MSHelper.CQRS.Events 1.0.0

MSHelper.CQRS.Events : Events

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Overview

Adds an ability to create and process Events in the sense of CQRS.

Installation

This document is for the latest MSHelper.CQRS.Events 1.0.0 release and later.

dotnet add package MSHelper.CQRS.Events

Dependencies

-- MSHelper

Usage

Implement IEvent or IRejectedEvent (marker) interface in the selected class. Since the event represents something that already happened, you should follow the convention:

--- keep all the events immutable --- name of your events should kept in the past tense

public class AccountCreated : IEvent
{
    public Guid Id { get; }

    public AccountCreated(id)
    {
        Id = id;
    }
}

Create dedicated event handler class that implements IEventHandler<TEvent> interface with HandleAsync() method:

public class AccountCreatedHandler : IEventHandler<AccountCreated>
{
    public Task HandleAsync(AccountCreated @event)
    {
        //put the handling code here
    }
}

You can easily register all command handlers in DI container by calling AddEventHandlers() method on IMSHelperBuilder:

public IServiceProvider ConfigureServices(this IServiceCollection services)
{
    var builder = services.AddMSHelper()
        .AddEventHandlers();

    //other registrations    
    return builder.Build();
}

Dispatching a particular command object can be also done using MSHelper package. Start with registering in-memory dispatcher on your IMSHelperBuilder by calling a AddInMemoryEventDispatcher() method:

public IServiceProvider ConfigureServices(this IServiceCollection services)
{
    var builder = services.AddMSHelper()
        .AddCommandHandlers()
        .AddInMemoryEventDispatcher();

    //other registrations    
    return builder.Build();
}

Then simply inject IEventDispatcher into a class and call DispatchAsync() method:

public class AccountsService
{
    private readonly IEventDispatcher _dispatcher;

    public AccountsService(IEventDispatcher dispatcher)
    {
        _dispatcher = dispatcher;
    } 

    public Task PostProcessAccountCreation(AccountCreated @event)
        => _dispatcher.DispatchAsync(@event);
}

Important Note:

All the MSHelper packages are for self learning purposes inspired by Devmentors.io