I made a program for splitting a cell into two cells and write them in a different sheets but after I run it the excel file gets corrupted.
IWorkbook workbook;
using(FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read))
{
workbook = new XSSFWorkbook(stream);
}
IWorkbook newWorkbook = new XSSFWorkbook();
ISheet sheet = workbook.GetSheetAt(0);
ISheet oneWordSheet = newWorkbook.CreateSheet();
ISheet moreWordsSheet = newWorkbook.CreateSheet();
IRow tmpRow;
for(int i = 5; i < 100/*sheet.LastRowNum*/ + 1; i++)
{
tmpRow = sheet.GetRow(i);
string[] strings = tmpRow.GetCell(2).StringCellValue.Split(' ');
string companyName = strings[0];
bool parseFailed = true;
for(int j = 1; parseFailed && j < strings.Length; j++)
{
try
{
int.Parse(strings[j]);
parseFailed = false;
}
catch (FormatException)
{
companyName += strings[j];
j++;
}
}
tmpRow.CreateCell(4).SetCellValue(companyName);
if(companyName.Trim().Split(' ').Length < 2)
{
copyRowToSheet(tmpRow, oneWordSheet);
}
else
{
copyRowToSheet(tmpRow, moreWordsSheet);
}
}
using (FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Write))
{
newWorkbook.Write(stream);
}
I made a copyRowToSheet method like this. It should be correct
private static void copyRowToSheet(IRow row, ISheet sheet)
{
IRow newRow = sheet.CreateRow(sheet.LastRowNum + 1);
newRow.CreateCell(0).SetCellValue(row.GetCell(0).NumericCellValue);
newRow.CreateCell(1).SetCellValue(row.GetCell(1).StringCellValue);
newRow.CreateCell(2).SetCellValue(row.GetCell(4).StringCellValue);
newRow.CreateCell(3).SetCellValue(row.GetCell(2).StringCellValue);
newRow.CreateCell(4).SetCellValue(row.GetCell(3).StringCellValue);
}
I tried writing from workbook instead of newWorkbook, but it still corrupts the file, I also tried removing copyRowToSheet method (just leaving both the if and else case empty but the result doesn't change...
Edit:
I tried removing the whole body of the program leaving just this:
IWorkbook workbook;
using(FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read))
{
workbook = new XSSFWorkbook(stream);
stream.Close();
}
IWorkbook newWorkbook = new XSSFWorkbook();
using (FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Write))
{
workbook.Write(stream);
stream.Close();
}
If I'm not wrong this should only read the file and then save it back without editing anything, but it still corrupts the file
I hit the same issue myself a couple of weeks ago when i was starting out with npoi. Quite a tricky one to diagnose as the code you are using is repeated time and again in tutorials and blogs.
The problem occurs when you are creating your second FileStream to write back the spreadsheet to disk. You are writing to the same file that you read earlier.
The behavour of FileMode.Open when writing to an existing file is to append the data to the end of the file. This results in you having 2 excel spreadsheets in a single file which when you open it is declared corrupt.
FileMode.Create on the other hand will overwrite an existing file so this is more likely to be what you need.
using (FileStream stream = new FileStream(path, FileMode.Create, FileAccess.Write))
{
workbook.Write(stream);
stream.Close();
}
Here's the docs file FileMode as there are alternates to Create that you may prefer.
Doc for FileMode
Related
I use NPOI 2.6.0-rc-3 with .net framework 4.8.1 for updating .xlsx file. Excel file includes charts with it. excel file get crashed and after saving. After recovering the same file it losses charts in excel.
Used the following code.
XSSFWorkbook wb1 = null;
using (var file = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite))
{
wb1 = new XSSFWorkbook(file);
file.Close();
//Updated the cell values here
using (var file2 = new FileStream(filePath, FileMode.Create, FileAccess.ReadWrite))
{
wb1.Write(file2);
file2.Close();
}
}
Please help regrading this matter
Try to modify the cells out of the using block (you dont need to keep the file open to modify the IWorkbook) and then save it using a diferent stream:
IWorkbook wb1 = null;
using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
wb1 = new XSSFWorkbook(file);
}
//Updated the cell values here
using (FileStream fileWrite = new FileStream(filePath, FileMode.Create, FileAccess.Write))
{
wb1.Write(fileWrite);
}
I am creating a new excel file using a template file, but I am unable to edit the contents in the new file created, please assist with the same.
Thanks in advance.
FileStream fileStream = new FileStream(filepath, FileMode.Open, FileAccess.Read);
using (ExcelPackage package = new ExcelPackage(fileStream))
{
package.Save();
}
string name = "filecreated.xlsx";
string fileType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
fileStream.Position = 0;
//return file
return File(fileStream, fileType, name);```
It Seems like you are opening the file in read only access mode
FileStream fileStream = new FileStream(filepath, FileMode.Open,
FileAccess.Read);
Will you please try like
FileInfo existingFile = new FileInfo(filepath);
using (ExcelPackage package = new ExcelPackage(existingFile))
{
//As we have not modified the file, its useless to call Save()
//This will override the opened file
package.Save();
}
I am reading and writing to the same PDF at the same time i am getting error "The document has no catalog object (meaning: it's an invalid PDF)" on this line "PdfReader pdfReader = new PdfReader(inputPdf2);" in the below code snippet.
iTextSharp.text.pdf.PdfCopy pdfCopy = null;
Document finalPDF = new Document();
//pdfReader = null;
FileStream fileStream = null;
int pageCount = 1;
int TotalPages = 20;
try
{
fileStream = new FileStream(finalPDFFile, FileMode.OpenOrCreate, FileAccess.Write);
pdfCopy = new PdfCopy(finalPDF, fileStream);
finalPDF.Open();
foreach (string inputPdf1 in inputPDFFiles)
{
if (File.Exists(inputPdf1))
{
var bytes = File.ReadAllBytes(inputPdf1);
PdfReader pdfReader = new PdfReader(bytes);
fileStream = new FileStream(inputPdf1, FileMode.Open, FileAccess.Write);
var stamper = new PdfStamper(pdfReader, fileStream);
var acroFields = stamper.AcroFields;
stamper.AcroFields.SetField(acrofiled.Key, "Page " + 1+ " of " + 16);
stamper.FormFlattening = true;
stamper.Close();
stamper.Dispose();
fileStream.Close();
fileStream.Dispose();
pdfReader.Close();
pdfReader.Dispose();
}
}
foreach (string inputPdf2 in inputPDFFiles)
{
if (File.Exists(inputPdf2))
{
PdfReader pdfReader = new PdfReader(inputPdf2);
int pageNumbers = pdfReader.NumberOfPages;
for (int pages = 1; pages <= pageNumbers; pages++)
{
PdfImportedPage page = pdfCopy.GetImportedPage(pdfReader, pages);
PdfCopy.PageStamp pageStamp = pdfCopy.CreatePageStamp(page);
pdfCopy.AddPage(page);
}
pdfReader.Close();
pdfReader.Dispose();
}
}
pdfCopy.Close();
pdfCopy.Dispose();
finalPDF.Close();
finalPDF.Dispose();
fileStream.Close();
fileStream.Dispose();
please help me in order to fix issue or give me any alternate approach
In your first loop you overwrite each of your files with a manipulated version like this:
var bytes = File.ReadAllBytes(inputPdf1);
PdfReader pdfReader = new PdfReader(bytes);
fileStream = new FileStream(inputPdf1, FileMode.Open, FileAccess.Write);
var stamper = new PdfStamper(pdfReader, fileStream);
[...]
Using FileMode.Open here is an error. You want to replace the existing file with a new one, and for such a use case you have to use FileMode.Create or FileMode.Truncate.
Using FileMode.Open results in the original file content remaining there and you writing into it. Thus, if your new file content is shorter than the original one (which can happen when flattening a form), your new file keeps a tail segment of the original file. In PDFs there are relevant lookup information at the end, so upon reading this new file the PdfReader finds the lookup information of the old file which don't match the new content anymore at all.
By the way, you create the PdfCopy like this:
fileStream = new FileStream(finalPDFFile, FileMode.OpenOrCreate, FileAccess.Write);
pdfCopy = new PdfCopy(finalPDF, fileStream);
This is wrong for the same reason: If there already is PDF there, FileMode.OpenOrCreate works just like FileMode.Open with the unwanted effects described above.
Thus, you should replace the FileMode values for streams you write to with FileMode.Create.
I'm using a FileStream to lock the File to be not writeable for other processes and also read and write to it, I'm using following method for it:
public static void ChangeOrAddLine(string newLine, string oldLine = "")
{
string filePath = "C:\\test.txt";
FileMode fm = FileMode.Create;
//FileMode fm = FileMode.OpenOrCreate;
using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read))
using (StreamReader sr = new StreamReader(fs))
using (StreamWriter sw = new StreamWriter(fs))
{
List<string> lines = sr.ReadToEnd().Split(new string[] { "\r\n" }, StringSplitOptions.None).ToList();
bool lineFound = false;
if (oldLine != "")
for (int i = 0; i < lines.Count; i++)
if (lines[i] == oldLine)
{
lines[i] = newLine;
lineFound = true;
break;
}
if (!lineFound)
lines.Add(newLine);
sw.Write(string.Join("\r\n", lines));
}
}
I want to overwrite it with the new content but i don't find the right FileMode, using FileMode.OpenOrCreate just appends the new content to the old and FileMode.Create deletes the file-content at the time, the FileStream fm has been initialized, so the file is empty.
I need to just clear the old content at the moment, when i write the new content to it without losing the write-lock on it during the method is running.
OpenOrCreate just appends ...
Because you don't reposition after the reading.
That also shows the main problem with your approach: The FileStream only has one Position, and the Reader and the Writer heavily use caching.
However, as long as you want to replace everything and really need that locking scheme:
using (FileStream fs = new FileStream(filePath,
FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read))
{
using (StreamReader sr = new StreamReader(fs))
{
... // all the reading
}
fs.Position = 0;
using (StreamWriter sw = new StreamWriter(fs))
{
sw.Write(string.Join("\r\n", lines));
}
fs.SetLength(fs.Position); // untested, something along this line
}
and maybe you have to convince the sw and sr to leave their stream open.
But I have to note that the FileShare.Read flag doesn't make too much sense in this scenario. A reader could see al sorts of inconsistent data, including torn lines and broken UTF8 characters.
I have a windows service writes its log in a text file in a simple format.
Now, I'm going to create a small application to read the service's log and shows both the existing log and the added one as live view.
The problem is that the service locks the text file for adding the new lines and at the same time the viewer application locks the file for reading.
The Service Code:
void WriteInLog(string logFilePath, data)
{
File.AppendAllText(logFilePath,
string.Format("{0} : {1}\r\n", DateTime.Now, data));
}
The viewer Code:
int index = 0;
private void Form1_Load(object sender, EventArgs e)
{
try
{
using (StreamReader sr = new StreamReader(logFilePath))
{
while (sr.Peek() >= 0) // reading the old data
{
AddLineToGrid(sr.ReadLine());
index++;
}
sr.Close();
}
timer1.Start();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void timer1_Tick(object sender, EventArgs e)
{
using (StreamReader sr = new StreamReader(logFilePath))
{
// skipping the old data, it has read in the Form1_Load event handler
for (int i = 0; i < index ; i++)
sr.ReadLine();
while (sr.Peek() >= 0) // reading the live data if exists
{
string str = sr.ReadLine();
if (str != null)
{
AddLineToGrid(str);
index++;
}
}
sr.Close();
}
}
Is there any problem in my code in reading and writing way?
How to solve the problem?
You need to make sure that both the service and the reader open the log file non-exclusively. Try this:
For the service - the writer in your example - use a FileStream instance created as follows:
var outStream = new FileStream(logfileName, FileMode.Open,
FileAccess.Write, FileShare.ReadWrite);
For the reader use the same but change the file access:
var inStream = new FileStream(logfileName, FileMode.Open,
FileAccess.Read, FileShare.ReadWrite);
Also, since FileStream implements IDisposable make sure that in both cases you consider using a using statement, for example for the writer:
using(var outStream = ...)
{
// using outStream here
...
}
Good luck!
Explicit set up the sharing mode while reading the text file.
using (FileStream fs = new FileStream(logFilePath,
FileMode.Open,
FileAccess.Read,
FileShare.ReadWrite))
{
using (StreamReader sr = new StreamReader(fs))
{
while (sr.Peek() >= 0) // reading the old data
{
AddLineToGrid(sr.ReadLine());
index++;
}
}
}
new StreamReader(File.Open(logFilePath,
FileMode.Open,
FileAccess.Read,
FileShare.ReadWrite))
-> this doesn't lock the file.
The problem is when you are writing to the log you are exclusively locking the file down so your StreamReader won't be allowed to open it at all.
You need to try open the file in readonly mode.
using (FileStream fs = new FileStream("myLogFile.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
using (StreamReader sr = new StreamReader(fs))
{
while (!fs.EndOfStream)
{
string line = fs.ReadLine();
// Your code here
}
}
}
I remember doing the same thing a couple of years ago. After some google queries i found this:
FileStream fs = new FileStream(#”c:\test.txt”,
FileMode.Open,
FileAccess.Read,
FileShare.ReadWrite);
i.e. use the FileShare.ReadWrite attribute on FileStream().
(found on Balaji Ramesh's blog)
Have you tried copying the file, then reading it?
Just update the copy whenever big changes are made.
This method will help you to fastest read a text file and without locking it.
private string ReadFileAndFetchStringInSingleLine(string file)
{
StringBuilder sb;
try
{
sb = new StringBuilder();
using (FileStream fs = File.Open(file, FileMode.Open))
{
using (BufferedStream bs = new BufferedStream(fs))
{
using (StreamReader sr = new StreamReader(bs))
{
string str;
while ((str = sr.ReadLine()) != null)
{
sb.Append(str);
}
}
}
}
return sb.ToString();
}
catch (Exception ex)
{
return "";
}
}
Hope this method will help you.