MiddleMan.Zero 1.1.2

MiddleMan.Zero

Core implementation of the MiddleMan.Zero mediator pattern library for .NET.

Overview

MiddleMan.Zero provides a lightweight, zero-ceremony implementation of the mediator pattern. It handles request/response workflows with built-in validation, error handling, and message logging.

Key Components

Base Classes

• HandlerBase<TRequest>: Abstract base class for handlers without a response
• HandlerBase<TRequest, TResponse>: Abstract base class for handlers with a typed response

Context

• HandlerContext: Manages handler execution state and message logging
  • Tracks request validation status
  • Logs debug, failure, invalid request, and not found messages
  • Provides access to all logged messages

Result Types

• Result: Concrete implementation of ResultBase
• Result<TResponse>: Concrete implementation of ResultBase<TResponse>

Message Types

• DebugMessage: For diagnostic information
• FailureMessage: For operation failures
• InvalidRequestMessage: For validation errors
• NotFoundMessage: For resource not found scenarios

Usage

Creating a Handler

public class GetOrderHandler : HandlerBase<GetOrderRequest, Order>
{
    protected override async Task ValidateAsync(
        GetOrderRequest request, 
        HandlerContext context, 
        CancellationToken cancellationToken)
    {
        if (request.OrderId <= 0)
        {
            context.AddInvalidRequestMessage("Invalid order ID");
        }
    }

    protected override async Task<Order?> HandleAsync(
        GetOrderRequest request, 
        HandlerContext context, 
        CancellationToken cancellationToken)
    {
        var order = await _repository.GetOrderAsync(request.OrderId);
        
        if (order == null)
        {
            context.NotFound("Order not found");
            return null;
        }
        
        return order;
    }
}

Handler Execution Flow

1. Request validation via ValidateAsync
2. Fast-fail if validation errors exist
3. Request processing via HandleAsync
4. Automatic result creation based on context state

Installation

dotnet add package MiddleMan.Zero

Dependencies

• MiddleMan.Zero.Abstractions

Related Packages

• MiddleMan.Zero.DependencyInjection: Automatic handler registration
• MiddleMan.Zero.AspNetCore.Mvc: ASP.NET Core MVC integration