ObjectContext实例已被处置，不能再用于需要连接的操作。 -适用于实体

Question

以下是我的实体。

public class Expense
{
   [Key]
   [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int ExpenseId { get; set; }

   [Required]
   public int CategoryId{ get; set; }
   [ForeignKey("CategoryId")]
   public virtual Category Category { get; set; }

   public virtual List<EditedExpense> EditedExpenses { get; set; }
}
public class EditedExpense
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int EditedExpenseId { get; set; }

    [Required]
    public int CategoryId{ get; set; }
    [ForeignKey("CategoryId")]
    public virtual Category Category { get; set; }

    public int ExpenseId { get; set; }

}
public class Category
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int CategoryId{ get; set; }

    public string Title

    public virtual List<Expense> Expenses { get; set; }
    public virtual List<EditedExpense> EditedExpenses { get; set; }
}

我已使用此代码获取所有Expanses和EditedExpanses

  var expenses = db.Expenses.Include(exp => exp.EditedExpenses).Include(exp => exp.Category);
   return View(expenses.ToList());

现在，我想使用如下所示的两个foreach循环遍历所有Expanses和它们的EditedExpanse，但是当它尝试获取EditedExpense的Category时，它会抛出异常：

foreach(exp in expansesList)
{
    foreach(editedExp in exp.EditedExpanses)
    {
       <text>@editedExp.Category.Title</text>
    }
}

Answer 1

var expenses = db.Expenses
                 .Include(exp => exp.EditedExpenses)
                 .Include(exp => exp.Category);

这包括Expense的Category属性，而不是EditExpense 。

采用：

var expenses = db.Expenses
                 .Include(exp => exp.EditedExpenses.Select(z => z.Category));

编辑：只是为了澄清您所拥有的异常：您当前正在使用延迟加载，因此一旦处理了EF上下文，就不能延迟加载导航属性。 附带说明一下，我总是建议停用延迟加载。 参见https://stackoverflow.com/a/21379510/870604