'只支持原始類型，枚舉類型和實體類型'

Question

我想，我理解它並且不會有問題。但現在我很困惑。我有以下代碼：

public class ProjectMemberUserRolesElementViewModel 
{ 
    public string AccessType { get; set; } 
    public bool Delete { get; set; } 
    public bool Create { get; set; } 
    public bool Edit { get; set; } 
    public bool Read { get; set; } 
} 


var elements = from i in db.ProjectAccessTypes 
       select new ProjectMemberUserRolesElementViewModel() 
       { 
        AccessType = i.Type, 
        Create = (i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID) != null) ? (from p in i.ProjectMemberAccess where p.ProjectMemberID == ProjectMemberID select p.Create).FirstOrDefault() : false, 
        Delete = (i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID) != null) ? i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Delete).FirstOrDefault() : false, 
        Edit = (i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID) != null) ? i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Edit).FirstOrDefault() : false, 
        Read = (i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID) != null) ? i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Read).FirstOrDefault() : false 
       }; 

爲什麼我得到這個錯誤？這裏的原始類型不在哪裏？

Answer 1

解決方法很簡單：

elements = from i in db.ProjectAccessTypes 
       select new ProjectMemberUserRolesElementViewModel() 
       { 
        AccessType = i.Type, 
        Create = i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Create).FirstOrDefault(), 
        Delete = i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Delete).FirstOrDefault(), 
        Edit = i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Edit).FirstOrDefault(), 
        Read = i.ProjectMemberAccess.Where(p => p.ProjectMemberID == ProjectMemberID).Select(p => p.Read).FirstOrDefault() 
       }; 

Answer 2

非原始類型是您的類型ProjectMemberUserRolesElementViewModel。我假設這種類型不是你的EF模型的一部分，但是你的視圖模型類的一部分。因此，在編譯爲SQL時，EF無法投影到此類型。

解決方案：改爲使用.AsEnumerable（）方法轉到匿名類型，然後將項目轉到您的視圖模型類型。