WCF 调用协定中的“获取”数据成员返回 null

我的服务协定中有一个操作协定，叫做

Schedule[] GetScheduleObjects();

我在那个操作合约中有一个名为"任务"的数据管理器，它返回一个子对象列表。

[DataMember()]
public Task[] Tasks

问题是当调用操作协定时，该方法会执行，但"任务"的"get"会发生两次。第一次它包含有效的运行时实例，第二次为 null，这会导致序列化异常。尽管只调用了一次服务，但也会发生这种情况。绑定是使用双工代理的 tcp 连接。想法？？？？？

数据合约

[DataContract()]
public class Schedule
{
    public Schedule(string name)
    {
        this.Name = name;
    }
    [DataMember()]
    public string Name { get; private set; }
    [DataMember()]
    public bool Running { get; set; }
    /// <summary>
    /// Schedule Task is a DataMember object, do not modify
    /// </summary>
    [DataMember()]
    public Task[] Tasks
    {
        get { return _Tasks.ToArray(); }
    }
    private List<Task> _Tasks = new List<Task>();
     ///<summary>
     /// Use this property to add objects 
     ///</summary>
    public List<Task> ScheduleTasks 
    {
        get { return _Tasks; }
    }
}

服务合同

[ServiceContract(CallbackContract = typeof(ISummitDashboardCallbackContract))]
public interface ISchedulerContract : ISummitDashboardContract
{
    /// <summary>
    /// Sets the named schedule into "run" mode
    /// </summary>
    /// <param name="scheduleName"></param>
    /// <returns></returns>
    [OperationContract()]
    void StartSchedule(string scheduleName);
    /// <summary>
    /// Pauses the currently running schedule
    /// </summary>
    /// <param name="scheduleName"></param>
    [OperationContract()]
    void PauseSchedule(string scheduleName);
    /// <summary>
    /// Removes the named schedule from "run" mode
    /// </summary>
    /// <param name="scheduleName"></param>
    /// <returns></returns>
    [OperationContract()]
    void StopSchedule(string scheduleName);
    /// <summary>
    /// Flips the "active" state of the task with the named id
    /// </summary>
    /// <param name="scheduleName"></param>
    /// <param name="Id"></param>
    [OperationContract()]
    void ToggleTaskState(string scheduleName, string Id);
    /// <summary>
    /// Flips the "active" state of the action with the named id
    /// </summary>
    /// <param name="scheduleName"></param>
    /// <param name="Id"></param>
    /// <returns></returns>
    [OperationContract()]
    void ToggleActionState(string scheduleName, string Id);
    /// <summary>
    /// Returns the information to build the tree list in the dashboard
    /// </summary>
    /// <returns></returns>
    [OperationContract()]
    Schedule[] GetScheduleObjects();
    /// <summary>
    /// Returns the events of the scheduler
    /// </summary>
    /// <returns></returns>
    [OperationContract()]
    SchedulerEvent[] GetSchedulerEvents(int startIndex, int count, int eventLogEntryType);
}