实体或复杂类型'不能在LINQ构建以查询实体

Question

可能重复：
The entity cannot be constructed in a LINQ to Entities query

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; } 
    } 

给我一个错误，当我尝试迭代，我希望对此有所帮助

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。你可以使用LINQ到对象，像这样

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();