Can't serialize poco class

I’m sening a POCO with a SignalR hub then, it gets sent to my subscribed client, but the data is lost.

The data I’m sending

public class WorkerOrderViewDto
    {
        public int Id { get; set; }
        public string UserName { get; set; } = string.Empty;
        public ICollection<SandwichDto> Sandwiches { get; set; } = new List<SandwichDto>();
        public OrderState State { get; set; }
    }
public enum OrderState
    {
        OrderPlaced,
        InTheOven,
        ToBeDelivered,
        Delivered,
    }

The Hub

public class WorkerViewOrderHub : Hub<IWorkerViewOrderClient>
    {
    }

    public interface IWorkerViewOrderClient
    {
        Task ReceiveOrderAddedAsync(WorkerOrderViewDto orders);
    }

Sending the data

private readonly IHubContext<WorkerViewOrderHub, IWorkerViewOrderClient> _workerViewHub;
public async Task<ActionResult> AddOrderAsync([FromBody] AddOrderDto addOrderDto)
        {
            var userId = _userManager.GetUserId(HttpContext.User) ?? throw new InvalidCommandException();
            addOrderDto.UserId = userId;
            addOrderDto.CustomerId = userId;

            var result = await _serverOrderService.AddOrderAsync(addOrderDto);

            var orderView = (await _serverOrderService.GetPendingOrdersForWorkerAsync()).SingleOrDefault(o => o.Id == result);

            await _workerViewHub.Clients.All.ReceiveOrderAddedAsync(orderView);

            return new OkResult();
        }

SignalR Client

_connection.On<WorkerOrderViewDto>(HubNames.WorkerViewOrderHubNames.ReceiveOrderAddedAsync, OnOrdersModifiedAsync);

            Task OnOrdersModifiedAsync(WorkerOrderViewDto order)
            {
                Orders.Add(order);

                OrdersChanged?.Invoke();

                return Task.CompletedTask;
            }

Chrom debug inspection of the serialized data: https://imgur.com/gallery/m37ptwF

The client connects, gets the message, OnOrdersMidifiedAsync gets called, but the data is not serialized properly. Any idea what I’m doing wrong?

[szmalec]

@KuraiAndras I didn’t really like the idea of adding the JsonPropertyName attribute to each model used in communication with SignalR 😉 so I tried to solve the problem on the server side where “camelCase” serialization occurs:

services
    .AddSignalR()
    .AddJsonProtocol(options => {
        // Configure the serializer to not change the casing of property names, instead of the default "camelCase" names.
        // Default camelCase is not supported by used Blazor.Extensions.SignalR, because it does NOT allow to specify JSON deserialization options - it just uses eg. JsonSerializer.Deserialize<TResult1>(payloads[0]) and there is no option to pass JsonSerializerOptions to System.Text.Json.JsonSerializer.Deserialize():
        // https://github.com/BlazorExtensions/SignalR/blob/v1.0.0/src/Blazor.Extensions.SignalR/HubConnection.cs#L108 + https://github.com/BlazorExtensions/SignalR/issues/64
        // Idea taken from: https://docs.microsoft.com/en-us/aspnet/core/signalr/configuration?view=aspnetcore-3.1&tabs=dotnet#jsonmessagepack-serialization-options
        options.PayloadSerializerOptions.PropertyNamingPolicy = null;
    });

Models in messages incomming to client side are then deserialized without problems (WARN: for outgoing models camelCase is still applied but this is not problem - model are properly deserialized on server side).

I have discovered that JsonPropertyName attribute is still required when using MessagePack otherwise we will encounter following exception on client side:

blazor.webassembly.js:1 Uncaught (in promise) Error: System.Text.Json.JsonException: The JSON value could not be converted to System.Decimal. Path: $.DecimalData | LineNumber: 0 | BytePositionInLine: 47. ---> System.InvalidOperationException: Cannot get the value of a token type 'String' as a number.
  at System.Text.Json.Utf8JsonReader.TryGetDecimal (System.Decimal& value) <0x24d8310 + 0x00018> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.Utf8JsonReader.GetDecimal () <0x24d8240 + 0x00008> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.Serialization.Converters.JsonConverterDecimal.Read (System.Text.Json.Utf8JsonReader& reader, System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options) <0x24d8188 + 0x00004> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.JsonPropertyInfoNotNullable`4[TClass,TDeclaredProperty,TRuntimeProperty,TConverter].OnRead (System.Text.Json.ReadStack& state, System.Text.Json.Utf8JsonReader& reader) <0x24d7f98 + 0x00030> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.JsonPropertyInfo.Read (System.Text.Json.JsonTokenType tokenType, System.Text.Json.ReadStack& state, System.Text.Json.Utf8JsonReader& reader) <0x2097e68 + 0x00078> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.JsonSerializer.HandleValue (System.Text.Json.JsonTokenType tokenType, System.Text.Json.JsonSerializerOptions options, System.Text.Json.Utf8JsonReader& reader, System.Text.Json.ReadStack& state) <0x2097a60 + 0x0009a> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
  at System.Text.Json.JsonSerializer.ReadCore (System.Text.Json.JsonSerializerOptions options, System.Text.Json.Utf8JsonReader& reader, System.Text.Json.ReadStack& readStack) <0x20947c8 + 0x00092> in <90ed82de44024ca1bc6b68be1a1a7e32>:0 
   --- End of inner exception stack trace ---
  at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
  at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) <0x1c47900 + 0x000c8> in <bceea5edb42b4ad28e0d8ad9d8e3fe0f>:0 
--- End of stack trace from previous location where exception was thrown ---

  at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.InvokeSynchronously (Microsoft.JSInterop.JSRuntime jsRuntime, Microsoft.JSInterop.Infrastructure.DotNetInvocationInfo& callInfo, Microsoft.JSInterop.Infrastructure.IDotNetObjectReference objectReference, System.String argsJson) <0x21badc0 + 0x00164> in <3eedf0ca90ca4e72bf6870618ca98c7c>:0 
  at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.BeginInvokeDotNet (Microsoft.JSInterop.JSRuntime jsRuntime, Microsoft.JSInterop.Infrastructure.DotNetInvocationInfo invocationInfo, System.String argsJson) <0x22023f8 + 0x00090> in <3eedf0ca90ca4e72bf6870618ca98c7c>:0 
    at Object.endInvokeDotNetFromJS (http://localhost:13425/_framework/blazor.webassembly.js:1:9849)
    at Object.invokeJSFromDotNet (http://localhost:13425/_framework/blazor.webassembly.js:1:9475)
    at _mono_wasm_invoke_js_marshalled (http://localhost:13425/_framework/wasm/mono.js:1:179080)
    at wasm-function[6361]:0x11d724
    at wasm-function[1463]:0x3f118
    at wasm-function[616]:0x1373b
    at wasm-function[616]:0x1eb39
    at wasm-function[616]:0x1eb17
    at wasm-function[616]:0x1eb17
    at wasm-function[616]:0x1eb17

[galvesribeiro]

If that is an API that is available on the original SignalR client and/or the JavaScript one yeah, we can have that.

The intent of this project is to wrap the JavaScript client and provide as much as possible the .Net API compatibility.