Question

public IEnumerable<Models.Comment> GetUserComments()
{
    return List<Comment>
    {
        new Comment
        {
            CommentFor = "ee",
            DateAdded = DateTime.Now,
            CommentText = "aaaa",
            Location = new Location
            {
                Name = "Location Name",
                Country = new Country
                {
                    Name="Israel"
                },
                State=new State { Name="TelAviv" }
            }
        } 

    };
}

你可以帮我纠正Linq查询吗？

我需要使用Entity Framework 4从数据库中获取价值。
我确实喜欢这个

         public IEnumerable<Models.Comment> GetUserComments()
    {
         var comment = (from u in context.Comments
                       where u.UserID == userId
                       select new Comment
                       {
                           //Location = context.Locations.FirstOrDefault(x => x.locationid == u.LocationID).name,
                           Location = (from l in context.Locations
                                       where l.LocationID == u.LocationID
                                       select new Location
                                       {
                                           Name = l.Name,
                                           State = (
                                                 from s in context.States
                                                 where (s.StateID == l.StateID)
                                                 select new State { Name  = s.Name }
                                                 ).FirstOrDefault()

                                       }
                                       ).FirstOrDefault(),
                           CommentFor = "bs",
                           DateAdded = u.DateAdded,
                           CommentText = u.CommentText
                       }
                    ).ToList();
                       }

得到如下错误：

无法在LINQ to Entities查询中构造实体或复杂类型“CGWeb.Models.Repositories.Comment”。

请告诉我我的错误在哪里

Answer 1

                   select new Comment
                   {
                       u.Location //<- remove the u.

Answer 2

u.Location应为Location。

Answer 3

试试这个

var comment = (from u in context.Comments
                           where u.UserID == userId
                           select new Comment
                           {
                               Location = context.Locations.FirstOrDefault(x=>x.LocationID==u.LocationID).Name,                                        
                               CommentFor = "Bb",
                               DateAdded = u.DateAdded,
                               CommentText = u.CommentText
                           }
                        ).ToList();

实体框架4.0与Linq

3 个答案: