Develop Reference

File upload in MVC Razor file empty? [duplicate]

I'm encountering a problem sending files stored in a database back to the user in ASP.NET MVC. What I want is a view listing two links, one to view the file and let the mimetype sent to the browser determine how it should be handled, and the other to force a download.
If I choose to view a file called SomeRandomFile.bak and the browser doesn't have an associated program to open files of this type, then I have no problem with it defaulting to the download behavior. However, if I choose to view a file called SomeRandomFile.pdf or SomeRandomFile.jpg I want the file to simply open. But I also want to keep a download link off to the side so that I can force a download prompt regardless of the file type. Does this make sense?
I have tried FileStreamResult and it works for most files, its constructor doesn't accept a filename by default, so unknown files are assigned a file name based on the URL (which does not know the extension to give based on content type). If I force the file name by specifying it, I lose the ability for the browser to open the file directly and I get a download prompt. Has anyone else encountered this?
These are the examples of what I've tried so far.
//Gives me a download prompt.
return File(document.Data, document.ContentType, document.Name);
//Opens if it is a known extension type, downloads otherwise (download has bogus name and missing extension)
return new FileStreamResult(new MemoryStream(document.Data), document.ContentType);
//Gives me a download prompt (lose the ability to open by default if known type)
return new FileStreamResult(new MemoryStream(document.Data), document.ContentType) {FileDownloadName = document.Name};
Any suggestions?
UPDATE:
This questions seems to strike a chord with a lot of people, so I thought I'd post an update. The warning on the accepted answer below that was added by Oskar regarding international characters is completely valid, and I've hit it a few times due to using the ContentDisposition class. I've since updated my implementation to fix this. While the code below is from my most recent incarnation of this problem in an ASP.NET Core (Full Framework) app, it should work with minimal changes in an older MVC application as well since I'm using the System.Net.Http.Headers.ContentDispositionHeaderValue class.
using System.Net.Http.Headers;
public IActionResult Download()
{
Document document = ... //Obtain document from database context
//"attachment" means always prompt the user to download
//"inline" means let the browser try and handle it
var cd = new ContentDispositionHeaderValue("attachment")
{
FileNameStar = document.FileName
};
Response.Headers.Add(HeaderNames.ContentDisposition, cd.ToString());
return File(document.Data, document.ContentType);
}
// an entity class for the document in my database
public class Document
{
public string FileName { get; set; }
public string ContentType { get; set; }
public byte[] Data { get; set; }
//Other properties left out for brevity
}

public ActionResult Download()
{
var document = ...
var cd = new System.Net.Mime.ContentDisposition
{
// for example foo.bak
FileName = document.FileName,
// always prompt the user for downloading, set to true if you want
// the browser to try to show the file inline
Inline = false,
};
Response.AppendHeader("Content-Disposition", cd.ToString());
return File(document.Data, document.ContentType);
}
NOTE: This example code above fails to properly account for international characters in the filename. See RFC6266 for the relevant standardization. I believe recent versions of ASP.Net MVC's File() method and the ContentDispositionHeaderValue class properly accounts for this. - Oskar 2016-02-25

I had trouble with the accepted answer due to no type hinting on the "document" variable: var document = ... So I'm posting what worked for me as an alternative in case anybody else is having trouble.
public ActionResult DownloadFile()
{
string filename = "File.pdf";
string filepath = AppDomain.CurrentDomain.BaseDirectory + "/Path/To/File/" + filename;
byte[] filedata = System.IO.File.ReadAllBytes(filepath);
string contentType = MimeMapping.GetMimeMapping(filepath);
var cd = new System.Net.Mime.ContentDisposition
{
FileName = filename,
Inline = true,
};
Response.AppendHeader("Content-Disposition", cd.ToString());
return File(filedata, contentType);
}

To view file (txt for example):
return File("~/TextFileInRootDir.txt", MediaTypeNames.Text.Plain);
To download file (txt for example):
return File("~/TextFileInRootDir.txt", MediaTypeNames.Text.Plain, "TextFile.txt");
note: to download file we should pass fileDownloadName argument

Darin Dimitrov's answer is correct. Just an addition:
Response.AppendHeader("Content-Disposition", cd.ToString()); may cause the browser to fail rendering the file if your response already contains a "Content-Disposition" header. In that case, you may want to use:
Response.Headers.Add("Content-Disposition", cd.ToString());

I believe this answer is cleaner, (based on
https://stackoverflow.com/a/3007668/550975)
public ActionResult GetAttachment(long id)
{
FileAttachment attachment;
using (var db = new TheContext())
{
attachment = db.FileAttachments.FirstOrDefault(x => x.Id == id);
}
return File(attachment.FileData, "application/force-download", Path.GetFileName(attachment.FileName));
}

Below code worked for me for getting a pdf file from an API service and response it out to the browser - hope it helps;
public async Task<FileResult> PrintPdfStatements(string fileName)
{
var fileContent = await GetFileStreamAsync(fileName);
var fileContentBytes = ((MemoryStream)fileContent).ToArray();
return File(fileContentBytes, System.Net.Mime.MediaTypeNames.Application.Pdf);
}

FileVirtualPath --> Research\Global Office Review.pdf
public virtual ActionResult GetFile()
{
return File(FileVirtualPath, "application/force-download", Path.GetFileName(FileVirtualPath));
}

Action method needs to return FileResult with either a stream, byte[], or virtual path of the file. You will also need to know the content-type of the file being downloaded. Here is a sample (quick/dirty) utility method. Sample video link
How to download files using asp.net core
[Route("api/[controller]")]
public class DownloadController : Controller
{
[HttpGet]
public async Task<IActionResult> Download()
{
var path = #"C:\Vetrivel\winforms.png";
var memory = new MemoryStream();
using (var stream = new FileStream(path, FileMode.Open))
{
await stream.CopyToAsync(memory);
}
memory.Position = 0;
var ext = Path.GetExtension(path).ToLowerInvariant();
return File(memory, GetMimeTypes()[ext], Path.GetFileName(path));
}
private Dictionary<string, string> GetMimeTypes()
{
return new Dictionary<string, string>
{
{".txt", "text/plain"},
{".pdf", "application/pdf"},
{".doc", "application/vnd.ms-word"},
{".docx", "application/vnd.ms-word"},
{".png", "image/png"},
{".jpg", "image/jpeg"},
...
};
}
}

If, like me, you've come to this topic via Razor components as you're learning Blazor, then you'll find you need to think a little more outside of the box to solve this problem. It's a bit of a minefield if (also like me) Blazor is your first forray into the MVC-type world, as the documentation isn't as helpful for such 'menial' tasks.
So, at the time of writing, you cannot achieve this using vanilla Blazor/Razor without embedding an MVC controller to handle the file download part an example of which is as below:
using Microsoft.AspNetCore.Mvc;
using Microsoft.Net.Http.Headers;
[Route("api/[controller]")]
[ApiController]
public class FileHandlingController : ControllerBase
{
[HttpGet]
public FileContentResult Download(int attachmentId)
{
TaskAttachment taskFile = null;
if (attachmentId > 0)
{
// taskFile = <your code to get the file>
// which assumes it's an object with relevant properties as required below
if (taskFile != null)
{
var cd = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment")
{
FileNameStar = taskFile.Filename
};
Response.Headers.Add(HeaderNames.ContentDisposition, cd.ToString());
}
}
return new FileContentResult(taskFile?.FileData, taskFile?.FileContentType);
}
}
Next, make sure your application startup (Startup.cs) is configured to correctly use MVC and has the following line present (add it if not):
services.AddMvc();
.. and then finally modify your component to link to the controller, for example (iterative based example using a custom class):
<tbody>
#foreach (var attachment in yourAttachments)
{
<tr>
<td>#attachment.Filename </td>
<td>#attachment.CreatedUser</td>
<td>#attachment.Created?.ToString("dd MMM yyyy")</td>
<td><ul><li class="oi oi-circle-x delete-attachment"></li></ul></td>
</tr>
}
</tbody>
Hopefully this helps anyone who struggled (like me!) to get an appropriate answer to this seemingly simple question in the realms of Blazor…!

while downloading html in pdf,by using third party tool to convert an html page to pdf. getting error- Conversion error: Could not open url

while downloading html code into pdf in selectpdf software. im getting error saying - "Conversion error: Could not open url".im using selectpdf for converting html code to pdf. what is the base url i have to give .
using SelectPdf;
public partial class HtmlcodePrint : System.Web.UI.Page
{
string TxtHtmlCode;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
TxtHtmlCode = #"<html>
<body>
Hello World from selectpdf.com.
</body>
</html>
";
}
}
protected void Btndownloadpdf_Click(object sender, EventArgs e)
{
// read parameters from the webpage
string htmlString = TxtHtmlCode;
string baseUrl = "http://localhost:51868/HtmlcodePrint.aspx";
string pdf_page_size ="A4";
PdfPageSize pageSize = (PdfPageSize)Enum.Parse(typeof(PdfPageSize),
pdf_page_size, true);
string pdf_orientation = "Portrait";
PdfPageOrientation pdfOrientation =
(PdfPageOrientation)Enum.Parse(typeof(PdfPageOrientation),
pdf_orientation, true);
int webPageWidth = 1024;
try
{
webPageWidth = Convert.ToInt32("1024");
}
catch { }
int webPageHeight = 0;
try
{
webPageHeight = Convert.ToInt32("777");
}
catch { }
// instantiate a html to pdf converter object
HtmlToPdf converter = new HtmlToPdf();
// set converter options
converter.Options.PdfPageSize = pageSize;
converter.Options.PdfPageOrientation = pdfOrientation;
converter.Options.WebPageWidth = webPageWidth;
converter.Options.WebPageHeight = webPageHeight;
// create a new pdf document converting an url
PdfDocument doc = converter.ConvertHtmlString(htmlString, baseUrl);
// save pdf document
doc.Save(Response, false, "Sample.pdf");
// close pdf document
doc.Close();
}
}

I know this is old, but I've been working with SelectPdf for a couple of days, so I'll throw in my 2 cents.
You probably don't need a baseUrl...
You don't have to give any baseUrl at all to the ConvertHtmlString function. You can just pass it the html string you want to convert and that's it.
Unless...
You only need to pass it a baseUrl if the html you're converting has relative paths in the external references (example: if you were referencing a stylesheet and wanted to use a relative path, you could provide the baseUrl to show where you wanted the stylesheet to be relative to). It's just so the converter can create the full absolute paths from the relative paths.
So...
If you don't need that functionality or just don't have external references in your html, then you can just use
converter.ConvertHtmlString(htmlString);
Also...
doc.Save(Response, false, "Sample.pdf");
may not be what you're looking for either. I only say this because the comments look like the same ones on the examples on the site for SelectPDF, so I'm assuming you copied the code from there (which is what I originally did too), in which case I want to let you know you don't have to save your PDF doc with that particular version of Save. It actually has 3 overloads to allow you to save your doc as:
a byte array (default)
a stream
a file
an HTTP response (the one you're using now, as shown in the examples from the site)
So, like I pointed out, you're using the one that saves the PDF as a HTTP response, so if you're wanting to save it as an actual PDF file directly, you'll need to change it to
doc.Save(fileName)
with the fileName variable as the absolute or relative path or file name you want to save the PDF to.
Hope this helps

Get text from PDF stored in LocalFolder using iTextSharp

I am trying to get the text from a PDF stored in localStorage in a Windows Phone 8.1 application,but I always get an FileNotFoundException.
To explain the whole story, I get a PDF from an online source, I store it to a folder with name same as the username (The username is an email address, but I tried also without the # sign) of the user and then I want to get some text from the PDF file. I use iTextSharp and follow the examples, but cannot succeed. When I send the PDF to the Launcher is opening succesfully with another app like Acrobat Reader.
My function is like below. I first send an PDF Object, which has an attribute called Path and it is stored to folder specific to the username of the user.
Then I get the pdf as a StorageFile Item. When I create the PDFReader calling the constructor I get a FileNotFoundException. Does anybody knows or can guess what can be the problem? Is iTextSharp compatible with Windows Phone 8.1?
internal async Task<bool> OpenPdfFromDownloadedCollections(PDF pdfToOpen, string username)
{
try
{
StorageFolder folder = ApplicationData.Current.LocalFolder;
var pdfFolder = await folder.GetFolderAsync(username + "PDFs");
var pdf = await pdfFolder.GetFileAsync(Object.Path);
StringBuilder text = new StringBuilder();
using (PdfReader reader = new PdfReader(pdf.Path))
{
for (int i = 1; i <= reader.NumberOfPages; i++)
{
string thePage = PdfTextExtractor.GetTextFromPage(reader, i, its);
string[] theLines = thePage.Split('\n');
foreach (var theLine in theLines)
{
text.AppendLine(theLine);
}
}
}
return true;
}
catch (Exception)
{
return false;
}
}

var pdf = await pdfFolder.GetFileAsync(Object.Path);
In this line of code you should only pass the file name but you are giving the whole Path as parameter. As pdfFolder currently represents the path.

How to return an image from a controller method?

I want to take the mp3 albumart in the mp3 file, using TagLib. I am using that code, it gives the System.Drawing.Bitmap. How to display in the Webpage. I am Using MVC.
var file12 = TagLib.File.Create(file);
if (file12.Tag.Pictures.Length >= 1)
{
var bin = (byte[])(file12.Tag.Pictures[0].Data.Data);
if (bin.Length > 0)
{
Images = System.Drawing.Image.FromStream(new MemoryStream(bin)).GetThumbnailImage(200, 200, null, IntPtr.Zero);
album = file12.Tag.Album;
}
}
Please Help me

Just put that code in a controller method, image will be loaded asynchronously (in this example controller method accepts file name as parameter, it may not be your case):
public ActionResult GetImage(string file)
{
var file12 = TagLib.File.Create(file);
if (file12.Tag.Pictures.Length >= 1)
{
string fileName = Path.ChangeExtension(
Path.GetFileName(file), ".jpg");
return base.File(
(byte[])(file12.Tag.Pictures[0].Data.Data),
"image/jpeg", fileName);
}
// You have to handle this case
return null;
}
Controller.File() method will do all the dirty job for you. For clarity in this example I omitted rescaling, just copy & paste your code there if needed. Please note you have to return something when no image is not available (a default thumbnail?), you may even return a HTTP error with:
return HttpNotFound();
Your HTML will be for example like this:
<img
src='#Url.Action("GetImage", new { file = "filenamehere.mp3" })'
alt='thumbnail' />
Please note that here I assumed your image is in JPG format, if it's not you may need to convert it to a known format to return proper MIME type (to detect MIME type from byte stream is possible too, check this post here on SO).

You can try Base64 converted string to get Image with Ajax or regular call
FYI.
http://www.codeproject.com/Articles/201767/Load-Base64-Images-using-jQuery-and-MVC
Hope helps.

I have Choose an Another option for display AlbumArt of the Mp3 file.
Create Windows Form Application for Tracking mp3 file Album Art.
var filename = TagLib.File.Create(file);
if (filename.Tag.Pictures.Length >= 1)
{
var bin = (byte[])(filename.Tag.Pictures[0].Data.Data);
if (bin.Length > 0)
{
Images = Image.FromStream(new MemoryStream(bin)).GetThumbnailImage(800, 800, null, IntPtr.Zero);
PreviewPictureBox.Image = Images;
PreviewPictureBox.Image.Save("C:/Users/v-manshr/Desktop/MyMusicPlayer/MyMusicPlayer/AlbumImage/"+filename.Tag.Album+".jpg");
PreviewPictureBox.Visible = false;
}
}
Here PreviewPictureBox is a WindwosFormComtrol.
now i got a mp3 file album art, save in one location.now in MVC controller i copy that all files in to my Visual Studio Local Folders.Using (File.Copy).now u Display in Viewr.using Image Src tag

Creating an Epub file with a Zip library

HI All,
I am trying to zip up an Epub file i have made using c#
Things I have tried
Dot Net Zip http://dotnetzip.codeplex.com/
- DotNetZip works but epubcheck fails the resulting file (**see edit below)
ZipStorer zipstorer.codeplex.com
- creates an epub file that passes validation but the file won't open in Adobe Digital Editions
7 zip
- I have not tried this using c# but when i zip the file using there interface it tells me that the mimetype file name has a length of 9 and it should be 8
In all cases the mimetype file is the first file added to the archive and is not compressed
The Epub validator that I'am using is epubcheck http://code.google.com/p/epubcheck/
if anyone has succesfully zipped an epub file with one of these libraries please let me know how or if anyone has zipped an epub file successfully with any other open source zipping api that would also work.
EDIT
DotNetZip works, see accepted answer below.

If you need to control the order of the entries in the ZIP file, you can use DotNetZip and the ZipOutputStream.
You said you tried DotNetZip and it (the epub validator) gave you an error complaining about the mime type thing. This is probably because you used the ZipFile type within DotNetZip. If you use ZipOutputStream, you can control the ordering of the zip entries, which is apparently important for epub (I don't know the format, just surmising).
EDIT
I just checked, and the epub page on Wikipedia describes how you need to format the .epub file. It says that the mimetype file must contain specific text, must be uncompressed and unencrypted, and must appear as the first file in the ZIP archive.
Using ZipOutputStream, you would do this by setting CompressionLevel = None on that particular ZipEntry - that value is not the default.
Here's some sample code:
private void Zipup()
{
string _outputFileName = "Fargle.epub";
using (FileStream fs = File.Open(_outputFileName, FileMode.Create, FileAccess.ReadWrite ))
{
using (var output= new ZipOutputStream(fs))
{
var e = output.PutNextEntry("mimetype");
e.CompressionLevel = CompressionLevel.None;
byte[] buffer= System.Text.Encoding.ASCII.GetBytes("application/epub+zip");
output.Write(buffer,0,buffer.Length);
output.PutNextEntry("META-INF/container.xml");
WriteExistingFile(output, "META-INF/container.xml");
output.PutNextEntry("OPS/"); // another directory
output.PutNextEntry("OPS/whatever.xhtml");
WriteExistingFile(output, "OPS/whatever.xhtml");
// ...
}
}
}
private void WriteExistingFile(Stream output, string filename)
{
using (FileStream fs = File.Open(fileName, FileMode.Read))
{
int n = -1;
byte[] buffer = new byte[2048];
while ((n = fs.Read(buffer,0,buffer.Length)) > 0)
{
output.Write(buffer,0,n);
}
}
}
See the documentation for ZipOutputStream here.

Why not make life easier?
private void IonicZip()
{
string sourcePath = "C:\\pulications\\";
string fileName = "filename.epub";
// Creating ZIP file and writing mimetype
using (ZipOutputStream zs = new ZipOutputStream(sourcePath + fileName))
{
var o = zs.PutNextEntry("mimetype");
o.CompressionLevel = CompressionLevel.None;
byte[] mimetype = System.Text.Encoding.ASCII.GetBytes("application/epub+zip");
zs.Write(mimetype, 0, mimetype.Length);
}
// Adding META-INF and OEPBS folders including files
using (ZipFile zip = new ZipFile(sourcePath + fileName))
{
zip.AddDirectory(sourcePath + "META-INF", "META-INF");
zip.AddDirectory(sourcePath + "OEBPS", "OEBPS");
zip.Save();
}
}

For anyone like me who's searching for other ways to do this, I would like to add that the ZipStorer class from Jaime Olivares is a great alternative. You can copy the code right into your project, and it's very easy to choose between 'deflate' and 'store'.
https://github.com/jaime-olivares/zipstorer
Here's my code for creating an EPUB:
Dictionary<string, string> FilesToZip = new Dictionary<string, string>()
{
{ ConfigPath + #"mimetype", #"mimetype"},
{ ConfigPath + #"container.xml", #"META-INF/container.xml" },
{ OutputFolder + Name.Output_OPF_Name, #"OEBPS/" + Name.Output_OPF_Name},
{ OutputFolder + Name.Output_XHTML_Name, #"OEBPS/" + Name.Output_XHTML_Name},
{ ConfigPath + #"style.css", #"OEBPS/style.css"},
{ OutputFolder + Name.Output_NCX_Name, #"OEBPS/" + Name.Output_NCX_Name}
};
using (ZipStorer EPUB = ZipStorer.Create(OutputFolder + "book.epub", ""))
{
bool First = true;
foreach (KeyValuePair<string, string> File in FilesToZip)
{
if (First) { EPUB.AddFile(ZipStorer.Compression.Store, File.Key, File.Value, ""); First = false; }
else EPUB.AddFile(ZipStorer.Compression.Deflate, File.Key, File.Value, "");
}
}
This code creates a perfectly valid EPUB file. However, if you don't need to worry about validation, it seems most eReaders will accept an EPUB with a 'deflate' mimetype. So my previous code using .NET's ZipArchive produced EPUBs that worked in Adobe Digital Editions and a PocketBook.