c# - 使用 Linq 查询计算符合条件的孙元素

Question

我正在尝试确定当前用户是否对ProjectDoc. 此查询给我一个值 1。ProjectDocVote表中没有与UserID. ViewBag.CurrentUserID值是正确的。

 var count = Model.Project.ProjectDoc
       .Where(a => a.Current == true && a.DocType == "Cover")
       .Select(v => v.ProjectDocVote
              .SingleOrDefault(u => u.UserID == ViewBag.CurrentUserID)
       )
       .Count();

如何修复此查询？

Answer 1

将Select和SingleOrDefault替换为Any：

var hasVoted = Model.Project.ProjectDoc
                    .Where(a => a.Current == true && a.DocType == "Cover")
                    .Any(v => v.ProjectDocVote
                               .Any(u => u.UserID == ViewBag.CurrentUserID));

Answer 2

var count = Model.Project.ProjectDoc
   .Where(a => a.Current == true 
            && a.DocType == "Cover"
            && a.ProjectDocVote.Any(v => v.UserID == ViewBag.CurrentUserID))
   .Count():