c# - 无法在 LINQ to Entities 查询中构造实体或复杂类型“ ”

Question

可能重复：
无法在 LINQ to Entities 查询中构造实体

   var tasks = from i in data.Incidents
                    join a in data.Accounts on i.CustomerID equals a.Acct_CID
                    select new Tasks()
                    {

                        creator_id = a.ID,
                        start_date = i.DateOpened,
                        end_date = i.DateCLosed,
                        product_code = i.ProductCode,
                        install_type = i.InstallType,
                        os = i.OSType,
                        details = i.Description,
                        solution = i.Solution,
                        creator_name = i.TechID,
                        category = i.Title,
                        text = "Ticket for" + " " + i.Name,
                        status_id = 7
                    };

        foreach (var task in tasks)
            data.Tasks.Add(task);
        data.SaveChanges();

 public class Incidents
    {
        [Key]
        public int IncidentID { get; set; }
        public string CustomerID { get; set; }
        public string ProductCode { get; set; }
        public string TechID { get; set; }
        public DateTime DateOpened { get; set; }
        public DateTime DateCLosed { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string Solution { get; set; }
        public string Name { get; set; }
        public string OSType{ get; set; }
        public string InstallType { get; set; }
        public string AddOnSoftware { get; set; }
        public string ScreenShare { get; set; }
    }

当我尝试迭代时给我一个错误，我希望得到一些帮助

Answer 1

在 Linq-to-Entities 中，您只能投影到匿名类型或常规类。您不能投影到现有的实体类型。你可以像这样使用 linq-to-objects

var tasks = (from i in data.Incidents
            join a in data.Accounts on i.CustomerID equals a.Acct_CID
             select new
             {
               creator_id = a.ID,
               start_date = i.DateOpened,
               end_date = i.DateCLosed
              // ...
             }).AsEnumerable().Select(x => new Tasks {
               creator_id = x.creator_id,
               start_date = x.start_date,
               end_date = x.end_date              
             }).ToList();