I started using unity to inject stuff into one of my hubs. This works, but, when I resolve a hubcontext somewhere outside my hub it seems like i'm getting the wrong one. This is because when I try to send messages with it, connected clients don't get them.
Dependencyresolver:
public class SignalRUnityDependencyResolver : DefaultDependencyResolver, IDependencyResolver
{
private IUnityContainer _container;
public SignalRUnityDependencyResolver(IUnityContainer container)
{
_container = container;
}
public override object GetService(Type serviceType)
{
if (_container.IsRegistered(serviceType)) return _container.Resolve(serviceType);
else return base.GetService(serviceType);
}
public override IEnumerable<object> GetServices(Type serviceType)
{
if (_container.IsRegistered(serviceType)) return _container.ResolveAll(serviceType);
else return base.GetServices(serviceType);
}
}
What I register in my container:
container.RegisterType<MessageHub>(new InjectionConstructor(new EFAuthRepository()));
My hub:
public class MessageHub : Hub
{
IAuthRepository _repository;
public MessageHub(IAuthRepository repository)
{
_repository = repository;
}
How I resolve outside my hub:
var context = GlobalHost.ConnectionManager.GetHubContext<MessageHub>();
Is there anything else that needs to be registred?
You should use the instance of the resolver to get the IConnectionMananger from the container as explained here.
Althought it is for Ninject you can get the idea. (look at at the bottom). This ConnectionManager can get you the HubContext as you were used to via GlobalHost.
resolver.Resolve<IConnectionManager>().GetHubContext<MessageHub>()
We made a simple example to ilustrate this (Ninject and Unity examples using signalr) and you can check it out here. If you are eager for the setup, it is here. ;)
Let me know if it helps.
Related
I'm learning .Net Core SignalR and investigating how I could use it with my app live charts. I play with some examples on the net and they all work, but I don't know how to use SignalR with database polling. I'm getting below error:
Cannot access a disposed object ...
I'm assuming it is related to my contex is being disposed after request is completed. I'm using dependency injection.
ChatController
public class ChatController : ControllerBase
{
private IChatService _chatService;
private IChatContext<ChatHub> _hub;
public ChatController(IChatContext<ChatHub> hub, IChatService chatService)
{
_hub = hub;
_chatService = chatService;
}
public IActionResult Get()
{
var timerManager = new TimerManager(() => _hub.Clients.All.SendAsync("transferchatdata", _chatService.ChatDataByProds()));
return Ok(new { Message = "Request Completed" });
}
}
ChatService
public interface IChatService
{
IEnumerable<ChatDataByProd> ChatDataByProds();
}
public class ChatService : IChatService
{
private ChatContext _context;
public ChatService(ChatContext context)
{
_context = context;
}
public IEnumerable<ChatDataByProd> ChatDataByProds()
{
return _context.ChatDataByProds;
}
}
ChatHub
public class ChatHub : Hub
{
}
It seems that you are using a EF Core context that is a scoped lifetime service, which means per-request lifetime in ASP.NET Core. Your ChatService must have a longer lifetime than a HTTP request, and a single instance of the database context would be disposed by the container while you are still holding the reference to it.
Thus, you need to obtain an IServiceProvider container in the ctor of ChatService, and GetService the database context each time when you need to access the database.
Is there a good way to call methods in SignalR hub from a controller ?
Right now I have this:
public class StatsHub : Hub
{
private static readonly Lazy<StatsHub> instance = new Lazy<StatsHub>(() => new StatsHub());
public static StatsHub Instance { get { return instance.Value; } }
public StatsHub()
{
if (this.Clients == null)
{
var hubContext = SignalR.GlobalHost.ConnectionManager.GetHubContext<StatsHub>();
this.Clients = hubContext.Clients;
this.Groups = hubContext.Groups;
}
}
// methods here...
}
so in my controller actions I can just say, for example
StatsHub.Instance.SendMessage("blah");
and it's almost good, except that hubContext doesn't have Caller or Context properties of Hub - which are nice to have.
Hopefully, there's a better way to do this ?
If you want to broadcast over a hub from outside of the hub, you need GlobalHost.ConnectionManager.GetHubContext<MyHub>() to get ahold of the hub context. You can then use this context to broadcast via the .Clients property.
As indicated in your sample code you already get ahold of the hub context, but doing so inside the hub just doesn't feel right in my opinion. If you're only using the logic in SendMessage() from your controller actions, I'd move the code right into the controller action and use the hub context obtained via GetHubContext<T>() from there.
Please note that the Caller or Context property will always be null in this scenario, because SignalR wasn't involved when making a request to the server and therefore cannot provide the properties.
Found a DefaultHubManager, which is what I need, I think.
DefaultHubManager hd = new DefaultHubManager(GlobalHost.DependencyResolver);
var hub = hd.ResolveHub("AdminHub") as AdminHub;
hub.SendMessage("woohoo");
Works. If there's an even better/preferred way - please share.
As per the latest documentation, IHubContext can be injected by dependency injection.
documentation : https://learn.microsoft.com/en-us/aspnet/core/signalr/hubcontext?view=aspnetcore-6.0
In service you could do
public class NotificationService : INotificationService
{
private readonly IHubContext<NotificationHub> _hubContext;
public NotificationService(IHubContext<NotificationHub> hubContext)
{
_hubContext = hubContext;
}
}
In controller
public class HomeController : Controller
{
private readonly IHubContext<NotificationHub> _hubContext;
public HomeController(IHubContext<NotificationHub> hubContext)
{
_hubContext = hubContext;
}
}
Once you have HubContext you could send message to group/client etc.
public async Task SendMessage()
{
return await _hubContext.Clients.All.SendAsync("Notify", $"Hello world");
}
I'm using SignalR 0.5.2 and I'm trying to get a DependencyResolver set up using Unity. I've written the simplest code I can. I have a hub that I'm trying to inject into which looks like this:
public class SimpleHub : Hub
{
private readonly ITestService _service;
public SimpleHub(ITestService service)
{
_service = service;
}
public void Update()
{
Clients.callback("Kevin");
}
}
and a DependencyResolver that looks like this:
public class UnityDependencyResolver : DefaultDependencyResolver
{
private readonly IUnityContainer _container;
public UnityDependencyResolver(IUnityContainer container)
{
_container = container;
}
public override object GetService(Type serviceType)
{
if (_container.IsRegistered(serviceType))
{
return _container.Resolve(serviceType);
}
return base.GetService(serviceType);
}
public override IEnumerable<object> GetServices(Type serviceType)
{
if (_container.IsRegistered(serviceType))
{
return _container.ResolveAll(serviceType);
}
return base.GetServices(serviceType);
}
}
I register the dependency resolver in Global.asax
protected void Application_Start()
{
IUnityContainer container = new UnityContainer();
InitializeContainer(container);
SignalR.IDependencyResolver resolver = new UnityDependencyResolver(container);
GlobalHost.DependencyResolver = resolver;
RouteTable.Routes.MapHubs();
// more MVC stuff here
}
where InitializeContainer register the ITestService in Unity
The resolver "works" in that it's getting called for all the SignalR types, and if I leave my hub with a default constructor it all gets loaded. However the resolver never gets asked to resolve the ITestService interface.
I've also tried passing the resolver to MapHubs, still no luck. I've also tried property injection using the [Dependency] attribute and that didn't work either.
Do I need to register the resolver with MVC as well? (I have tried that by implementing both IDependecyResolver interfaces but get an exception telling me the resolver doesn't implement IServiceLocator)
So I've sort of fixed this. I wondered if the fact that the Hub was registered with the signalr container and the interface was registered with the Unity container was causing the issue. So I registered the Hub with Unity and then everything works.
This sort of makes sense as there are two containers.
Is this the standard behaviour?
In case someone else is wondering... I found a good SPA example that uses
SignalR 1.0.1
Unity 3
A bunch of other frameworks
The interesting thing is the way he create the container, the dependencies and everything else. Worth checking it out.
I am using unity, entity framework 4 with POCO classes, repository pattern for DAL and services for Business Logic control.
I also want to use Unit of Work so I can package together CRUD operations which I perform on different services and then commit them all together.
My question is what would be the proper way to inject the Unit Of Work mechanism into my application using Microsoft Unity?
I understand that I can put the IUnitOfWork together with the repository on the constructor of the proper service and then if Unity mapping is specified it would auto initiate the proper instances, but this way I do not pass the global unit of work but rather create a new instance on each level, which can't be a smart way to do it (actually the repository is initiated even before the service).
What am I missing? (Attached is constructor code as I wrote it now of service and its repository).
U also understand that I can use Unity's ParameterOverrides method to take some global instance of Unit of Work (lets say from my aspx.cs file) and pass it into the service and then into the repository. But it seems a bit lame. Is this my only option?
Thanks
public class GenericRepository<T> : IUnitOfWorkRepository, IGenericRepository<T> where T : BaseEntity, IAggregateRoot
{
private IUnitOfWork _uow;
/// <summary>
/// Returns the active object context
/// </summary>
private ObjectContext ObjectContext
{
get
{
return ObjectContextManager.GetObjectContext();
}
}
public GenericRepository(IUnitOfWork uow)
{
_uow = uow;
}
//blahhhh...
public void Add(T entity)
{
_uow.RegisterNew(entity, this);
}
public void Delete(T entity)
{
_uow.RegisterRemoved(entity, this);
}
//.....blah blah....
public void PersistCreationOf(IAggregateRoot entity)
{
this.ObjectContext.AddObject(GetEntitySetName(), entity);
}
public void PersistUpdateOf(IAggregateRoot entity)
{
// Do nothing as EF tracks changes
}
public void PersistDeletionOf(IAggregateRoot entity)
{
this.ObjectContext.DeleteObject(entity);
}
}
public class CategoryRepository : GenericRepository<XComSolutions.FB.Domain.Model.Entities.Category>, ICategoryRepository
{
public CategoryRepository(IUnitOfWork uow)
: base(uow)
{ }
}
public class CategoryService : ICategoryService
{
public int myID {get; set;}
private ICategoryRepository _categoryRepository;
private IUnitOfWork _uow;
public CategoryService(ICategoryRepository categoryRepository,
IUnitOfWork uow)
{
_categoryRepository = categoryRepository;
_uow = uow;
}
public List<Category> GetAll()
{
return _categoryRepository.GetAll();
}
}
Define an IUnitOfWorkFactory and inject that in your services:
public class Service
{
private readonly IUnitOfWorkFactory factory;
public Service(IUnitOfWorkFactory factory)
{
this.factory = factory;
}
public void DoOperation()
{
using (UnitOfWork context = this.factory.CreateNew())
{
this.DoSomeStuff(context);
this.DoMoreStuff(context);
context.SubmitChanges();
}
}
}
What I think you need to do is to define unit of work factory. You register this factory with your DI container and you resolve for this factory every time you need your unit of work. Then you get unit of work from the factory, work with it and let it go. You often will see that you need your unit of work within a scope of single method or single class. This article discuss Unit of Work pattern in connection with Entity Framework: http://msdn.microsoft.com/en-us/magazine/dd882510.aspx
I am new to WCF i am using constructor in my WCF service.svc.cs file....It throws this error when i use the constructor
The service type provided could not be loaded as a service because it does not have a default (parameter-less) constructor.
To fix the problem, add a default constructor to the type, or pass an instance of the type to the host.
When i remove the constructor its working fine....But its compulsory that i have to use constructor...
This is my code
namespace UserAuthentication
{
[ServiceBehavior(InstanceContextMode=System.ServiceModel.InstanceContextMode.Single)]
public class UserAuthentication : UserRepository,IUserAuthentication
{
private ISqlMapper _mapper;
private IRoleRepository _roleRepository;
public UserAuthentication(ISqlMapper mapper): base(mapper)
{
_mapper = mapper;
_roleRepository = new RoleRepository(_mapper);
}
public string EduvisionLogin(EduvisionUser aUser, int SchoolID)
{
UserRepository sampleCode= new UserRepository(_mapper);
sampleCode.Login(aUser);
return "Login Success";
}
}
}
can anyone provide ideas or suggestions or sample code hw to resolve this issue...
You could add something like (if possible):
public UserAuth() : this(SqlMapperFactory.Create())
{
}