查询模型内部，如何获取特定类中的项目数

Question

我想出了这个：

[NotMapped]
    public int ThreadsInBoard
    {
        get
        {
            ForumContextContainer ctx = new ForumContextContainer();
            int thr = (from p in ctx.BoardSet
                       from x in ctx.ThreadSet
                       where p.BoardID == x.Board.BoardID
                       select p).Count();
        }
    }

我想做的是特定板上的线程数。 该查询实际上返回数据库中每个可能线程的计数并对其进行分配。 以下是涉及的类

    public partial class Board
{
    public int BoardID { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public bool IsVisibleToGuests { get; set; }
    public bool IsLocked { get; set; }

    public Forum Forum { get; set; }
    public ICollection<Thread> Thread { get; set; }
}

    public partial class Thread
{
    public int ThreadID { get; set; }

    public User User { get; set; }
    public ICollection<Post> Post { get; set; }
    public Board Board { get; set; }
    public ICollection<Subscription> Subscription { get; set; }
    public ICollection<Poll> Poll { get; set; }
}

Answer 1

[NotMapped]
    public int ThreadsInBoard
    {
        get
        {
            ForumContextContainer ctx = new ForumContextContainer();
            int thr = ctx.ThreadSet.Count(p => p.BoardID == this.BoardID);
        }
    }

假设此类具有 boardId 属性