odata的导航属性问题

Question

我有一个名为ProjectViewModel的视图模型和名为Project的普通模型..所以我通过linq查询填充ProjectViewModel。

但返回错误

  

＆＃39; ObjectContent`1＆＃39;类型无法序列化内容类型的响应主体＆＃39; application / json;的OData = minimalmetadata;流= TRUE;字符集= UTF-8＆＃39;＆＃34;＆＃34;类型＆＃34;：＆＃34; System.InvalidOperationException＆＃34;＆＃34;堆栈跟踪＆＃34;：＆＃34;＆＃34 ;，＆＃34; internalexception＆＃34;：{           ＆＃34;消息＆＃34;：＆＃34;未找到NavigationLink工厂的导航属性＆＃39;订阅＆＃39;来自实体类型＆＃39; SSAStatusService.Domain.ViewModel.ProjectViewModel＆＃39;在实体集＆＃39;项目＆＃39;。尝试在EntitySetConfiguration上调用HasNavigationPropertyLink。\ r \ nParameter name：navigationProperty

以下是我的课程

 public class ProjectViewModel
{
   public String ProjectId { get; set; }

   public String Name { get; set; }

   public List<Subscriptions> Subscriptions { get; set; }

}

public class Subscriptions
{
    public long Id { get; set; }

    [MaxLength(40)]
    public string ProjectId { get; set; }

    public string SubscriptionId { get; set; }
}

var query=from p in DataContext.Project 
      join c in DataContext.Subscriptions on p.ProjectId equals c.ProjectId into subs
      select new ProjectViewModel { 
                                    ProjectId = p.ProjectId,
                                    Name = p.Name,
                                    Subscriptions=subs.ToList()
                                  };