linq 查询中未处理的异常

Question

描述：进程因未处理的异常而终止。 异常信息：System.InvalidOperationException 堆栈：在 System.Data.Linq.Table1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].CheckReadOnly()
at System.Data.Linq.Table1[[System._Canon, mscorlib, 版本=4.0.0.0，文化=中性， PublicKeyToken=b77a5c561934e089]].DeleteOnSubmit(System._Canon) 在 ReportSender.EmailReportApp.Execute() 在 System.Threading.ThreadHelper.ThreadStart_Context(System.Object) 在 System.Threading.ExecutionContext.Run（System.Threading.ExecutionContext， System.Threading.ContextCallback，System.Object，布尔值）在 System.Threading.ExecutionContext.Run（System.Threading.ExecutionContext， System.Threading.ContextCallback，System.Object）在 System.Threading.ThreadHelper.ThreadStart()

尝试删除以下查询中的记录时出现上述错误： 这个错误到底是什么意思，我该如何解决？

private void Execute()
{
    try
    {
        // Check for a new record
        DataClasses1DataContext dc = new DataClasses1DataContext();

        foreach (var item in dc.reportsSent1s)
        {
            string matchedCaseNumber = item.CaseNumberKey;

            (new MyReportRenderer()).RenderTest(matchedCaseNumber);

            dc.reportsSent1s.DeleteOnSubmit(item);
            dc.SubmitChanges();
        }   
    }
    catch (ThreadAbortException ex)
    {
        _log.WriteEntry(ex.StackTrace.ToString());
    }
}

其余代码如下：

public class MyReportRenderer
{
    private rs2005.ReportingService2005 rs;
    private rs2005Execution.ReportExecutionService rsExec;

    public void RenderTest(String matchedCaseNumber)
    {
        string HistoryID = null;
        string deviceInfo = null;
        string encoding = String.Empty;
        string mimeType = String.Empty;
        string extension = String.Empty;
        rs2005Execution.Warning[] warnings = null;
        string[] streamIDs = null;

        rs = new rs2005.ReportingService2005();
        rsExec = new rs2005Execution.ReportExecutionService();
        rs.Credentials = System.Net.CredentialCache.DefaultCredentials;
        rsExec.Credentials = System.Net.CredentialCache.DefaultCredentials;
        rs.Url = "http://***.**.***.**/ReportServer_DEVELOPMENT/ReportService2005.asmx";
        rsExec.Url = "http://***.**.***.**/ReportServer_DEVELOPMENT/ReportExecution2005.asmx";

        try
        {
            // Load the selected report.
            rsExec.LoadReport("/LawDept/LawDeptTIC", HistoryID);

            // Set the parameters for the report needed.

            rs2005Execution.ParameterValue[] parameters = new rs2005Execution.ParameterValue[1];
            parameters[0] = new rs2005Execution.ParameterValue();
            parameters[0].Name = "CaseNumberKey";
            parameters[0].Value = matchedCaseNumber;

            rsExec.SetExecutionParameters(parameters, "en-us");

            // get pdf of report 
            Byte[] results = rsExec.Render("PDF", deviceInfo,
            out extension, out encoding,
            out mimeType, out warnings, out streamIDs);

            //pass paramaters for email
            DataClasses1DataContext db = new DataClasses1DataContext();

            var matchedBRT = (from c in db.GetTable<vw_ProductClientInfo>()
                              where c.CaseNumberKey == matchedCaseNumber
                              select c.BRTNumber).SingleOrDefault();

            var matchedAdd = (from c in db.GetTable<vw_ProductClientInfo>()
                              where c.CaseNumberKey == matchedCaseNumber
                              select c.Premises).SingleOrDefault();

            //send email with attachment
            MailMessage message = new MailMessage("Rts@acmets.com", "gge.grer@gmail.com", "Report for BRT # " + matchedAdd, "Attached if the Tax Information Certificate for the aboved captioned BRT Number");
            MailAddress copy = new MailAddress("cts@gmail.com");
            message.CC.Add(copy);
            SmtpClient emailClient = new SmtpClient("***.**.***.**");
            message.Attachments.Add(new Attachment(new MemoryStream(results), String.Format("{0}" + matchedBRT + ".pdf", "BRT")));
            emailClient.Send(message);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

Answer 1

看起来 LINQ to SQL 正在检查表是否为只读表，并且正在识别表是只读的并因此抛出（您不能从只读表中删除）。因此，您需要调查为什么 LINQ to SQL 认为该表是只读的。你的桌子上有主键吗？我知道没有一个是 LINQ to SQL 认为一个表是只读的（LINQ to SQL 需要它的identity map）的常见原因。如果这不起作用，George Johnston 的suggestion 尝试将调用移至循环外的SubmitChanges 是一个好方法；在表上获取枚举器可能会在上下文中激活只读锁，这就是 CheckReadOnly 在调用提交时失败的原因。