How to send an object with a collection of generic through SignalR on Asp.Net Core

J4N 0
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On my Asp.Net core web app, I'm using SignalR to provide to my angular app some live update. One of the callback is sending data to the client

public class DataBatch
{
    public Guid DashboardId { get;set; }
    public IEnumerable<WidgetData> WidgetData { get;set; }
    public DateTime RefreshDate { get;set; }
}
public abstract class WidgetData
{
    public Guid WidgetUsageId { get; set;}
    public DateTime Timestamp { get; set;}
}

The issue is that WidgetData is abstract, and most of its implementations have additionals values. Typically:

public class ValueIndicatorData : WidgetData
{
    public IList<ValueIndicatorValue> ValueIndicatorValues { get; } = new List<ValueIndicatorValue>();
}

When I send my data to my clients:

await _hubContext.Clients.Group(dashboardId).SendDashboardData(notification.DataBatch);

My clients only receives the properties declared in WidgetData, not the one of my children classes(like the ValueIndicatorData).

How can I provide to SignalR the informations that this object has sub-classes and that their properties should be serialized?

signalr-hub signalr websocket asp.net-core .net
1 Answers

I ended configuring Asp.Net Core to use NewtonSoft to serialize to JSON, while setting an option to include types, now it automatically serialize the data:

    builder.Services.AddSignalR()
        .AddNewtonsoftJsonProtocol(opts =>
        {
            opts.PayloadSerializerSettings.TypeNameHandling = TypeNameHandling.Auto;
        });

There is an alternative using the native JSON converter, but it require to build some cumbersome converters:

https://docs.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-converters-how-to?pivots=dotnet-6-0#support-polymorphic-deserialization

J4N0
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