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Problems with returning zip file

I am writing an ASP.NET Core Web API with .NET 5.0 as an exercise.
In MyController.cs there is the method DownloadZip(). Here, it should be possible for the client to download a zip file. By the way, I create a zip file because I did not achieve to transfer multiple pictures. That is the actual goal. Provisionally, the zip file is still stored in the picture folder. Of course, that should not happen either. I simply still have difficulties with web services and transferring zip files via them.
Anyway, in the line return File(fullName, "text/plain"); I get the following error message:
System.InvalidOperationException: No file provider has been configured to process the supplied file.
I found several threads on StackOverflow last Friday about how to transfer a zip file using a memory stream. When I do it this way, the browser shows the individual bytes, but no finished file has been downloaded.
Postings is a list(of post) with
using System;
using System.Collections.Generic;
namespace ImageRepository
{
public sealed class Posting
{
public DateTime CreationTime { get; set; }
public List<ImageProperties> Imageproperties { get; }
public Posting(DateTime creationTime, List<ImageProperties> imPr)
{
CreationTime = creationTime;
Imageproperties = imPr;
}
}
}
And Imageproperties is the following:
namespace ImageRepository
{
public sealed class ImageProperties
{
public string FullName { get; set; }
public string _Name { get; set; }
public byte[] DataBytes { get; set; }
public ImageProperties(string FullName, string Name, byte[] dataBytes)
{
this.FullName = FullName;
this._Name = Name;
this.DataBytes = dataBytes;
}
}
}
MyController.cs
using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using ImageRepository;
using System.IO.Compression;
namespace WebApp2.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class MyController : ControllerBase
{
private readonly IImageTransferRepository imageRepository;
private readonly System.Globalization.CultureInfo Deu = new System.Globalization.CultureInfo("de-DE");
public MyController(IImageTransferRepository imageTransferRepository)
{
this.imageRepository = imageTransferRepository;
}
//––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
[HttpGet("WhatAreTheNamesOfTheLatestPictures")] // Route will be https://localhost:44355/api/My/WhatAreTheNamesOfTheLatestPictures/
public ActionResult GetNamesOfNewestPosting()
{
List<string> imageNames = this.imageRepository.GetImageNames();
if (imageNames.Count == 0)
{
return NoContent();
}
return Ok(imageNames);
}
//––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
[HttpGet("ImagesOfLatestPost")] //route will be https://localhost:44355/api/My/ImagesOfLatestPost
public ActionResult DownloadZip()
{
List<Posting> Postings = this.imageRepository.GetImages();
if (Postings is null || Postings.Count == 0)
{
return NoContent();
}
System.DateTime now = System.DateTime.Now;
string now_as_string = now.ToString("G", Deu).Replace(':', '-');
string folderPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyPictures);
string fullName = $"{folderPath}\\{now_as_string}.zip";
using (ZipArchive newFile = ZipFile.Open(fullName, ZipArchiveMode.Create))
{
for (int i = 0; i < Postings[0].Imageproperties.Count; i++)
{
newFile.CreateEntryFromFile(Postings[0].Imageproperties[i].FullName,
Postings[0].Imageproperties[i]._Name);
}
}
return File(fullName, "text/plain");
}
}
}
Edit June 20, 2022, 4:16 pm
Based on Bagus Tesa's comment, I wrote the following:
byte[] zip_as_ByteArray = System.IO.File.ReadAllBytes(fullName);
return File(zip_as_ByteArray, "application/zip");
The automatic download takes place, but I still have to rename the file by attaching (a) .zip so that Windows recognises it as a zip file.
Furthermore, there is still the problem that I am still creating the zip file on the hard disk (using (ZipArchive newFile = ZipFile.Open(fullName, ZipArchiveMode.Create))). How can I change this?

Thanks to the thread linked by Bagus Tesa, I can now answer my question. I have adapted a few things to my needs, see for-loop, because I have several images.
[HttpGet("ImagesOfLatestPost")] //route will be https://localhost:44355/api/My/ImagesOfLatestPost
public ActionResult DownloadZip()
{
List<Posting> Postings = this.imageRepository.GetImages();
if (Postings is null || Postings.Count == 0)
{
return NoContent();
}
byte[] compressedBytes;
using (var outStream = new System.IO.MemoryStream())
{
using (var archive = new ZipArchive(outStream, ZipArchiveMode.Create, true))
{
for (int i = 0; i < Postings[0].Imageproperties.Count; i++)
{
ZipArchiveEntry fileInArchive = archive.CreateEntry(Postings[0].Imageproperties[i]._Name, CompressionLevel.Optimal);
using System.IO.Stream entryStream = fileInArchive.Open();
using System.IO.MemoryStream fileToCompressStream = new System.IO.MemoryStream(Postings[0].Imageproperties[i].DataBytes);
fileToCompressStream.CopyTo(entryStream);
}
}
compressedBytes = outStream.ToArray();
}
return File(compressedBytes, "application/zip", $"Export_{System.DateTime.Now:yyyyMMddhhmmss}.zip");
}

Read CSV from variable using CsvHelper (or similar library)

I've got a function that makes something equivalent to a web request, and it returns a formatted CSV. My goal is to now import this data into CsvHelper. However, I can't seem to get CSVParser to read from static text, only from a stream.
I could write the output to a file then read it back, but I feel that doesn't make much sense here.
I'm not tied down at all to CsvHelper, however I can't seem to find a CSV library that supports this behavior. How should I do this?
var csvString = functionThatReturnsCsv()
/* as string:
columnA,columnB
dataA,dataB
*/
// my goal
???.parse(csvString)

You can convert the string to a Stream in-memory and then use that as the source for your CSV reader:
public static Stream StringAsStream(string value)
{
return StringAsStream(value, System.Text.Encoding.UTF8);
}
public static Stream StringAsStream(string value, System.Text.Encoding encoding)
{
var bytes = encoding.GetBytes(value);
return new MemoryStream(bytes);
}
Usage:
using (var stream = StringAsStream("hello"))
{
// csv reading code here
}
or
using (var stream = StringAsStream("hello", Encoding.Ascii))
{
// csv reading code here
}
Try it online
Note If you are reading from a source that can return a Stream (like a web request), you should use that Stream rather than doing this.

You could use StringReader. The CsvReader constructor takes a TextReader argument rather than a Stream. If you did have a stream instead of a string, just replace StringReader with StreamReader.
public static void Main(string[] args)
{
using (var reader = new StringReader(FunctionThatReturnsCsv()))
using (var csv = new CsvReader(reader))
{
var results = csv.GetRecords<Foo>().ToList();
}
}
public static string FunctionThatReturnsCsv()
{
return "columnA,columnB\ndataA,dataB";
}
public class Foo
{
public string columnA { get; set; }
public string columnB { get; set; }
}

Writing to a blob stream - how to fail and clean up?

Using Azure storage, I'm writing to a blob using a stream. I have a method something like this:
public async Task<BlobSteamContainer> GetBlobStreamAsync(string filename, string contentType = "text/csv")
{
var blob = container.GetBlockBlobReference($"{filename}--{Guid.NewGuid().ToString()}.csv");
blob.Properties.ContentType = contentType;
return new BlobSteamContainer(blob.Uri.ToString(), await blob.OpenWriteAsync());
}
Where BlobStreamContainer is just a simple object so I can keep track of the filename and the stream together:
public class BlobSteamContainer : IDisposable
{
public CloudBlobStream Stream { get; private set; }
public string Filename { get; private set; }
public BlobSteamContainer(string filename, CloudBlobStream stream)
{
Stream = stream;
Filename = filename;
}
public void Dispose()
{
Stream.Close();
Stream?.Dispose();
}
}
And then I use it something like this:
using (var blobStream = await GetBlobStreamAsync(filename))
using (var outputStream = new StreamWriter(blobStream.Stream))
using (var someInputStream = ...)
{
try
{
outputStream.WriteLine("write some stuff...");
//....processing
if (someCondition) {
throw new MyException("can't write the file");
}
//....more processing
outputStream.Flush();
}
catch(MyException e)
{
// what to do here? I want to stop writing
// and remove any trace of the file in azure
throw; // let the higher ups handle this
}
}
Where somecondition is something that I know before hand (obviously there's more going on involving processing an input stream and writing out as I go). If everything is fine, then this works great. My problem is on figuring out the best way to handle the case where an exception is thrown during writing.
I tried just deleting the file in the catch like this:
DeleteBlob(blobStream.Filename);
where:
public void DeleteBlob(string filename)
{
var blob = container.GetBlobReference(filename);
blob.Delete();
}
But the problem is that the file might not have been created yet and so this will throw a Microsoft.WindowsAzure.Storage.StorageException telling me the file wasn't found (and then the file will end up getting created anyway!).
So what would be the cleanest way to handle this?

How to check if IIS closed the connection after sending file

I have a web application where I'm using OWIN to send files to the client by implementing Microsoft.Owin.FileSystems.IFileInfo
using System;
using System.IO;
using Microsoft.Owin.FileSystems;
public class CmsFileInfo : IFileInfo
{
private readonly FileInfo _fileInfo;
private readonly string _physicalPath;
public CmsFileInfo(FileInfo fileInfo)
{
_fileInfo = fileInfo;
_physicalPath = fileInfo.FullName;
Name = fileInfo.Name;
LastModified = fileInfo.LastWriteTimeUtc;
}
public Stream CreateReadStream()
{
return new FileStream(
_physicalPath,
FileMode.Open,
FileAccess.Read,
FileShare.Read,
1024 * 64,
FileOptions.SequentialScan);
}
public long Length
{
get { return _fileInfo.Length; }
}
public string PhysicalPath { get { return null; } }
public string Name { get; private set; }
public DateTime LastModified { get; private set; }
public bool IsDirectory { get { return false; } }
}
For me, it seems that is is working fine. But then we had some problems with iTunes. An apple supporter gave me the following answer:
It seems when we request your image, your server isn't closing the connection. Consider hosting your image on a different and seeing if that resolves the issue.
We moved the podcast image to azure and I'm now sending a 302 redirect. This solved our problem with iTunes.
But: How can I close the connection? How can I test if the server closed the connection? What's wrong with my IFileInfo implementation?

You can use Wireshark to inspect whether or not the underlying TCP connection was closed.

WordPress XML RPC Upload Image C#

Hey all, I am developing a site for work that will push info from a database into Wordpress using Wordpress XML RPC. I can grab info and post it just fine, however when I get to the point of uploading images it seems to work(no runtime errors/image in WP Media Tab) however it uploads a broken image link. It appears it is somehow no getting the data from my image and I am not certain why here is some of my code.
MemoryStream ms = new MemoryStream();
System.Drawing.Image img = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath("_Images/DownloadButton-PSD.png"));
img.Save(ms, ImageFormat.Png);
byte[] imagebytes = new byte[ms.Length];
ms.Position = 0;
ms.Read(imagebytes, 0, Convert.ToInt32(ms.Length));
after that code loads the image info I pass it to the function in the format of a Data variable
var data = new Data
{
Base64 = Convert.ToBase64String(imagebytes),
Name = "DownloadButton-PSD.png",
Type = "image/png",
Overwrite = false,
};
_wpWrapper.UploadFile(data);
FYI: I am also using the dll's from
http://joeblogs.codeplex.com/
for my project
The Data Class looks like this:
public class Data
{
public string Name { get; set; }
public string Type { get; set; }
public string Base64 { get; set; }
public bool Overwrite { get; set; }
}
The Upload File Function looks like this:
public void UploadFile(Data data)
{
var xmlRpcData = Map.From.Data(data);
var result = _wrapper.UploadFile(this.BlogID, Username, Password, xmlRpcData);
}

In JoeBlogs library try using the class MetaWeblogWrapper and method: MediaObjectInfo NewMediaObject(MediaObject mediaObject) - for upload image.