Using MimeMapping in ASP.NET Core

Question

I'm trying to move my old mvc5 project to asp net core. Old code was:

public string ContentType
{
    get
    {
        if (!string.IsNullOrEmpty(FileName))
            return MimeMapping.GetMimeMapping(FileName);
        return null;
    }
}

Error is

The name 'MimeMapping' does not exist in the current context

Goble

Answer 1

The following code should work:

string contentType;
new FileExtensionContentTypeProvider().TryGetContentType(FileName, out contentType);
return contentType ?? "application/octet-stream";

Consternation

@NickMuller is 'System.Net.Mime' supported in the netcore world? – Hartzel

@BrennenSprimont: Nope, it's not. Was working at a project targeting .NET 4.x, and I guess I got confused. I've deleted the comment, because I couldn't edit it anymore. – Culmination

note: In ASPNETCORE 2.1, this code requires adding Nuget Package: 'Microsoft.AspNetCore.StaticFiles', and 'using Microsoft.AspNetCore.StaticFiles;' declaration. – Glenoid

Note: FileExtensionContentTypeProvider provides mimetype mapping for only a subset of mimetypes compared to MimeMapping.GetMimeMapping(). E.g. current visio types like .vsdx, .vsdm,... cannot be mapped with it! – Protective

Answer 2

There is a NuGet package MimeTypes which works with .Net Core projects as an alternative to FileExtensionContentTypeProvider. I'm not aware of any other mime-type resolver package, which works with .Net Core (at least so far).

The usage is simple:

string fileName = "trial.jpg";
string mime = MimeKit.MimeTypes.GetMimeType(fileName);

Daisy

Simple = good ! First tried Mark's answer but you need to reference another dll. This approach just has a single purpose c# file that is added as a content file and is referenceable as shown. – Plug

With new version nuget.org/packages/MimeTypes , its just MimeTypes.GetMimeType(filename) – Repulsive

Now that Microsoft.AspNetCore.StaticFiles is deprecated, this is a better solution. – Steven

Answer 3

System.Web is not moved to .NetCore because it relies too much on API's that are platform specific. You could take a look at Microsoft reference source:

https://github.com/Microsoft/referencesource/blob/master/System.Web/MimeMapping.cs

The code is subject to a MIT license.

Gruel

After looking for alternate answers to that, there is none. The only better way would be to automatically generate C# code based on a static list. – Reach