Question

我使用LinqToSql作为ORM。我有一个包含以下代码的表单：

public partial class frmBarcodeList : Form
{

    private ConnectionStringSettings connectionString = ConfigurationManager.ConnectionStrings["myconn"];
    private DatabaseContext _context; 

    public frmBarcodeList()
        {
            _context = new DatabaseContext(connectionString.ConnectionString);
            InitializeComponent();               
        }    
}

在按钮处理程序中，点击我拨打GetInfoFromDataBase。这是问题方法：

private List<TicketInfo> GetInfoFromDataBase()
        {
            try
            {
                var oids = GetSelectedEvents();

                List<Order> orders = new List<Order>();
                List<TicketInfo> data = new List<TicketInfo>();
                foreach (var oid in oids)
                {
                    orders.AddRange(_context.Orders.Where(o => o.ScheduleId == oid && o.IsPayed.Value).ToList());
                }

                foreach (var order in orders)
                {
                    foreach (var detail in order.OrderDetails) ***line 158**
                    {
                        var checkSum = CalculateChecksum(detail.BarCode);
                        TicketInfo info = new TicketInfo();
                        info.Firstname = order.SiteUser.FirstName;
                        info.LastName = order.SiteUser.LastName;
                        info.Email = order.SiteUser.Email;
                        info.Phone = order.SiteUser.PhoneNumber;
                        info.Barcode = string.Format("{0}{1}", detail.BarCode, checkSum);
                        info.FileName = RemoveInvalidFilePathCharacters(string.Format("{0}_{1}", order.EventSchedule.BaseEvent.Name,
                                                                                      order.EventSchedule.RecurrenceStart), "");
                        data.Add(info);
                    }
                }
                return data;
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message + "\n" + e.StackTrace);
            }

            return null;
        }

我收到错误：

---------------------------

---------------------------
Specified cast is not valid.
   at System.Data.SqlClient.SqlBuffer.get_Int32()

   at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)

   at Read_OrderDetail(ObjectMaterializer`1 )

   at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()

   at System.Data.Linq.EntitySet`1.Load()

   at System.Data.Linq.EntitySet`1.GetEnumerator()

   at DT.KazBilet2.BarcodeChecker.frmBarcodeList.GetInfoFromDataBase() in C:\Users\Макс\Documents\Visual Studio 2010\Projects\DT.KazBilet2\branches\NewDesk\DT.KazBilet2.BarcodeChecker\frmBarcodeList.cs:line 158
---------------------------
ОК   
---------------------------

为什么我收到此错误？
感谢。

Answer 1

使用Linq2SQL时，在SqlClient方法中键入强制转换错误（几乎）总是由于模型错误。

我会检查模型是否与数据库一致，尤其是模型中的int字段（get_Int32给出错误）对应于数据库中的实际整数字段。

指定的强制转换在foreach中无效

1 个答案: