Command Query Seperation Framework
$ dotnet add package CommandQuery.FramingBreaking changes for version 1.0.4 and higher
public void ConfigureServices(IServiceCollection services)
{
/// this will add required interface
/// this will also search your assemblies for
/// types that can be handled
services
.AddCommandQuery(<Your assemblies here>);
}
Inject the IBroker into your class Call
public class TestController:Controller
{
private ICommandBroker _broker;
public TestController(IBroker broker)
{
_broker = broker;
}
[Route("/widget")]
[HttpPost]
public asycn Task<IActionResult> CreateWidget(Widget request)
{
// execute command
var result = await _broker.HandleAsync<Widget, CommandResponse<string>>(request);
//check command result
if(result.Success)
{
// return success
return Ok(result.Data);
}
// throw on failure
throw new BadRequestException(result.Message, result.Exception);
}
}
public class CreateWidget : IAsyncHandler<CreateWidgetMessage, CommandResponse<string>>
{
private readonly IDomainEventPublisher _publisher;
public CreateWidget(IDomainEventPublisher publisher)
{
_publisher = publisher;
}
public async Task<CommandResponse<string>> Execute(CreateWidgetMessage message)
{
var response = Guid.NewGuid().ToString();
_publisher.MessageResult += (sender, eventargs) =>
{
response += $" message was sent and processed with Success={eventargs.Success}";
};
await _publisher.Publish(new WidgetCreated());
return Response.Ok(response);
}
}
ICommandHandler CommandHandler IAsyncCommandHandler AsyncCommandHandler ICommandBroker CommandBroker IQueryHandler QueryHandler IAsyncQueryHandler AsyncQueryHandler IDomainEventPublisher DomainEventPublisher ICommandBroker CommandBroker CommandResponse IDomainEvent
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<ICommandBroker, CommandBroker>();
service.AddTransient<IDomainEventPublisher, DomainEventPublisher>();
service.AddTransient<ICommandHandler<CreateMessage,CommandResponse>, CreateNewWidgetCommand>();
service.AddTransient<IQueryHandler<GetWidget,Widget>, GetWidgetQuery>();
}Inject the ICommandBroker into your class Call
public class TestController:Controller
{
private ICommandBroker _commandBroker;
public TestController(ICommandBroker commandBroker)
{
_commandBroker = commandBroker;
}
[Route("/widget")]
[HttpPost]
public asycn Task<IActionResult> CreateWidget(Widget request)
{
// execute command
var result = await _commandBroker.ExecuteAsync<Widget, CommandResponse>(request);
//check command result
if(result.Result == CommandStatus.Success)
{
// return success
return Ok();
}
// throw on failure
throw new BadRequestException(result.Message, result.Exception);
}
}Command Handler is used for inserting, updating, or deleting data from your database. The DomainEventPublisher is used to publish an outbound message for your domain or the message could be sent to a message queue. Ideally commands should be encapsulated and should not call other commands or queries. If you need to query for data then it should be part of the command encapsulating the functionality.
public class WidgetCommand : AsyncCommandHandler<CreateNewWidgetMessage,CommandResponse>
{
public WidgetCommand(IDomainEventPublisher) : base(domainEventPublisher)
public override async Task<CommandResponse> Execute(CreateNewWidgetMessage createNewWidgetMessage)
{
//do your work here
//publish your message accross the domain
DomainEventPublisher.Publish(new MessageHere());
return CommandResponse.Okay();
}
}Query Handler is used for fetching data from your data source and returning a projection.
public class GetWidgetDataQuery:IAsyncQueryHandler<GetWidgetDataRequest, WidgetModel>
{
public async Task<WidgetModel> Execute(GetWidgetDataRequest message)
{
//query for your data here
//do some work
return result;
}
}