C#•9mo ago

❔ Mediatr Notification using a Base Class Not Publishing

I'm using a base class as a constraint on a generic notification in mediatr. When I publish my notification via mediatr my notification handler isn't found. I believe mediatr is supposed to support this idea; so maybe I'm just chasing a red-herring.

<Project Sdk="Microsoft.NET.Sdk.Worker">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="MediatR" Version="12.1.1" />
    <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.1" />
  </ItemGroup>
</Project>

<Project Sdk="Microsoft.NET.Sdk.Worker">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="MediatR" Version="12.1.1" />
    <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.1" />
  </ItemGroup>
</Project>

using MediatR;

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.AddMediatR(o=>o.RegisterServicesFromAssembly(typeof(Program).Assembly));
    })
    .Build();


host.Start();

var mediator = host.Services.GetRequiredService<IMediator>();

Console.WriteLine("Sending Event One");
await mediator.Publish(new EventNotification<EventOne>());

Console.WriteLine("Sending Event Two");
await mediator.Publish(new EventNotification<EventTwo>());

class EventHandler<TModel> : NotificationHandler<EventNotification<TModel>> where TModel : TestEvent
{
    protected override void Handle(EventNotification<TModel> notification)
    {
        Console.WriteLine(notification.Model.DateTime);
    }
}

class EventNotification<T> : INotification where T : TestEvent
{
    public T Model { get; set; }
}

abstract class TestEvent
{
    public DateTime DateTime = DateTime.Now;
}

class EventOne : TestEvent
{

}

class  EventTwo:TestEvent
{
    
}

using MediatR;

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.AddMediatR(o=>o.RegisterServicesFromAssembly(typeof(Program).Assembly));
    })
    .Build();


host.Start();

var mediator = host.Services.GetRequiredService<IMediator>();

Console.WriteLine("Sending Event One");
await mediator.Publish(new EventNotification<EventOne>());

Console.WriteLine("Sending Event Two");
await mediator.Publish(new EventNotification<EventTwo>());

class EventHandler<TModel> : NotificationHandler<EventNotification<TModel>> where TModel : TestEvent
{
    protected override void Handle(EventNotification<TModel> notification)
    {
        Console.WriteLine(notification.Model.DateTime);
    }
}

class EventNotification<T> : INotification where T : TestEvent
{
    public T Model { get; set; }
}

abstract class TestEvent
{
    public DateTime DateTime = DateTime.Now;
}

class EventOne : TestEvent
{

}

class  EventTwo:TestEvent
{
    
}

2 Replies

Mayor McCheese•9mo ago

I've talked to a few folks and they think this should work too. I might open a mediatr issue.

Accord•9mo ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

Gaming

Programming

❔ Mediatr Notification using a Base Class Not Publishing