Site.less' is a physical path, but a virtual path was expected

Question

I all I am using DotLess with a LessTransformer.cs I found online, In my MVC 4 project.

using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Web.Optimization;
using MyNamespace.Infrastructure.Bundler;
using dotless.Core.configuration;

namespace MyNameSpace.Infrastructure.Transformers.Less
{
    public class LessTransform : IBundleTransform
    {
        private readonly DotlessConfiguration _configuration;

        public LessTransform(DotlessConfiguration configuration)
        {
            _configuration = configuration;
        }

        public LessTransform()
            : this(DotlessConfiguration.GetDefaultWeb())
        { }

        public void Process(BundleContext context, BundleResponse response)
        {
            var builder = new StringBuilder();

            _configuration.MinifyOutput         = false;
            _configuration.ImportAllFilesAsLess = true;
            _configuration.CacheEnabled         = false;
            _configuration.LessSource           = typeof(VirtualFileReader);

            foreach (var file in response.Files)
            {
                if (!File.Exists(file.FullName))
                {
                    continue;
                }

                var content = ResolveImports(file);

                builder.AppendLine((_configuration.Web) ?
                                    dotless.Core.LessWeb.Parse(content, _configuration)
                                    : dotless.Core.Less.Parse(content, _configuration));
            }

            response.ContentType = "text/css";
            response.Content = builder.ToString();
        }

        private static readonly Regex SLessImportRegex =
            new Regex("@import [\"|'](.+)[\"|'];", RegexOptions.Compiled);

        private static string ResolveImports(FileInfo file)
        {
            var content = File.ReadAllText(file.FullName, Encoding.UTF8);

            return SLessImportRegex.Replace(
                content,
                match =>
                {
                    var import = match.Groups[1].Value;

                    // Is absolute path?
                    Uri uri;
                    if (Uri.TryCreate(import, UriKind.Absolute, out uri))
                    {
                        return match.Value;
                    }

                    var path = Path.Combine(file.Directory.FullName, import);

                    if (!File.Exists(path))
                    {
                        throw new ApplicationException(string.Concat("Unable to resolve import ", import));
                    }
                    return match.Value.Replace(import, path);
                });
        }
    }
}

I have since added to this

_configuration.MinifyOutput         = false;
_configuration.ImportAllFilesAsLess = true;
_configuration.CacheEnabled         = false;
_configuration.LessSource           = typeof(VirtualFileReader);



using System.IO;
using System.Web.Hosting;
using dotless.Core.Input;

namespace MyNamespace.Infrastructure.Bundler
{
    internal sealed class VirtualFileReader : IFileReader
    {
        public byte[] GetBinaryFileContents(string fileName)
        {
            fileName = GetFullPath(fileName);
            return File.ReadAllBytes(fileName);
        }

        public string GetFileContents(string fileName)
        {
            fileName = GetFullPath(fileName);
            return File.ReadAllText(fileName);
        }

        public bool DoesFileExist(string fileName)
        {
            fileName = GetFullPath(fileName);
            return File.Exists(fileName);
        }

        private static string GetFullPath(string path)
        {
            return HostingEnvironment.MapPath("\\Content\\css\\" + path);
        }
    }
}

I have a Less file

@import url('LESS\Site.less');
@import url('LESS\Site.Main.less');

body {
    #featured-posts {
        clear:both;
    }
}

@media all and (max-width:320px) {
   @import url('LESS\Site.Mobile.less');
}

(Which I have tried various paths for the imports and /w and /wo function notation url()

Which is all pulled in my BundleConfig

    Bundle siteStyles = new      StyleBundle("~/bundles/css").Include("~/Content/css/Main.less");
    siteStyles.Transforms.Add(new LessTransform());
    siteStyles.Transforms.Add(new CssMinify());
    bundles.Add(siteStyles);

before I added the VirtualFileReader I was getting the error:-

C:/SourceControl/Git/MyNameSpace/MyNameSpace/Content/css/LESS/Site.less' is a physical path, but a virtual path was expected.

since I adding it I get simply the value is null on dotless.Core.LessWeb.Parse(content, _configuration)

it always blow up on this line, granted I've been a bit gun-ho implementing this less stuff and dotless because I haven't used either before, but I can't seem to find any good solid documentations/tutorials on it. So if you could help me out with my error that would be great and point me in the direction of some good tutorials on the subject I would be very grateful.

[EDIT] adding details on less files and file structure.

My File structure is 

Content/css/Main.less
Content/css/LESS/Site.less
Content/css/LESS/Mobile.less

etc... TIA.

p.s. don't worry about the MyNamespace/MyNamespace stuff I've just shortened it all for clarity.

Answer 1

I don't understand why you are using the custom transformer.

LESS specification says that if you use the following syntax the file will be bundled automatically:

@import "LESS/Site";

It works perfectly for me, I don't need any custom transformers, only the standard dotless package. To enable minification you need this setting in the web.config:

<dotless minifyCss="true" cache="true" web="true" />

I have around 30 imports of components and sub components and the output is a single minified file.

I suggest you to not use the style bundle but to point directly to your less file:

<link href="~/Content/css/main.less" rel="stylesheet" />

The dotless http handler will kick in, convert the less to css and cache it for subsequent requests