CQRS.Base 1.0.2

CQRS Pattern Library

This library provides a simple and extensible foundation for implementing the Command Query Responsibility Segregation (CQRS) pattern in .NET applications.

Features

• Command and Query Handler Interfaces: Define commands and queries with strong typing.
• Result Types: Standardized result objects for success, failure, and validation errors.
• Automatic DI Registration: Extension method to scan assemblies and register all command and query handlers as scoped services.

Getting Started

1. Define Commands, Queries, and Handlers

Command Example:

public class CreateUserCommand : ICommand<Guid>
{
    public string Name { get; set; }
}

Command Handler Example:

public class CreateUserCommandHandler : ICommandHandler<CreateUserCommand, Guid>
{
    public Task<Result<Guid>> Handle(CreateUserCommand command, CancellationToken cancellationToken)
    {
        // Business logic here
        return Task.FromResult(Result<Guid>.Success(Guid.NewGuid()));
    }
}

Query Example:

public class GetUserQuery : IQuery<UserDto>
{
    public Guid UserId { get; set; }
}

Query Handler Example:

public class GetUserQueryHandler : IQueryHandler<GetUserQuery, UserDto>
{
    public Task<Result<UserDto>> Handle(GetUserQuery query, CancellationToken cancellationToken)
    {
        // Business logic here
        return Task.FromResult(Result<UserDto>.Success(new UserDto()));
    }
}

2. Register Handlers in DI

In your Program.cs or Startup.cs:

using CQRS.Base;
using System.Reflection;

var builder = WebApplication.CreateBuilder(args);

// Register all CQRS handlers from the current assembly
builder.Services.AddCQRSHandlersFromAssembly(Assembly.GetExecutingAssembly());

var app = builder.Build();
// ...

3. Use Handlers via Minimal API

app.MapPost("/users", async (CreateUserCommand command, ICommandHandler<CreateUserCommand, Guid> handler, CancellationToken cancellationToken) =>
{
    var result = await handler.Handle(command, cancellationToken);
    return result.IsSuccess
        ? Results.Ok(result.Value)
        : Results.BadRequest(result.ErrorMessage);
});

Summary

• Define your commands, queries, and handlers.
• Register all handlers with one line using the provided extension method.
• Use handlers via DI in your application.

This approach keeps your codebase clean, testable, and scalable using the CQRS pattern.