實現IEnumerable'System.Collections.Generic.List`1'的類型不能在LINQ to Entities查詢中初始化

Question

我想在Linq查詢中創建一些類的對象，但給我一個錯誤，這個問題。

我的查詢是：

List<oneViewModel> workOrderInfoList = (from abc in db.ABC 
    join customer in db.Customers on abc.CustomerId equals customer.CustomerId into customers 
    select new oneViewModel() 
    { 
    CustomerId = abc.CustomerId, 
    OrderNumber = workOrderInfo.OrderNumber, 
    OrderDate = abc.OrderDate, 
    SecondClassList = new List<SecondClass>(), 
    }).ToList(); 

我在AS內部oneViewModel對象定義類的列表。

public class ABC   
{ 
    public DateTime? WorkOrderDate { get; set; } 
    public long CustomerId { get; set; } 

    public string CustomerName { get; set; } 

    public List<SecondClass> SecondClassList { get; set; } 
} 

Answer 1

初始化的secondClass列表您ViewModel構造函數中：

Public oneViewModel() 
{ 
    SecondClassList = new List<SecondClass>(); 
) 

記得從Linq查詢中刪除初始化。

編輯

List<oneViewModel> workOrderInfoList = (from abc in db.ABC 
    join customer in db.Customers on abc.CustomerId equals customer.CustomerId into customers 
    select new oneViewModel() 
    { 
     CustomerId = abc.CustomerId, 
     OrderNumber = workOrderInfo.OrderNumber, 
     OrderDate = abc.OrderDate, 
     SecondClassList = abc.SecondClassList 
    }).ToList(); 

編輯2

你oneViewModel應該是這個樣子：

public class oneViewModel 
{ 
    public oneViewModel 
    { 
     SecondClassList = new List<SecondClass>(); 
    } 

    Public List<SecondClass> SecondClassList { get; set; } 
} 

LINQ查詢應該是這樣的：

List<oneViewModel> workOrderInfoList = (from abc in db.ABC 
join customer in db.Customers on abc.CustomerId equals customer.CustomerId into customers 
select new oneViewModel() 
{ 
    CustomerId = abc.CustomerId, 
    OrderNumber = workOrderInfo.OrderNumber, 
    OrderDate = abc.OrderDate 
}).ToList(); 

現在您將擁有一個oneViewModel對象的列表。

Answer 2

您需要先執行查詢，然後初始化列表，例如：

List<oneViewModel> workOrderInfoList = (from abc in db.ABC 
    join customer in db.Customers on abc.CustomerId equals customer.CustomerId into customers).ToList() 
    Select(n => new oneViewModel() 
    { 
    CustomerId = n.CustomerId, 
    OrderNumber = workOrderInfo.OrderNumber, 
    OrderDate = n.OrderDate, 
    SecondClassList = new List<SecondClass>(), 
    }).ToList();