Setting MimeType in C#

Question

Is there a better way of setting mimetypes in C# than the one I am trying to do thanks in advance.

static String MimeType(string filePath)
{
  String ret = null;
  FileInfo file = new FileInfo(filePath);

  if (file.Extension.ToUpper() == ".PDF")
  {
    ret = "application/pdf";
  }
  else if (file.Extension.ToUpper() == ".JPG" || file.Extension.ToUpper() == ".JPEG")
  {
    ret = "image/jpeg";
  }
  else if (file.Extension.ToUpper() == ".PNG")
  {
    ret = "image/png";
  }
  else if (file.Extension.ToUpper() == ".GIF")
  {
    ret = "image/gif";
  }
  else if (file.Extension.ToUpper() == ".TIFF" || file.Extension.ToUpper() == ".TIF")
  {
    ret = "image/tiff";
  }
  else
  {
    ret = "image/" + file.Extension.Replace(".", "");
  }

  return ret;
}

I still don't understand why the large collection of MIME types which MS uses in System.Web hasn't been made available my making the internal class public... everyone is coding their own method to get the mime type of a file name and only very few are actually doing it right. — Lucero, Jun 24 '10 at 16:05
possible duplicate of [How do I get the MIME type of a file being requested in ASP.NET C#?](http://stackoverflow.com/questions/1302264/how-do-i-get-the-mime-type-of-a-file-being-requested-in-asp-net-c) — Lucero, Jun 24 '10 at 16:08
There's also [Using .NET, how can you find the mime type of a file based on the file signature not the extension. ](http://stackoverflow.com/questions/58510/using-net-how-can-you-find-the-mime-type-of-a-file-based-on-the-file-signature) — Roman, Jun 24 '10 at 16:12

score 15 · Accepted Answer · answered Jun 24 '10 at 16:06

15

I got this from this blogpost:

private string GetMimeType (string fileName)
{
    string mimeType = "application/unknown";
    string ext = System.IO.Path.GetExtension(fileName).ToLower();
    Microsoft.Win32.RegistryKey regKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext);
    if (regKey != null && regKey.GetValue("Content Type") != null)
    mimeType = regKey.GetValue("Content Type").ToString();
    return mimeType;
}

answered Jun 24 '10 at 16:06

VoodooChild

9,776
8
66
99

2

I was going to suggest the registry. However if you're running in partial trust mode I think you need to explicitly grant registry access else it'll be refused. I'd probably also cache the requests in your app rather than query every time but that's more from general unease of calling out to the registry rather than hard data. Maybe also worth point out: rather than app/unknown, IIS will refuse to serve a file if there's no registry Content Type. – Rup Jun 24 '10 at 16:12

Manoochehr Dadashi · Answer 2 · 2015-11-23T18:17:20.617

11

Just this one line is needed to do this.

System.Web.MimeMapping.GetMimeMapping(FileName)

Note: It's .NET 4.5+ only

edited Nov 23 '15 at 18:17

answered Jan 02 '15 at 17:24

Manoochehr Dadashi

715
1
10
28

You might want to include Rup's comment in your answer (link to the docs and that it's 4.5+). – Roman Jan 16 '15 at 15:46

score 7 · Answer 3 · answered Jun 24 '10 at 16:29

A Dictionary<String,String> may prove to be clearer.

private static Dictionary<String, String> mtypes = new Dictionary<string, string> {
        {".PDF", "application/pdf" },
        {".JPG", "image/jpeg"},
        {".PNG", "image/png"},
        {".GIF", "image/gif"},
        {".TIFF","image/tiff"},
        {".TIF", "image/tiff"}
    };

static String MimeType(String filePath)
{
    System.IO.FileInfo file = new System.IO.FileInfo(filePath);
    String filetype = file.Extension.ToUpper();
    if(mtypes.Keys.Contains<String>(filetype))
        return mtypes[filetype];
    return "image/" + filetype.Replace(".", "").ToLower();
}

Wim · Answer 4 · 2010-06-24T16:12:52.090

4

If you don't have registry access or don't want to use the registry, you could always use a Dictionary for that.

Dictionary<string,string> mimeTypes = new Dictionary<string,string>() { 
 { ".PDF","application/pdf"},
 { ".JPG", "image/jpeg" },
 { ".JPEG", "image/jpeg" } }; // and so on

Then use:

string mimeType = mimeTypes[fileExtension];

In addition, you could store these mappings in an XML file and cache them with a file dependency, rather than keeping them in your code.

edited Jun 24 '10 at 16:12

answered Jun 24 '10 at 16:06

Wim

11,998
1
34
57

1

Still needs to be hardcoded though, I think the question is about using an existing API rather than having yet another implementation. – Roman Jun 24 '10 at 16:08

Setting MimeType in C#

4 Answers4

Linked