Develop Reference

System.IO.FileNotFound when passing file path value to OpenXML GetCellValue()

When I pass the value from the OpenFilePicker() method back to the button click method, I can utilize a debug string and ensure that the value is not null.
However, when I pass it to the GetCellValue() method, a 'FileNotFound' exception is thrown. Utilizing a debug statement here also shows that the value is not null and returns a valid file path of "C:\Test.xlsx".
Tried changing file permissions to RWX for all, attempted different folder locations. All permissions and folders seem to have the same issue.
public async void FileSelectButton_ClickAsync(object sender, RoutedEventArgs e)
{
string filePath = await openFilePicker();
//Debug.WriteLine("result:: " + filePath);
GetCellValue(filePath, "Sheet1", "A1");
}
public async Task<string> openFilePicker()
{
var archerReportPicker = new
Windows.Storage.Pickers.FileOpenPicker();
archerReportPicker.ViewMode =
Windows.Storage.Pickers.PickerViewMode.Thumbnail;
archerReportPicker.SuggestedStartLocation =
Windows.Storage.Pickers.PickerLocationId.Downloads;
archerReportPicker.FileTypeFilter.Add(".xlsx");
archerReportPicker.FileTypeFilter.Add(".xls"); // Default extensions
Windows.Storage.StorageFile archerReport = await archerReportPicker.PickSingleFileAsync(); //Get file
if (archerReport != null)
{
// Application now has read/write access to the picked file
this.fileTextBox.Text = archerReport.Name; // Load it up and throw the data in the textbox.
var filePath = archerReport.Path;
return filePath;
}
else
{
this.fileTextBox.Text = "";
return null;
}
}
public static string GetCellValue(string fileName, string sheetName, string addressName)
{
string value = null;
// Open the spreadsheet document for read-only access.
using (SpreadsheetDocument document = SpreadsheetDocument.Open(fileName, false)) //Line where exception is thrown
{...}
Throws System.IO.FileNotFound Exception as opposed to opening valid file path.
The issue also occurs when filePath or fileName is defined using const string '#c:\test.xlsx'

The short answer to this question is here:
https://blogs.msdn.microsoft.com/wsdevsol/2012/12/04/skip-the-path-stick-to-the-storagefile/
The gist of it is that in UWP, Storage Pickers return a non-filesystem bound Windows.Storage object. You can glean the filesystem path from the object, but because you are performing an operation on a secondary object, the fact that the user gave permissions for the first object does not apply to the second, resulting in an Access Denied condition when attempting to open the file - even if NTFS permissions allow 'Everyone' access.
This can be confirmed by monitoring the application using Process Monitor from SystemInternals.
If I discover a work-around to this issue, I will update this answer, but I will likely move away from UWP back towards a Windows Forms Application to avoid this issue entirely.

Why does my file sometimes disappear in the process of reading from it or writing to it?

I have an app that reads from text files to determine which reports should be generated. It works as it should most of the time, but once in awhile, the program deletes one of the text files it reads from/writes to. Then an exception is thrown ("Could not find file") and progress ceases.
Here is some pertinent code.
First, reading from the file:
List<String> delPerfRecords = ReadFileContents(DelPerfFile);
. . .
private static List<String> ReadFileContents(string fileName)
{
List<String> fileContents = new List<string>();
try
{
fileContents = File.ReadAllLines(fileName).ToList();
}
catch (Exception ex)
{
RoboReporterConstsAndUtils.HandleException(ex);
}
return fileContents;
}
Then, writing to the file -- it marks the record/line in that file as having been processed, so that the same report is not re-generated the next time the file is examined:
MarkAsProcessed(DelPerfFile, qrRecord);
. . .
private static void MarkAsProcessed(string fileToUpdate, string
qrRecord)
{
try
{
var fileContents = File.ReadAllLines(fileToUpdate).ToList();
for (int i = 0; i < fileContents.Count; i++)
{
if (fileContents[i] == qrRecord)
{
fileContents[i] = string.Format("{0}{1} {2}"
qrRecord, RoboReporterConstsAndUtils.COMPLETED_FLAG, DateTime.Now);
}
}
// Will this automatically overwrite the existing?
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
}
catch (Exception ex)
{
RoboReporterConstsAndUtils.HandleException(ex);
}
}
So I do delete the file, but immediately replace it:
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
The files being read have contents such as this:
Opas,20170110,20161127,20161231-COMPLETED 1/10/2017 12:33:27 AM
Opas,20170209,20170101,20170128-COMPLETED 2/9/2017 11:26:04 AM
Opas,20170309,20170129,20170225-COMPLETED
Opas,20170409,20170226,20170401
If "-COMPLETED" appears at the end of the record/row/line, it is ignored - will not be processed.
Also, if the second element (at index 1) is a date in the future, it will not be processed (yet).
So, for these examples shown above, the first three have already been done, and will be subsequently ignored. The fourth one will not be acted on until on or after April 9th, 2017 (at which time the data within the data range of the last two dates will be retrieved).
Why is the file sometimes deleted? What can I do to prevent it from ever happening?
If helpful, in more context, the logic is like so:
internal static string GenerateAndSaveDelPerfReports()
{
string allUnitsProcessed = String.Empty;
bool success = false;
try
{
List<String> delPerfRecords = ReadFileContents(DelPerfFile);
List<QueuedReports> qrList = new List<QueuedReports>();
foreach (string qrRecord in delPerfRecords)
{
var qr = ConvertCRVRecordToQueuedReport(qrRecord);
// Rows that have already been processed return null
if (null == qr) continue;
// If the report has not yet been run, and it is due, add i
to the list
if (qr.DateToGenerate <= DateTime.Today)
{
var unit = qr.Unit;
qrList.Add(qr);
MarkAsProcessed(DelPerfFile, qrRecord);
if (String.IsNullOrWhiteSpace(allUnitsProcessed))
{
allUnitsProcessed = unit;
}
else if (!allUnitsProcessed.Contains(unit))
{
allUnitsProcessed = allUnitsProcessed + " and "
unit;
}
}
}
foreach (QueuedReports qrs in qrList)
{
GenerateAndSaveDelPerfReport(qrs);
success = true;
}
}
catch
{
success = false;
}
if (success)
{
return String.Format("Delivery Performance report[s] generate
for {0} by RoboReporter2017", allUnitsProcessed);
}
return String.Empty;
}
How can I ironclad this code to prevent the files from being periodically trashed?
UPDATE
I can't really test this, because the problem occurs so infrequently, but I wonder if adding a "pause" between the File.Delete() and the File.WriteAllLines() would solve the problem?
UPDATE 2
I'm not absolutely sure what the answer to my question is, so I won't add this as an answer, but my guess is that the File.Delete() and File.WriteAllLines() were occurring too close together and so the delete was sometimes occurring on both the old and the new copy of the file.
If so, a pause between the two calls may have solved the problem 99.42% of the time, but from what I found here, it seems the File.Delete() is redundant/superfluous anyway, and so I tested with the File.Delete() commented out, and it worked fine; so, I'm just doing without that occasionally problematic call now. I expect that to solve the issue.

// Will this automatically overwrite the existing?
File.Delete(fileToUpdate);
File.WriteAllLines(fileToUpdate, fileContents);
I would simply add an extra parameter to WriteAllLines() (which could default to false) to tell the function to open the file in overwrite mode, and not call File.Delete() at all then.
Do you currently check the return value of the file open?
Update: ok, it looks like WriteAllLines() is a .Net Framework function and therefore cannot be changed, so I deleted this answer. However now this shows up in the comments, as a proposed solution on another forum:
"just use something like File.WriteAllText where if the file exists,
the data is just overwritten, if the file does not exist it will be
created."
And this was exactly what I meant (while thinking WriteAllLines() was a user defined function), because I've had similar problems in the past.
So, a solution like that could solve some tricky problems (instead of deleting/fast reopening, just overwriting the file) - also less work for the OS, and possibly less file/disk fragmentation.

Save and delete Excel file saved using HttpPostedFileBase

I am uploading an Excel file and extracting data from that and saving it into a database. I am using MVC4 .NET Framework. This is my code from class:
public static void Upload(HttpPostedFileBase File)
{
NIKEntities1 obj = new NIKEntities1();
MyApp = new Excel.Application();
MyApp.Visible = false;
string extension = System.IO.Path.GetExtension(File.FileName);
string pic = "Excel" + extension;
string path = System.IO.Path.Combine(System.Web.HttpContext.Current.Server.MapPath("~/Excel"), pic);
File.SaveAs(path);
MyBook = MyApp.Workbooks.Open(path);
MySheet = (Excel.Worksheet)MyBook.Sheets[1]; // Explicit cast is not required here
int lastRow = MySheet.Cells.SpecialCells(Excel.XlCellType.xlCellTypeLastCell).Row;
List<Employee> EmpList = new List<Employee>();
for (int index = 2; index <= lastRow; index++)
{
System.Array MyValues = (System.Array)MySheet.get_Range("A" +
index.ToString(), "B" + index.ToString()).Cells.Value;
EmpList.Add(new Employee
{
BatchID = MyValues.GetValue(1, 1).ToString(),
BatchName = MyValues.GetValue(1, 2).ToString()
});
}
for (int i = 0; i < EmpList.Count; i++)
{
int x=obj.USP_InsertBatches(EmpList[i].BatchID, EmpList[i].BatchName);
}
}
}
class Employee
{
public string BatchID;
public string BatchName;
}
This code is working perfectly the first time but next time it says that file is currently in use. So I thought of deleting the file at the end of code using the following line:
File.Delete(path);
But this line threw error:
HttpPostedFileBase does not contain definition for Delete
Also, if I don't write this line and try to execute code again it says that it can't save because a file exists with same name and could not be replaced because it is currently in use.
What should I do to get rid of this:
(File.Delete()) Error
Any other way of accessing the Excel file which I am receiving without saving will also be very helpful because I have to just access the data one time.

The File you use there is your variable that is the input parameter of your method. That parameter is of type HttpPostedFileBase and that type has no instance methods (nor static ones for that matter) that allow you to delete that File instance.
You are probably looking for the static Delete method on the File type that is in the System.IO namespace.
A quickfix would be to be explicit about which File you mean:
System.IO.File.Delete(path);
You might want to consider a different naming guideline for your variables though. In c# we tend to write variables starting with a lower case letter. Almost all types in the framework start with an Uppercase letter. Which makes it easier to distinguish the thing file and the type File.
Do notice that a file can only be deleted if it is closed by all processes and all file handles are cleared by the filesystem. In your case you have to make sure Excel closed the file and released it's handles. If you have the search indexer running or a rough virus scanner you might have to try a few times before giving up.
I normally use this code:
// make sure here all Ole Automation servers (like Excel or Word)
// have closed the file (so close the workbook, document etc)
// we iterate a couple of times (10 in this case)
for(int i=0; i< 10; i++)
{
try
{
System.IO.File.Delete(path);
break;
} catch (Exception exc)
{
Trace.WriteLine("failed delete {0}", exc.Message);
// let other threads do some work first
// http://blogs.msmvps.com/peterritchie/2007/04/26/thread-sleep-is-a-sign-of-a-poorly-designed-program/
Thread.Sleep(0);
}
}

From what I can tell, you are opening Excel, reading the file but never closing the Excel.
Add:
MyApp.Workbooks.Close();
MyApp.Quit();
at the end of the Upload function. Even better, wrap whole code you got in
try{
//here goes your current code
}
catch(Exception e)
{
//manage exception
}
finally
{
MyApp.Workbooks.Close();
MyApp.Quit();
}
You initialize MyApp outside try catch block, then whatever happens close the file.

System.IO.IOException creating File

I have an Error if I write something in a newly created File.
This is my code:
private void ButtonClick(object sender, EventArgs e)
{
Button b = (Button)sender;
string inputKey = b.Text;
for (int i = 0; i < tunes.Length; i++)
{
if (b.Text == tun[i].TuneName)
{
Console.Beep(tun[i].Frequency, 200);
Input.Items.Add(b.Text);
Output.Items.Add(tun[i].TuneName);
if (startButtonPressed == true)
{
filename2 = musicFileName + ".csv";
File.WriteAllText(filename2, tun[i].TuneName);
RecordList.Items.Add(tun[i].TuneName);
}
}
}
}
The Error comes at Line : File.WriteAllText()...
It says that the File can not be used, because it's used by an another process,but I havent opened any File.

I'd use a Filestream generated by File.Create(), but I'd make the loop inside the using statement, so you ensure that all ressources will be released at the end (that's why you use using).
using (FileStream fs = File.Create(Path.Combine(musicFileName, ".csv")))
{
foreach (tun in tunes)
{
fs.Write(tun.TuneName);
}
}
The problem you were actually having is, that you were never closing your file. You should look up using-keyword. It can used only with classes implementing the IDisponsable Interface. It then will call disponse() at the end of the using block and all ressources will be released, eg the file will be closed.

You need to make sure that the variable filename2 contains a valid path like C:\temp\myfile and not just myfile additionally you might need to run visual studio with elevated privilege if the location is not accessible otherwise.

You could also use streamwriter...
using (StreamWriter writer =new StreamWriter(musicFileName + ".csv";))
{
writer.Write(tun[i].TuneName);
}

How do I prevent System.IO.Directory.Delete(pathtodelete, true) from giving me a "Directory is not empty" error?

I'm kinda new to working with C# .NET's System.IO namespace. So please forgive me for some basic questions.
I am writing an online interface that will allow a site owner to modify files and directories on the server.
I have gotten inconsistent performance out of System.IO.Directory.Delete(PathToDelete, true);. Sometimes it works great, sometimes it throws an error. My controller looks like this:
public ActionResult FileDelete(List<string> entity = null)
{
if (entity != null)
{
if (entity.Count() > 0)
foreach (string s in entity)
{
string CurrentFile = s.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
string FileToDelete = Server.MapPath(CurrentFile);
bool isDir = (System.IO.File.GetAttributes(FileToDelete) & FileAttributes.Directory) == FileAttributes.Directory;
if (isDir)
{
if (System.IO.Directory.Exists(FileToDelete))
{
//Problem line/////////////////////////////////
System.IO.Directory.Delete(FileToDelete, true);
}
}
else
{
if (System.IO.File.Exists(FileToDelete))
{
System.IO.File.Delete(FileToDelete);
string ThumbConfigDir = ConfigurationManager.AppSettings["ThumbnailSubdirectory"];
string ThumbFileToDelete = Path.GetDirectoryName(FileToDelete) + Path.DirectorySeparatorChar + ThumbConfigDir + Path.DirectorySeparatorChar + Path.GetFileName(FileToDelete);
if (System.IO.File.Exists(ThumbFileToDelete))
{
System.IO.File.Delete(ThumbFileToDelete);
}
}
}
}
}
return Redirect(HttpContext.Request.UrlReferrer.AbsoluteUri.ToString());
}
Sometimes, I get an error when tring to delete directories that says:
The directory is not empty.
Description: An unhandled exception occurred during the execution of the current
web request. Please review the stack trace for more information about the error
and where it originated in the code.
Exception Details: System.IO.IOException: The directory is not empty.
Source Error:
Line 137: if (System.IO.Directory.Exists(FileToDelete))
Line 138: {
Line 139: System.IO.Directory.Delete(FileToDelete, true);
Line 140: }
Line 141: }
I'm not sure what kind of defensive coding I can implement to avoid get errors like these. Any thoughts? Am I missunderstanding what it means to set recursive to true by saying System.IO.Directory.Delete(FileToDelete, true);?

If there's a file that's in use, the Delete won't empty the directory, and then will fail when it will try to delete the directory.
Try using FileInfo instead of the static methods, and use Refresh after you do any action on the file. (or DirectoryInfo for direcotries)
Similar problem

In general you just have to expect this sort of exceptions from file/folder manipulation code. There is large number of reasons why it could happen - some file in use, some process have working folder set to the directory, some files are not visible to your process due to permissions and so on.
Process monitor ( http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx) likely will show what causes the problem.
One of common reason if you create folder yourself for your temporary files and then try to delete it is to forget to dispose Stream objects related to files in such folder (could be indirect links by Reader and Writer objets, XmlDocument).