将复杂的Model对象传递给SignalR 2客户端时出现JSON序列化异常

Question

我得到了一个＆＃39; Newtonsoft.Json.JsonSerializationException＆＃39;将以下Model类的实例传递给SignalR 2客户端时：

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namespace MyApp.Models
{
    using System;
    using System.Collections.Generic;
    
    public partial class SensorCheckpoint
    {
        public int SensorCheckpointID { get; set; }
        public int SensorStatus { get; set; }
        public int LineMount { get; set; }
    
        public virtual Line Line { get; set; }
    }
}

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但是，如果我改为传递更简单的对象版本，则不会引发异常：

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namespace MyApp
{
    public class SensorCheckpointPush
    {
        public SensorCheckpointPush(SensorCheckpoint s) {
            this.SensorNumber = s.SensorCheckpointID;
            this.SensorStatus = s.SensorStatus;
            this.LineMount = s.LineMount;
        }
        public int SensorNumber { get; set; }
        public int SensorStatus { get; set; }
        public int LineMount { get; set; }
    }
}

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甚至可以将Model对象传递给客户端吗？如果是这样，它是如何完成的？ （我正在关注StockTicker示例，其中只传递简单对象）。将数据库对象发送到SignalR客户端的模式是什么？ 我花了好几个小时试图找到答案。

Stack Trace是：

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A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in mscorlib.dll
A first chance exception of type 'System.Net.WebSockets.WebSocketException' occurred in System.Web.dll
A first chance exception of type 'System.Net.WebSockets.WebSocketException' occurred in mscorlib.dll
A first chance exception of type 'System.OperationCanceledException' occurred in mscorlib.dll
A first chance exception of type 'System.OperationCanceledException' occurred in System.Web.dll
A first chance exception of type 'System.OperationCanceledException' occurred in mscorlib.dll
A first chance exception of type 'System.OperationCanceledException' occurred in mscorlib.dll
A first chance exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Microsoft.AspNet.SignalR.Core.dll
A first chance exception of type 'System.OperationCanceledException' occurred in mscorlib.dll

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