Question

我使用EF 6.0并在context.SaveChanges（）上收到此错误（非可空成员的空值。成员：'详细信息'）。该值不为null，但EF仍在抱怨它是：

Non-nullable rror

这适用于两个“CrashDump”对象。

为什么会这样？

编辑：

以下是所有相关代码：

try
{
    if (Uri.CheckHostName(computer) != UriHostNameType.Unknown)
    {
        Ping pingSender = new Ping();
        PingOptions pingOptions = new PingOptions();

        pingOptions.DontFragment = true;
        byte[] buffer = Encoding.ASCII.GetBytes("abcde");
        int timeout = 1;
        PingReply pingReply = pingSender.Send(computer, timeout, buffer, pingOptions);

        string uncPath = String.Format("\\\\{0}\\c$\\windows\\minidump", computer);

        if (pingReply.Status == IPStatus.Success)
        {
            Computer computerObj = (from c in context.Computers
                                    where c.Name == computer
                                    select c).First();
            List<CrashDump> dumps = computerObj.Dumps;

            Process bsodViewProcess = new Process();
            bsodViewProcess.StartInfo.UseShellExecute = false;
            bsodViewProcess.StartInfo.Arguments = 
                string.Format("/loadfrom 1 /minidumpfolder \\\\{0}\\c$\\windows\\minidump /sxml dumps.xml", computer);
            bsodViewProcess.StartInfo.FileName = "BlueScreenView.exe";

            bsodViewProcess.Start();
            bsodViewProcess.WaitForExit();

            XDocument xDoc = XDocument.Load("dumps.xml");

            List<CrashDumpDetails> lstDumpDetails =
                (from dump in xDoc.Element("crash_list").Elements("item")
                    select new CrashDumpDetails
                    {
                        DumpFile = dump.Element("dump_file").Value,
                        CrashTime = dump.Element("crash_time").Value,
                        BugCheckString = dump.Element("bug_check_string").Value,
                        BugCheckCode = dump.Element("bug_check_code").Value,
                        Parameter1 = dump.Element("parameter_1").Value,
                        Parameter2 = dump.Element("parameter_2").Value,
                        Parameter3 = dump.Element("parameter_3").Value,
                        Parameter4 = dump.Element("parameter_4").Value,
                        CausedByDriver = dump.Element("caused_by_driver").Value,
                        CausedByAddress = dump.Element("caused_by_address").Value,
                        FileDescription = dump.Element("file_description").Value,
                        ProductName = dump.Element("product_name").Value,
                        Company = dump.Element("company").Value,
                        FileVersion = dump.Element("file_version").Value,
                        Processor = dump.Element("processor").Value,
                        CrashAddress = dump.Element("crash_address").Value,
                        StackAddress1 = dump.Element("stack_address_1").Value,
                        StackAddress2 = dump.Element("stack_address_2").Value,
                        StackAddress3 = dump.Element("stack_address_3").Value,
                        ComputerName = dump.Element("computer_name").Value,
                        FullPath = dump.Element("full_path").Value,
                        ProcessorsCount = dump.Element("processors_count").Value,
                        MajorVersion = dump.Element("major_version").Value,
                        MinorVersion = dump.Element("minor_version").Value,
                        DumpFileSize = dump.Element("dump_file_size").Value,
                        DumpFileTime = dump.Element("dump_file_time").Value
                    }).ToList();

            foreach (var file in Directory.GetFiles(String.Format("\\\\{0}\\c$\\windows\\minidump", computer)))
            {
                Console.WriteLine(String.Format("\t{0}", file));

                string fileName = Path.GetFileName(file);
                DateTime lastWriteTime = File.GetLastWriteTime(file);

                var existingDump = from d in dumps
                                    where d.FileName == Path.GetFileName(file)
                                    where d.Time.Truncate(TimeSpan.FromSeconds(1)) 
                                            == File.GetLastWriteTime(file).Truncate(TimeSpan.FromSeconds(1))
                                    select d;

                if (existingDump.Count() == 0)
                {
                    CrashDump dump = new CrashDump();
                    dump.FileName = Path.GetFileName(file);
                    dump.Time = File.GetLastWriteTime(file);

                    if (lstDumpDetails.Count > 0)
                    {
                        dump.Details = lstDumpDetails
                            .Where(d => Path.GetFileName(d.DumpFile) == dump.FileName)
                            .FirstOrDefault();
                    }

                    dumps.Add(dump);
                }
            }

            computerObj.Dumps = dumps;

            context.SaveChanges();
        }
    }
}
catch
{

}

Answer 1

这是合理的，因为在非可空字段中，您尝试保存空值。你可以解决这个问题，让你在数据库中的字段可以为空，然后更新你的模型。

Answer 2

问题可能正在发生，因为您使用dump.Details设置FirstOrDefault()的值，当结果集合中不包含任何元素时会导致null。

检查该方案并为其指定一个值，以确保不会发生。

为什么我收到非可空成员的＆＃34; Null值＆＃34;错误？

2 个答案: