Sending custom class via SignalR to Blazor WebAssembly - signalr

Question

I have issue with sending custom class via SignalR hub to client (Blazor WebAssembly).
I have worker process, that is periodically sending data to all connected clients. If I try to send standard data, string, List of strings, Date etc. Client can process it without any problems.
But when I try to send my own "data class" I am receiving this error
Microsoft.AspNetCore.SignalR.Client.HubConnection[57]
Failed to bind arguments received in invocation '(null)' of 'ReceiveProject'.
System.IO.InvalidDataException: Error binding arguments. Make sure that the types of the provided values match the types of the hub method being invoked. ---> System.NotSupportedException: Deserialization of reference types without parameterless constructor is not supported. Type 'SekvenceReport.Shared.Project'
Here is my custom class
Custom class
public class Project
{
public Project(string name, string[] dbtable)
{
this.Name = name;
this.DbTable = dbtable;
this.Slbs = new List<Slb>();
this.Duplicity = true;
this.EdiError = true;
}
public string Name { get; set; }
public string[] DbTable { get; set; }
public List<Slb> Slbs { get; set; }
public bool Duplicity { get; set; }
public bool EdiError { get; set; }
}
public class Slb
{
public Slb(string slbid)
{
this.SlbId = slbid;
this.Sekvences = new List<Sequence>();
this.Status = "Připraveno";
}
public Slb()
{
}
public string SlbId { get; set; }
public List<Sequence> Sekvences { get; set; }
public string Status { get; set; }
public string StatusAsn { get; set; }
public string StatusEvaluation()
{
string eval = this.Status;
if (this.Sekvences.Any(i => i.Status == "D") && this.Sekvences.Any(i => i.Status == "N"))
{
eval = "Sekvencování";
this.Status = eval;
return this.Status;
}
else if (this.Sekvences.Any(i => i.Status == "D"))
{
eval = "Uvolněno";
this.Status = eval;
return this.Status;
}
else if (this.Sekvences.Any(i => i.Status == "N"))
{
if (this.Sekvences.Any(i => i.LoadingStatus == true) && this.Sekvences.Any(i => i.LoadingStatus == false))
{
eval = "Nakládání";
this.Status = eval;
return this.Status;
}
else if (this.Sekvences.Any(i => i.LoadingStatus == false))
{
eval = "Nasekvencováno";
this.Status = eval;
return this.Status;
}
else if (this.Sekvences.Any(i => i.LoadingStatus == true))
{
eval = "Naloženo";
this.Status = eval;
return this.Status;
}
}
eval = "Neznámý stav";
this.Status = eval;
return eval;
}
}
How server is sending data from Worker
await _projectHubContext.Clients.All.SendAsync("ReceiveProject", Data.projects);
How client is reading data
hubConnection = new HubConnectionBuilder()
.WithUrl(NavigationManager.ToAbsoluteUri("/projecthub"))
.ConfigureLogging(logging => logging.AddProvider(LoggerProvider))
.Build();
//Processing custom class (List of Projects)
hubConnection.On<List<Project>>("ReceiveProject", (listProjects) =>
{
var vars = listProjects;
//projects.AddRange(listProjects);
projects.AddRange(vars);
StateHasChanged();
});

Answer 1

Try adding a constructor to your Project class without parameters, for example:
public class Project
{
public Project()
{
}
// Rest of class
}