试图激活 XXXXX 时无法解析 Microsoft.AspNetCore.SignalR.Hub`1[IXXXX] 类型服务
原标题：Unable to resolve service for type Microsoft.AspNetCore.SignalR.Hub`1[IXXXX] while attempting to activate XXXXX
I define my strong typed SignalR hub exactly by MS Rules
public class OutputMessages : Hub
{...}
than inject my SignalR hub to conctoller by the same way
public class ApplicationAPIController : ControllerBase
{
public ApplicationAPIController(IHubContext _outputMessages)
{...}
}
In Startup I add SignalR service as
services.AddSignalR()
.AddHubOptions(options =>
{
options.EnableDetailedErrors = true;
})
and define endpoint
app.UseEndpoints(endpoints =>
{
endpoints.MapHub("/OutputMessages", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
});
});
Looks good? Yes. And compilation is good. But in runTime I receive
fail: Microsoft.AspNetCore.SignalR.HubConnectionHandler[1]
Error when dispatching OnConnectedAsync on hub.
System.InvalidOperationException: Unable to resolve service for type Microsoft.AspNetCore.SignalR.Hub`1[IOutputMessages] while attempting to activate OutputMessages .
at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
at lambda_method(Closure , IServiceProvider , Object[] )
at Microsoft.AspNetCore.SignalR.Internal.DefaultHubActivator`1.Create()
at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.OnConnectedAsync(HubConnectionContext connection)
at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.OnConnectedAsync(HubConnectionContext connection)
at Microsoft.AspNetCore.SignalR.HubConnectionHandler`1.RunHubAsync(HubConnectionContext connection)
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[6]
OnConnectedAsync ending.
问题回答
and finally I found a solution
this is my strong type Hub definition
public class OutputMessages : Hub
{
public static readonly Dictionary ConnectedUserList = new Dictionary(1024);
private readonly IHubContext _hubContext;
private readonly ApplicationDbContext _db;
private readonly ILogger _logger;
public OutputMessages(IHubContext hubContext, ILogger logger, ApplicationDbContext dbContext)
{
_hubContext = hubContext;
_db = dbContext;
_logger = logger;
}
....
public async Task AdminMessages2(string userId, string message, bool consoleOnly)
{
string uname = await Username(userId);
await _hubContext.Clients.All.AdminMessages2(userId, "API: " + uname + " " + message, consoleOnly);
}
[ResponseCache(VaryByHeader = "id", Duration = 36000, Location = ResponseCacheLocation.Any)]
public async Task Username(string id)
{
ApplicationUser user = null;
await Task.Run(() => user = _db.Users.Find(id));
return user.UserName;
}
public override async Task OnConnectedAsync()
{
string JWT = Context.GetHttpContext().Request.Headers["Authorization"];
string ValidUserID = UserHelpers.ValidateJWT(JWT);
if (ValidUserID != null)
{
_logger.LogInformation($"User {ValidUserID} connected to {this.GetType().Name} hub");
if (ConnectedUserList.Any(x => x.Key == ValidUserID))
{
ConnectedUserList.Remove(ValidUserID);
}
ConnectedUserList.Add(ValidUserID, Context.ConnectionId);
}
await base.OnConnectedAsync();
}
public override async Task OnDisconnectedAsync(System.Exception exception)
{
var JWT = Context.GetHttpContext().Request.Headers["Authorization"];
string ValidUserID = UserHelpers.ValidateJWT(JWT);
if (ValidUserID != null)
{
_logger.LogInformation($"User {ValidUserID} disconnected from {this.GetType().Name} hub");
if (ConnectedUserList.Any(x => x.Key == ValidUserID))
{
ConnectedUserList.Remove(ValidUserID);
}
ConnectedUserList.Add(ValidUserID, Context.ConnectionId);
}
await base.OnDisconnectedAsync(exception);
}
}
and this is injection Hub to controller
public class ApplicationAPIController : ControllerBase
{
public ApplicationAPIController(ILogger logger, ApplicationDbContext dbContext, IConfiguration Configuration, CoreObjectDumper.CoreObjectDumper dump, IHubContext _outputMessages)
{
...
definition of SignalR service in StartUp not changed. Problem is create Hub from class instead interface and Hub constructor must be exactly IHubContext
In my case, I was using the ABP framework when this error occurred and I found that ABP (partially) removed the implementation of the class that lacked the DI, IOnlineClientManager
See: https://github.com/aspnetboilerplate/aspnetboilerplate/commit/30b70e9a7f4395a2103219cdfd4b9499d35ebf3b
The solution was then to remove the generic implementations of those classes ( and everywhere where they are being refferred)
IOnlineClientManager onlineClientManager,
here removing ChatChannel solved it for me.
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