Attribute registration extension for Xer.Cqrs.CommandStack

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Installation

You can simply clone this repository, build the source, reference the dll from the project, and code away!

Xer.Cqrs.CommandStack.Extensions.Attributes library is available as a Nuget package:

To install Nuget packages:

1. Open command prompt
2. Go to project directory
3. Add the packages to the project:

   dotnet add package Xer.Cqrs.CommandStack.Extensions.Attributes
   

4. Restore the packages:

   dotnet restore
   

Command Handler Attribute Registration

// Example command.
public class RegisterProductCommand
{
    public int ProductId { get; }
    public string ProductName { get; }

    public RegisterProductCommand(int productId, string productName) 
    {
        ProductId = productId;
        ProductName = productName;
    }
}

// Example Command handler.
public class RegisterProductCommandHandler : ICommandAsyncHandler<RegisterProductCommand>
{
    private readonly IProductRepository _productRepository;

    public RegisterProductCommandHandler(IProductRepository productRepository)
    {
        _productRepository = productRepository;
    }

    [CommandHandler] // This is in Xer.Cqrs.CommandStack.Extensions.Attributes. This allows the method to registered as a command handler through attribute registration.
    public Task HandleAsync(RegisterProductCommand command, CancellationToken cancellationToken = default(CancellationToken))
    {
        return _productRepository.SaveAsync(new Product(command.ProductId, command.ProductName));
    }
}

// Command Handler Registration
public CommandDelegator RegisterCommandHandlers()
{            
    // SingleMessageHandlerRegistration only allows registration of a single message handler per message type.
    var registration = new SingleMessageHandlerRegistration();
    
    // Register methods with [CommandHandler] attribute.
    registration.RegisterCommandHandlerAttributes(() => new RegisterProductCommandHandler(new ProductRepository()));

    // Build command delegator.
    IMessageHandlerResolver resolver = registration.BuildMessageHandlerResolver();
    return new CommandDelegator(resolver);
}