得到「不支持計數」的異常

Question

我正在開發一個Windows Phone 7應用程序，我想自動增加使用代碼優先技術創建的數據庫值。 我嘗試了下面的邏輯來完成這件事，但其造成的異常「計數法不支持」

var c = new AccountEntryModel(); 
Expense exp = new Expense(); 
if (c.Expenses.Count() == 0) 
exp.ExpenseId = 1; 
else 
exp.ExpenseId = c.Expenses.Max<Expense>(b => b.ExpenseId) + 1; 
ExpenseIdTextBox.Text = exp.ExpenseId.ToString(); 

Answer 1

我想你的代碼，並在Windows手機工作得很好7.1

這裏是我的嘗試：

var c = new AccountEntryModel(); 
Expense exp = new Expense(); 
if (c.Expenses.Count() == 0) 
    exp.ExpenseId = 1; 
else 
    exp.ExpenseId = c.Expenses.Max<Expense>(b => b.ExpenseId) + 1; 

這裏是我在我的假設建立在您的代碼上面的類：

public class Expense 
{ 
    public int ExpenseId { get; set;} 
} 

public class AccountEntryModel 
{ 
    public AccountEntryModel() 
    { 
     Expenses = new List<Expense>(); 

     for (int i = 1; i < 10; i++) 
     { 
      Expenses.Add(new Expense { ExpenseId = i }); 
     } 

    } 
    public List<Expense> Expenses { get; set;} 
}