Having some problems with CsvHelper and writing to a memory stream. I've tried flushing the stream writer and setting positions and everything else tried. I figure I've narrowed it down to a really simple test case that obviously fails. What am I doing wrong here?
public OutputFile GetTestFile()
{
using (var ms = new MemoryStream())
using (var sr = new StreamWriter(ms))
using (var csv = new CsvWriter(sr))
{
csv.WriteField("test");
sr.Flush();
return new OutputFile
{
Data = ms.ToArray(),
Length = ms.Length,
DataType = "text/csv",
FileName = "test.csv"
};
}
}
[TestMethod]
public void TestWritingToMemoryStream()
{
var file = GetTestFile();
Assert.IsFalse(file.Data.Length == 0);
}
Editing the correct answer in for people googling as this corrected code actually passes my test. I have no idea why writing to a StringWriter then converting it to bytes solves all the crazy flushing issues, but it works now.
using (var sw = new StringWriter())
using (var csvWriter = new CsvWriter(sw, config))
{
csvWriter.WriteRecords(records);
return Encoding.UTF8.GetBytes(sw.ToString());
}
Since CSVHelper is meant to collect several fields per row/line, it does some buffering itself until you tell it the current record is done:
csv.WriteField("test");
csv.NextRecord();
sr.Flush();
Now, the memstream should have the data in it. However, unless there is more processing elsewhere, the result in your OutputFile is wrong: Data will be byte[] not "text/csv". It seems like StringWriter would produce something more appropriate:
string sBuff;
using (StringWriter sw = new StringWriter())
using (CsvWriter csv = new CsvWriter(sw))
{
csv.WriteRecord<SomeItem>(r);
sBuff = sw.ToString();
}
Console.WriteLine(sBuff);
"New Item ",Falcon,7
Related
Please tell me tell me what I'm doing wrong
using (var mem = new MemoryStream())
{
var writer = new StreamWriter(mem);
writer.Write(csvText);
writer.Flush();
using (var reader = new StreamReader(mem))
{
mem.Seek(0, SeekOrigin.Begin);
using (var csvReader = new CsvReader(reader))
{
while (csvReader.Read())
{
// some unreach code
}
}
}
writer.Dispose();
}
The code inside while is unreached, and I can't understand why. csvText is a not empty string variable.
But the reader can't read it. I understand that most likely I made a stupid mistake, but I will be glad to resolve it. Thanks.
I am unsure what I am doing wrong. The files that I create after grabbing a byte[] (which is emailAttachment.Body) and passing it to the method ExtractZipFile, converting it to MemoryStream and then unzipping it, returning it as a KeyValuePair and then Writing to a file using FileStream.
However when I go to open the new created files there is an error in opening them. They are not able to be opened.
The below are in the same class
using Ionic.Zip;
var extractedFiles = ExtractZipFile(emailAttachment.Body);
foreach (KeyValuePair<string, MemoryStream> extractedFile in extractedFiles)
{
string FileName = extractedFile.Key;
using (FileStream file = new FileStream(CurrentFileSystem +
FileName.FileFullPath(),FileMode.Create, System.IO.FileAccess.Write))
{
byte[] bytes = new byte[extractedFile.Value.Length];
extractedFile.Value.Read(bytes, 0, (int) xtractedFile.Value.Length);
file.Write(bytes,0,bytes.Length);
extractedFile.Value.Close();
}
}
private Dictionary<string, MemoryStream> ExtractZipFile(byte[] messagePart)
{
Dictionary<string, MemoryStream> result = new Dictionary<string,MemoryStream>();
MemoryStream data = new MemoryStream(messagePart);
using (ZipFile zip = ZipFile.Read(data))
{
foreach (ZipEntry ent in zip)
{
MemoryStream memoryStream = new MemoryStream();
ent.Extract(memoryStream);
result.Add(ent.FileName,memoryStream);
}
}
return result;
}
Is there something I am missing? I do not want to save the original zip file just the extracted Files from MemoryStream.
What am I doing wrong?
After writing to your MemoryStream, you're not setting the position back to 0:
MemoryStream memoryStream = new MemoryStream();
ent.Extract(memoryStream);
result.Add(ent.FileName,memoryStream);
Because of this, the stream position will be at the end when you try to read from it, and you'll read nothing. Make sure to rewind it:
memoryStream.Position = 0;
Also, you don't have to handle the copy manually. Just let the CopyTo method take care of it:
extractedFile.Value.CopyTo(file);
I'd suggest that you clean up your use of MemoryStream in your code.
I agree that calling memoryStream.Position = 0; will allow this code to work correctly, but it's an easy thing to miss when reading and writing memory streams.
It's better to write code that avoids the bug.
Try this:
private IEnumerable<(string Path, byte[] Content)> ExtractZipFile(byte[] messagePart)
{
using (var data = new MemoryStream(messagePart))
{
using (var zipFile = ZipFile.Read(data))
{
foreach (var zipEntry in zipFile)
{
using (var memoryStream = new MemoryStream())
{
zipEntry.Extract(memoryStream);
yield return (Path: zipEntry.FileName, Content: memoryStream.ToArray());
}
}
}
}
}
Then your calling code would look something like this:
foreach (var extractedFile in ExtractZipFile(emailAttachment.Body))
{
File.WriteAllBytes(Path.Combine(CurrentFileSystem, extractedFile.Path.FileFullPath()), extractedFile.Content);
}
It's just a lot less code and a much better chance of avoiding bugs. The number one predictor of bugs in code is the number of lines of code you write.
Since I find it all a lot of code for a simple operation, here's my two cents.
using Ionic.Zip;
using (var s = new MemoryStream(emailAttachment.Body))
using (ZipFile zip = ZipFile.Read(s))
{
foreach (ZipEntry ent in zip)
{
string path = Path.Combine(CurrentFileSystem, ent.FileName.FileFullPath())
using (FileStream file = new FileStream(path, FileAccess.Write))
{
ent.Extract(file);
}
}
}
I am trying to create a csv with Headers that are going to be use in Multiple languages. this is the current Code that i am using and works for English but not for Japanese as example.
What is the best way to do that? should i have to specify the Culture Info? i tried that but not good results.
Thanks.
private byte[] WriteCsvToMemory(IEnumerable records)
{
using (var memoryStream = new MemoryStream())
using (var streamWriter = new StreamWriter(memoryStream, Encoding.UTF8))
using (var csvWriter = new CsvWriter(streamWriter))
{
csvWriter.WriteField(GetResourceFileValue("ja-jp", "KEY"));
csvWriter.NextRecord();
csvWriter.Configuration.HasHeaderRecord = false;
csvWriter.WriteRecords(records);
streamWriter.Flush();
return memoryStream.ToArray();
}
}
i made a mistake on my code the solution is simple:
using (var streamWriter = new StreamWriter(memoryStream, **Encoding.UTF8** ))
Nothing wrong with the the library.
I am having a hard time creating a ZipArchive successfully on Asp.net core MVC. I have an excel file generated with data that works and I need to put in an archive. This is what I've done so far
public FileResult ExportGoodsReceiptData()
{
var records = _salesService.GetAllReceipts();
var lineRecords = _salesService.GetAllReceiptLines();
var result = _salesService.ExportGoodsReceiptData(records);
var lineResult = _salesService.ExportGoodsReceiptLineData(lineRecords);
byte[] resultArr = StreamToByteArray(result);
byte[] lineResultArr = StreamToByteArray(lineResult);
using(MemoryStream stream = new MemoryStream())
{
using (var archive = new ZipArchive(stream, ZipArchiveMode.Create, true))
{
var zipArchiveEntry = archive.CreateEntry("GoodsReceipts.csv", CompressionLevel.Fastest);
using (var zipStream = zipArchiveEntry.Open())
using (var resultCom = new MemoryStream(resultArr))
{
resultCom.CopyTo(zipStream);
}
}
return new FileStreamResult(stream, "application/zip") { FileDownloadName = "GoodsReceiptsArchive.zip" };
}
}
When I run it, I get the zipfile, but can't open it. It throws error stating that it may have been damaged. I debugged the code to notice that one of the properties (length property) throws an invalidOperation exception. My approach looks identical to most samples I found online. Don't know how else to solve this. Please help.
Your problem is that you're disposing of your memory stream before you return it. Remove this using:
using(MemoryStream stream = new MemoryStream())
Replace it with:
var stream = new MemoryStream();
Asp.Net MVC will automatically dispose of the stream for you.
I want to use the DataContractJsonSerializer to serialize to file in JsonFormat.
The problem is that the WriteObjectmethod only has 3 options XmlWriter, XmlDictionaryWriter and Stream.
To get what I want I used the following code:
var js = new DataContractJsonSerializer(typeof(T), _knownTypes);
using (var ms = new MemoryStream())
{
js.WriteObject(ms, item);
ms.Position = 0;
using (var sr = new StreamReader(ms))
{
using (var writer = new StreamWriter(path, false))
{
string jsonData = sr.ReadToEnd();
writer.Write(jsonData);
}
}
}
Is this the only way or have I missed something?
Assuming you're just trying to write the text to a file, it's not clear why you're writing it to a MemoryStream first. You can just use:
var js = new DataContractJsonSerializer(typeof(T), _knownTypes);
using (var stream = File.Create(path))
{
js.WriteObject(stream, item);
}
That's rather simpler, and should do what you want...
I am actually quite terrified to claim to know something that Jon Skeet doesn't, but I have used code similar to the following which produces the Json text file and maintains proper indentation:
var js = new DataContractJsonSerializer(typeof(T), _knownTypes);
using (var stream = File.Create(path))
{
using (var writer = JsonReaderWriterFactory.CreateJsonWriter(stream, Encoding.UTF8, true, true, "\t"))
{
js.WriteObject(writer, item);
writer.Flush();
}
}
(as suggested here.)