When I open an excel file, a hidden temporary file is generated in the same folder. I can open it with the TotalCommander Viewer, but I always get an IO exception when trying to open with powershell or c#.
new FileStream(#"D:\~$test.xlsx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
System.IO.IOException: 'The process cannot access the file 'D:~$test.xlsx' because it is being used by another process.'
So how can I get the content?
Unfortunately for some reason you can not open the direct file, so I suggest another method when you copy a the file to a temp file, then read it and finally you delete the temp file, this way you can read it, I suppose TotalCommander uses the same method for opening files in Viewer.
static void Main(string[] args)
{
CopyReadAndDelete(#"c:\Documents\~$test.xlsx");
}
static void CopyReadAndDelete(string filePath)
{
var tempFileFullPath = Path.Combine(Path.GetDirectoryName(filePath), Guid.NewGuid().ToString());
File.Copy(filePath, tempFileFullPath);
try
{
using (var sr = new StreamReader(tempFileFullPath))
{
Console.WriteLine(sr.ReadToEnd()); //or do anything with the content
}
}
finally
{
File.Delete(tempFileFullPath);
}
}
Related
My objective is to write some data into an excel.
Here i am opening a file with file stream by exclusive lock (FileMode.Open, FileShare.Read etc., I need to lock the file to restrict others writing into excel while i am processing.) then writing some content into it and finally close the stream, so that other threads can write into this file. I am using EPPlus(5.7.4) version.
The code i am using here is :
public void WriteToExcel()
{
using (var stream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite, FileShare.Read))
using (var excelPackage = new ExcelPackage(stream))
{
DoSomething(excelPackage);
excelPackage.SaveAs(stream);
stream.Close();
}
}
public void DoSomething(ExcelPackage excelPackage)
{
var cell = excelPackage.Workbook.Worksheets[0].Cells[2, 3];
cell.Value = "some value";
}
I put a break point in using statement and opened excel in the middle of execution and it showing a message saying like below which is correct.
But once i finish with execution when i try to open excel file it showing below error message.
We found a problem with some content in Sample.xlsx. Do you want us to try to recover as much as we can? if you trust the source of this book, Click Yes
I tried in different ways but none worked for me, as same error message is displaying. Can someone help me resolving this issue.
The problem is that you're reading from and rewriting to the same file stream simultaneously.
You can test this by changing excelPackage.SaveAs(new FileInfo("Book2.xlsx")); and create a new file - your file will be created without any issues.
You could open your original document, write the changes to a new file, then delete the original file and rename the new file back to the original name:
ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
using (var stream = new FileStream("Book1.xlsx", FileMode.Open, FileAccess.ReadWrite, FileShare.Read))
using (var excelPackage = new ExcelPackage(stream))
{
DoSomething(excelPackage);
excelPackage.SaveAs(new FileInfo("Book2.xlsx"));
}
File.Delete("Book1.xlsx");
File.Move("Book2.xlsx", "Book1.xlsx");
The caveat with this is that if you have multiple things trying to access that file, then they might throw FileNotFound exceptions if they happen to try to open Book1.xlsx after it's delete and before Book2.xlsx is renamed.
That said, if you're dealing with that level of parallelism then you shouldn't be using a Excel file.
Side note: You don't need stream.Close(); as the using block automatically closes the stream.
Below code useful to me, you can refer it.
public void WriteToExcel()
{
string path = #"C:\Use**op\aa.xlsx";
FileInfo file = new FileInfo(path);
ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
using (ExcelPackage package = new ExcelPackage(file))
{
DoSomething(package);
}
}
public void DoSomething(ExcelPackage package)
{
ExcelWorksheet worksheet = package.Workbook.Worksheets[0];
worksheet.Cells[2,4].Value = "some value";
package.Save();
}
My current project uses a direct file path of this excel document to read information off of the excel file. I need to get my project ready for release so I cannot have the project hard code a file path in the form of a string.
I want to embed the Excel File in my resource, which I have done, but know how can I get the file path from Resource, and send a file path to the class which reads the Excel file. The class must be feed a filepath so I was thinking of making a copy of this Excel file, and in the Temp folder then referenceing the file path for the class to read the Excel file.
FileName = #"D:\SomeFolder\ExcelFile.xlsx"; //This is the old code, hard coded
//I need code that is going to make a copy of this file from the Resources and save it somewhere in a temp folder, but then give me
the File path in the form of a string.
string FileName;
// I need the file name to have the directory of this excel that is in the Resource folder
//Call Class to Create XML File and store Data from BIN File Locally on Program
ReadExcel_CreateXML = new ExcelRecorder(FileName);
Something else to think about is that you are probably reading the current files using a FileStream and either a BinaryReader or StreamReader. If that's the case, the consumer of the file could be written to accept an arbitrary Stream instead and then you can create a MemoryStream to pass to the consuming class:
// The resource will be a byte array, I'm just creating a
// byte array manually for example purposes.
var fileData = System.Text.Encoding.UTF8.GetBytes("Hello\nWorld!");
using (var memoryStream = new MemoryStream(fileData))
using (var streamReader = new StreamReader(memoryStream))
{
// Do whatever you need with the file's contents
Console.WriteLine(streamReader.ReadLine());
Console.WriteLine(streamReader.ReadLine());
}
This approach means you won't be cluttering up the client computer with temporary files that you'll need to clean up. It also means your consuming class will become more flexible if you ever need to process data over any other type of Stream.
I'm not sure if this the best solution, but it will work:
1st get the byte[] array of the file in your resources:
byte[] fileByteArray = global::YourProjectNameSpace.Properties.Resources.ExcelFileName
2nd Export the file to a temporary location using this function:
(I got from here: Write bytes to file)
public bool ByteArrayToFile(string _FileName, byte[] _ByteArray)
{
try
{
// Open file for reading
System.IO.FileStream _FileStream =
new System.IO.FileStream(_FileName, System.IO.FileMode.Create,
System.IO.FileAccess.Write);
// Writes a block of bytes to this stream using data from
// a byte array.
_FileStream.Write(_ByteArray, 0, _ByteArray.Length);
// close file stream
_FileStream.Close();
return true;
}
catch (Exception _Exception)
{
// Error
Console.WriteLine("Exception caught in process: {0}",
_Exception.ToString());
}
// error occured, return false
return false;
}
And last access that temporary file like you normally would
Use:
Just create a button in a form and put this code in the button's click event
private void button1_Click(object sender, EventArgs e)
{
byte[] fileByteArray = global::YourProjectNameSpace.Properties.Resources.ExcelFileName;
if (ByteArrayToFile(#"C:\Temp\file.xlsx", fileByteArray))
{
//File was saved properly
}
else
{
//There was an error saving the file
}
}
Hope it works
I'm monitoring a folder for new files, and when the new file is present I read (and save in a txt) the file as following:
FileStream file = File.Open(this.filePath, FileMode.Open, FileAccess.Read);
StreamReader reader = new System.IO.StreamReader(file);
string text = reader.ReadToEnd();
reader.Close();
If I copy/paste in the folder the source file, I receive an IOExcpetion that tells me that the file is used by another process.
If I cut/paste in the folder, all works.
Moreover locking problem happens also If I copy (but also cut in this case)/paste the file from another machine into the monitored folder.
Do you have an idea about what is happening?
There is a safer way to access to the file in order to avoid this type of locks?
Thanks!
Here is a little snippet I do to ensure the file is finished copying or not in use by another process.
private bool FileUploadCompleted(string filename)
{
try
{
using (FileStream inputStream = File.Open(filename, FileMode.Open,
FileAccess.Read,
FileShare.None))
{
return true;
}
}
catch (IOException)
{
return false;
}
}
Then you can implement this before your process logic
while (!FileUploadCompleted(filePath))
{
//if the file is in use it will enter here
//So you could sleep the thread here for a second or something to allow it some time
// Also you could add a retry count and if it goes past the allotted retries you
// can break the loop and send an email or log the file for manual processing or
// something like that
}
How do I open (using c#) a file that is already open (in MS Word, for instance)? I thought if I open the file for read access e.g.
FileStream f= new FileStream('filename', FileMode.Open, FileAccess.ReadWrite);
I should succeed, but I get an exception:
"the process cannot access the file
because it is locked ..."
I know there must be a way to read the file irrespective of any locks placed on it, because I can use windows explorer to copy the file or open it using another program like Notepad, even while it is open in WORD.
However, it seems none of the File IO classes in C# allows me to do this. Why?
You want to set FileAccess=Read and FileShare=ReadWrite. Here is a great article on this (along with an explanation of why):
http://coding.infoconex.com/post/2009/04/How-do-I-open-a-file-that-is-in-use-in-C.aspx
Your code is using the FileAccess.Read*Write* flag. Try just Read.
I know this is an old post. But I needed this and I think this answer can help others.
Copying a locked file the way the explorer does it.
Try using this extension method to get a copy of the locked file.
Usage example
private static void Main(string[] args)
{
try
{
// Locked File
var lockedFile = #"C:\Users\username\Documents\test.ext";
// Lets copy this locked file and read the contents
var unlockedCopy = new
FileInfo(lockedFile).CopyLocked(#"C:\Users\username\Documents\test-copy.ext");
// Open file with default app to show we can read the info.
Process.Start(unlockedCopy);
}
catch (Exception ex)
{
Trace.TraceError(ex.Message);
}
}
Extension method
internal static class LockedFiles
{
/// <summary>
/// Makes a copy of a file that was locked for usage in an other host application.
/// </summary>
/// <returns> String with path to the file. </returns>
public static string CopyLocked(this FileInfo sourceFile, string copyTartget = null)
{
if (sourceFile is null)
throw new ArgumentNullException(nameof(sourceFile));
if (!sourceFile.Exists)
throw new InvalidOperationException($"Parameter {nameof(sourceFile)}: File should already exist!");
if (string.IsNullOrWhiteSpace(copyTartget))
copyTartget = Path.GetTempFileName();
using (var inputFile = new FileStream(sourceFile.FullName, FileMode.Open,
FileAccess.Read, FileShare.ReadWrite))
using (var outputFile = new FileStream(copyTartget, FileMode.Create))
inputFile.CopyTo(outputFile, 0x10000);
return copyTartget;
}
}
The following code gives me a System.IO.IOException with the message 'The process cannot access the file'.
private void UnPackLegacyStats()
{
DirectoryInfo oDirectory;
XmlDocument oStatsXml;
//Get the directory
oDirectory = new DirectoryInfo(msLegacyStatZipsPath);
//Check if the directory exists
if (oDirectory.Exists)
{
//Loop files
foreach (FileInfo oFile in oDirectory.GetFiles())
{
//Check if file is a zip file
if (C1ZipFile.IsZipFile(oFile.FullName))
{
//Open the zip file
using (C1ZipFile oZipFile = new C1ZipFile(oFile.FullName, false))
{
//Check if the zip contains the stats
if (oZipFile.Entries.Contains("Stats.xml"))
{
//Get the stats as a stream
using (Stream oStatsStream = oZipFile.Entries["Stats.xml"].OpenReader())
{
//Load the stats as xml
oStatsXml = new XmlDocument();
oStatsXml.Load(oStatsStream);
//Close the stream
oStatsStream.Close();
}
//Loop hit elements
foreach (XmlElement oHitElement in oStatsXml.SelectNodes("/*/hits"))
{
//Do stuff
}
}
//Close the file
oZipFile.Close();
}
}
//Delete the file
oFile.Delete();
}
}
}
I am struggling to see where the file could still be locked. All objects that could be holding onto a handle to the file are in using blocks and are explicitly closed.
Is it something to do with using FileInfo objects rather than the strings returned by the static GetFiles method?
Any ideas?
I do not see problems in your code, everything look ok. To check is the problem lies in C1ZipFile I suggest you initialize zip from stream, instead of initialization from file, so you close stream explicitly:
//Open the zip file
using (Stream ZipStream = oFile.OpenRead())
using (C1ZipFile oZipFile = new C1ZipFile(ZipStream, false))
{
// ...
Several other suggestions:
You do not need to call Close() method, with using (...), remove them.
Move xml processing (Loop hit elements) outsize zip processing, i.e. after zip file closeing, so you keep file opened as least as possible.
I assume you're getting the error on the oFile.Delete call. I was able to reproduce this error. Interestingly, the error only occurs when the file is not a zip file. Is this the behavior you are seeing?
It appears that the C1ZipFile.IsZipFile call is not releasing the file when it's not a zip file. I was able to avoid this problem by using a FileStream instead of passing the file path as a string (the IsZipFile function accepts either).
So the following modification to your code seems to work:
if (oDirectory.Exists)
{
//Loop files
foreach (FileInfo oFile in oDirectory.GetFiles())
{
using (FileStream oStream = new FileStream(oFile.FullName, FileMode.Open))
{
//Check if file is a zip file
if (C1ZipFile.IsZipFile(oStream))
{
// ...
}
}
//Delete the file
oFile.Delete();
}
}
In response to the original question in the subject: I don't know if it's possible to know if a file can be deleted without attempting to delete it. You could always write a function that attempts to delete the file and catches the error if it can't and then returns a boolean indicating whether the delete was successful.
I'm just guessing: are you sure that oZipFile.Close() is enough? Perhaps you have to call oZipFile.Dispose() or oZipFile.Finalize() to be sure it has actually released the resources.
More then Likely it's not being disposed, anytime you access something outside of managed code(streams, files, etc.) you MUST dispose of them. I learned the hard way with Asp.NET and Image files, it will fill up your memory, crash your server, etc.
In the interest of completeness I am posing my working code as the changes came from more than one source.
private void UnPackLegacyStats()
{
DirectoryInfo oDirectory;
XmlDocument oStatsXml;
//Get the directory
oDirectory = new DirectoryInfo(msLegacyStatZipsPath);
//Check if the directory exists
if (oDirectory.Exists)
{
//Loop files
foreach (FileInfo oFile in oDirectory.GetFiles())
{
//Set empty xml
oStatsXml = null;
//Load file into a stream
using (Stream oFileStream = oFile.OpenRead())
{
//Check if file is a zip file
if (C1ZipFile.IsZipFile(oFileStream))
{
//Open the zip file
using (C1ZipFile oZipFile = new C1ZipFile(oFileStream, false))
{
//Check if the zip contains the stats
if (oZipFile.Entries.Contains("Stats.xml"))
{
//Get the stats as a stream
using (Stream oStatsStream = oZipFile.Entries["Stats.xml"].OpenReader())
{
//Load the stats as xml
oStatsXml = new XmlDocument();
oStatsXml.Load(oStatsStream);
}
}
}
}
}
//Check if we have stats
if (oStatsXml != null)
{
//Process XML here
}
//Delete the file
oFile.Delete();
}
}
}
The main lesson I learned from this is to manage file access in one place in the calling code rather than letting other components manage their own file access. This is most apropriate when you want to use the file again after the other component has finished it's task.
Although this takes a little more code you can clearly see where the stream is disposed (at the end of the using), compared to having to trust that a component has correctly disposed of the stream.