatch

Returns:

• Query result

add_pipeline_behavior(behavior)

Add pipeline behavior.

Parameters:

• behavior (Callable): Behavior function

Helper Functions

register_handlers(dispatcher, handlers)

Bulk register handlers.

Parameters:

• dispatcher (CQRSDispatcher): Dispatcher instance
• handlers (List[Tuple[Type, Any]]): Handler tuples

auto_register_handlers(dispatcher, module)

Auto-discover and register handlers.

Parameters:

• dispatcher (CQRSDispatcher): Dispatcher instance
• module (Module): Python module to scan

Dependencies

• python-cqrs-core>=0.1.0
• gridflow-python-mediator>=0.1.0

License

MIT