對象不能從DBNull轉換爲其他類型。對象無法從DBNull轉換爲其他類型
我有一個以下函數拋出上述錯誤。我正在處理商店程序和C#代碼中的所有空值。
那麼它在哪裏得到這個錯誤?
我可以看到catch塊中的錯誤。但我不明白哪一行在下面的create()獲取錯誤。
public Boolean Create(DataTO DataTO)
{
IDbTrans transaction = null;
IDbCmd IDbCmd;
string EncryptedPassword = Encrypt(DataTO.txtPwd);
Base dataAccCom = null;
try
{
dataAccCom = Factory.Create();
dataAccCom.OpenConnection();
transaction = dataAccCom.BeginTransaction();
IDbCmd = dataAccCom.CreateCommand("sp_Register", true);
dataAccCom.AddParameter(IDbCmd, "op_Id", DbType.Int64, 0, ParameterDirection.Output);
dataAccCom.AddParameter(IDbCmd, "p_dlstTitle", DbType.String, ReplaceNull(DataTO.dlstTitle));
dataAccCom.AddParameter(IDbCmd, "p_txtFirstName", DbType.String, ReplaceNull(DataTO.txtFirstName));
dataAccCom.AddParameter(IDbCmd, "p_txtMiddleName", DbType.String, ReplaceNull(DataTO.txtMiddleName));
dataAccCom.AddParameter(IDbCmd, "p_txtLastName", DbType.String, ReplaceNull(DataTO.txtLastName));
dataAccCom.AddParameter(IDbCmd, "p_txtDob", DbType.DateTime, DataTO.txtDob);
dataAccCom.AddParameter(IDbCmd, "p_txtDesig", DbType.String, ReplaceNull(DataTO.txtDesig));
dataAccCom.AddParameter(IDbCmd, "p_txtOFlatNo", DbType.String, ReplaceNull(DataTO.txtOFlatNo));
dataAccCom.AddParameter(IDbCmd, "p_txtOBuild", DbType.String, ReplaceNull(DataTO.txtOBuild));
dataAccCom.AddParameter(IDbCmd, "p_txtOPost", DbType.String, ReplaceNull(DataTO.txtOPost));
dataAccCom.AddParameter(IDbCmd, "p_txtOArea", DbType.String, ReplaceNull(DataTO.txtOArea));
dataAccCom.AddParameter(IDbCmd, "p_txtOCity", DbType.String, ReplaceNull(DataTO.txtOCity));
dataAccCom.AddParameter(IDbCmd, "p_txtRBuild", DbType.String, ReplaceNull(DataTO.txtRBuild));
dataAccCom.AddParameter(IDbCmd, "p_txtRPost", DbType.String, ReplaceNull(DataTO.txtRPost));
dataAccCom.AddParameter(IDbCmd, "p_txtUserID", DbType.String,ReplaceNull(DataTO.txtUserID));
dataAccCom.AddParameter(IDbCmd, "p_txtPwd", DbType.String, ReplaceNull(EncryptedPassword));
dataAccCom.ExecuteNonQuery(IDbCmd);
DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));
transaction.Commit();
return true;
}
catch (System.Exception ex)
{
if (transaction != null)
{
transaction.Rollback();
}
throw ex;
}
finally
{
transaction = null;
if (dataAccCom != null)
{
dataAccCom.CloseConnection();
}
dataAccCom = null;
IDbCmd = null;
}
}
public string ReplaceNull(string value)
{
if (value == null)
{
return "";
}
else
{
return value;
}
}
public DateTime ReplaceNull(DateTime value)
{
if (value == null)
{
return DateTime.Now;
}
else
{
return value;
}
}
public double ReplaceNull(double value)
{
if (value == null)
{
return 0.0;
}
else
{
return value;
}
}
注意在'double'和'DateTime'是毫無價值的,你的'ReplaceNull'重載。這些類型的值不能爲空,因此也不會傳遞'if(value == null)'條件。 – 2011-05-23 14:35:04
除非它們當然是可空的,但那是另一回事。 – BoltClock 2011-05-23 14:36:07
你有沒有采取這種方法?在Visual Studio中,考慮打破所有異常(Ctrl + Alt + E)並查看實際導致問題的線。 – 2011-05-23 14:36:35