Develop Reference

C# Streamwriter - Problem with the encoding

I have some product data that I want to write into a csv file. First I have a function that writes the header into the csv file:
using(StreamWriter streamWriter = new StreamWriter(path))
{
string[] headerContent = {"banana","apple","orange"};
string header = string.Join(",", headerContent);
streamWriter.WriteLine(header);
}
Another function goes over the products and writes their data into the csv file:
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Open), Encoding.UTF8))
{
foreach (var product in products)
{
await streamWriter.WriteLineAsync(product.ToString());
}
}
When writing the products into the csv file and do it with FileMode.Open and Encoding.UTF8, the encoding is set correctly into the file meaning that special characters in german or french get shown correctly. But the problem here is that I overwrite my header when I do it like this.
The solution I tried was to not use FileMode.Open but to use FileMode.Append which works, but then for some reason the encoding just gets ignored.
What could I do to append the data while maintaing the encoding? And also why is this happening in the first place?
EDIT:
Example with FileMode.Open:
Fußpflegecreme
Example with FileMode.Append:
Fußpflegecreme

The important question here is: what does the file actually contain; for example, if I use the following:
using System.Text;
string path = "my.txt";
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Create), Encoding.UTF8))
{
streamWriter.WriteLine("Fußpflegecreme 1");
}
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Append), Encoding.UTF8))
{
streamWriter.WriteLine("Fußpflegecreme 2");
}
// this next line is lazy and inefficient; only good for quick tests
Console.WriteLine(BitConverter.ToString(File.ReadAllBytes(path)));
then the output is (re-formatted a little):
EF-BB-BF-
46-75-C3-9F-70-66-6C-65-67-65-63-72-65-6D-65-20-31-0D-0A-
46-75-C3-9F-70-66-6C-65-67-65-63-72-65-6D-65-20-32-0D-0A
The first line (note: there aren't any "lines" in the original hex) is the UTF-8 BOM; the second and third lines are the correctly UTF-8 encoded payloads. It would help if you could show the exact bytes that get written in your case. I wonder if the real problem here is that in your version, there is no BOM, but the rest of the data is correct. Some tools, in the absence of a BOM, will choose the wrong encoding. But also, some tools: in the presence of a BOM: will incorrectly show some garbage at the start of the file (and may also, because they're clearly not using the BOM: use the wrong encoding). The preferred option is: specify the encoding explicitly when reading the file, and use a tool that can handle the presence of absence of a BOM.
Whether or not to include a BOM (especially in the case of UTF-8) is a complex question, and there are pros/cons of each - and there are tools that will work better, or worse, with each. A lot of UTF-8 text files do not include a BOM, but: there is no universal answer. The actual content is still correctly UTF-8 encoded whether or not there is a BOM - but how that is interpreted (in either case) is up to the specific tool that you're using to read the data (and how that tool is configured).

I think this will be solved once you explicitly choose the utf8 encoding when writing the header. This will prefix the file with a BOM.

XML file keeps being overwritten

So I'm currently working on an ASP.NET project. It requires me to write a List<> onto a XML file. I created a "data.xml" file within the project folder and here are my few lines of code:
XmlSerializer serializer = new XmlSerializer(typeof(List<BookItem>));
TextWriter filestream = new StreamWriter("data.xml");
serializer.Serialize(filestream, book);
filestream.Close();
it works well
like this
until I want to add a new record, then the file is overwritten every single time. I believe i only need few tricky lines of code to solve this problem but since my research didn't bring up any answer, i really need your help.

Adobe Reader could not open 'StreamTest5.pdf' because it is either not a supported file or file has been damaged error

I am trying to create a pdf file using file stream and while the file is being created in the specified folder of the path, when I try to open the file Adobe Reader is throwing the error that I mentioned above in the title. I am not sure what I am doing wrong but I would greatly appreciate it if someone could look into it and help me out. Thank you!. Here is my code for the filestream:
System.IO.FileStream wFile;
byte[] byteData = null;
byteData = Encoding.ASCII.GetBytes("FileStream Test");
string filePath = $"{_ApplicationPath}PrintedResults\\StreamTest5.pdf";
wFile = new FileStream(filePath, FileMode.Create);
wFile.Write(byteData, 0, byteData.Length);
wFile.Close();
using (var fileStream = new FileStream(filePath, FileMode.Open))
{
Console.WriteLine("This is a test stream file");
}
System.Diagnostics.Process.Start(filePath);

You are writing a text file with the contents "FileStream Test" but naming it with a file extension of ".PDF". This is not a PDF file. It is a text file with a misleading name. Adobe Reader is correctly reporting that it is not a valid PDF.

This is not an answer but I don't have enough reputation to add it as a comment:
You might want to look to 3rd party library offered by http://www.dynamicpdf.com/
Their free evaluation version is quite capable and it is not time limited as they say on their website. With a little more effort you can create quite complicated PDFs with only the evaluation version!

Create ZipArchive from XML with base64 encoded content

I am creating an XML file on the fly.
One of it's nodes contains a ZIP file encoded as a BASE64 string.
I then create another ZIP file.
I add this XML file and a few other JPEG files.
I output the file to the browser.
I am unable to open the FINAL ZIP file.
I get: "Windows cannot open the folder. The Compressed(zipped) Folder'c:\path\file.zip' is invalid."
I am able to save my original XML file to the file system.
I can open that XML file, decode the ZIP node and save to the file system.
I am then able to open that Zip file with no problems.
I can create the final ZIP file, OMIT my XML file, and the ZIP file opens no problem.
I seem to only have an issue with I attempt to ZIP an XML file that has a node with ZIP content encoded as a BASE64 string.
Any ideas? Code snipets are below. Heavily edited.
XDocument xDoc = new XDocument();
XDocument xDocReport = new XDocument();
XElement xNodeReport;
using (FileStream fsData = new FileStream(strFullFilePath, FileMode.Open, FileAccess.Read)) {
xDoc = XDocument.Load(fsData);
xNodeReport = xDoc.Element("Data").Element("Reports").Element("Report");
//SNIP
//create XDocument xDocReport
//SNIO
using (MemoryStream zipInMemoryReport = new MemoryStream()) {
using (ZipArchive zipFile = new ZipArchive(zipInMemoryReport, ZipArchiveMode.Update)) {
//Add REPORT to ZIP file
ZipArchiveEntry entryReport = zipFile.CreateEntry("data.xml");
using (StreamWriter writer = new StreamWriter(entryReport.Open())) {
writer.Write(xDocReport.ToString());
} //END USING report entry
}
xNodeReport.Value = System.Convert.ToBase64String(zipInMemoryReport.GetBuffer());
//I am able to write this file to disk and manipulate it no problem.
//File.WriteAllText("c:\\users\\snip\\desktop\\Report.xml",xDoc.ToString());
}
//create ZIP for response
using (MemoryStream zipInMemory = new MemoryStream()) {
using (ZipArchive zipFile = new ZipArchive(zipInMemory, ZipArchiveMode.Update)) {
//Add REPORT to ZIP file
ZipArchiveEntry entryReportWrapper = zipFile.CreateEntry("Report.xml");
//THIS IS THE STEP THAT makes the Zip "invalid". Although i can open and manipulate this source file no problem.
//********
using (StreamWriter writer = new StreamWriter(entryReportWrapper.Open())) {
xDoc.Save(writer);
}
//Add JPEG(s) to report
//Create Charts
if (chkDLSalesPrice.Checked) {chartDownloadSP.SaveImage(entryChartSP.Open(), ChartImageFormat.Jpeg);}
if (chkDLSalesDOM.Checked) {chartDownloadDOM.SaveImage(entryChartDOM.Open(), ChartImageFormat.Jpeg);}
if (chkDLSPLP.Checked) {chartDownloadSPLP.SaveImage(entryChartSPLP.Open(), ChartImageFormat.Jpeg);}
if (chkDLSPLP.Checked) {chartDownloadLP.SaveImage(entryChartLP.Open(), ChartImageFormat.Jpeg);}
} // END USING ziparchive
Response.Clear();
Response.AppendHeader("content-disposition", "attachment; filename=file.zip");
Response.ContentType = "application/zip";
Response.BinaryWrite(zipInMemory.GetBuffer());
Response.End();

Without a good, minimal, complete code example, it's impossible to know for sure what bugs are in the code. But there are at least two apparent errors in the code snippet you posted, one of which could easily be responsible for the "invalid .zip" error:
In the statement writer.Write(xDocReport.ToString());, the variable xDocReport has not been initialized to anything useful, at least not in the code you posted. So you'll get an empty XML document in the archive.
Since the code example is incomplete, it's possible you just omitted from the code example in your question the initialization of that variable to something else. In any case, even if you didn't that would just lead to an empty XML document in the archive, not an invalid archive.
More problematic though…
You are calling GetBuffer() on your MemoryStream objects, instead of ToArray(). You want the latter. The former gets the entire backing buffer for the MemoryStream object, including the uninitialized bytes past the end of the valid stream. Since a valid .zip file includes a CRC value at the end of the file, adding extra data beyond that causes anything trying to read the file as a .zip archive to miss the correct CRC, reading the uninitialized data instead.
Replace your calls to GetBuffer() with calls to ToArray() instead.
If the above does not lead to a solution for your problem, you should edit your post, to provide a better code example.
One last comment: there is no point in initializing a variable like xDoc to an empty XDocument object when you're going to just replace that object with a different one (e.g. by calling XDocument.Load()).

GZipStream not working

I am using the following C# code to compress a file:
// Open the stream we want to compress
FileStream fs = File.Create(#"C:\Projects\Samples\test\compressed.zip", 0);
// Creates the GZipStream
GZipStream gzip = new GZipStream(fs, CompressionMode.Compress);
// Reading the content to compress
byte[] bytes = File.ReadAllBytes(#"C:\Projects\Samples\samplefile.xml");
// Writing compressed content
gzip.Write(bytes, 0, bytes.Length);
gzip.Close(); // This also closes the FileStream (the underlying stream)
However, when I extract the file from windows explorer the file loses it's extension so instead of samplefile.xml it just becomes samplefile. Same thing happened with .txt file not just .xml file.
Can you help me see what I'm doing wrong?

ok found the problem:
Line 2 has to be as follows:
FileStream fs = File.Create(#"C:\Projects\Samples\test\compressed.xml.zip", 0);

GZipStream doesn't create zip archives. It creates a gzip file, which contains only one file, and doesn't necessarily store a filename at all. Normally you should use the .gz extension to identify a gzip file, and it's conventional to use the entire name of the original file with .gz appended on the end. See also here for more information about gzip format: http://en.wikipedia.org/wiki/Gzip#File_format
If you actually want to create zip archives, you might want to use a library like SharpZipLib: http://www.icsharpcode.net/opensource/sharpziplib/