MVC4 StyleBundle not resolving images

Question

My question is similar to this:

ASP.NET MVC 4 Minification & Background Images

Except that I want to stick with MVC's own bundling if I can. I'm having a brain crash trying to figure out what the correct pattern is for specifying style bundles such that standalone css and image sets such as jQuery UI work.

I have a typical MVC site structure with /Content/css/ which contains my base CSS such as styles.css. Within that css folder I also have subfolders such as /jquery-ui which contains its CSS file plus an /images folder. Image paths in the jQuery UI CSS are relative to that folder and I don't want to mess with them.

As I understand it, when I specify a StyleBundle I need to specify a virtual path which does not also match a real content path, because (assuming I'm ignoring routes to Content) IIS would then try to resolve that path as a physical file. So I'm specifying:

bundles.Add(new StyleBundle("~/Content/styles/jquery-ui")
       .Include("~/Content/css/jquery-ui/*.css"));

rendered using:

@Styles.Render("~/Content/styles/jquery-ui")

I can see the request going out to:

http://localhost/MySite/Content/styles/jquery-ui?v=nL_6HPFtzoqrts9nwrtjq0VQFYnhMjY5EopXsK8cxmg1

This is returning the correct, minified CSS response. But then the browser sends a request for a relatively linked image as:

http://localhost/MySite/Content/styles/images/ui-bg_highlight-soft_100_eeeeee_1x100.png

Which is a 404.

I understand that the last part of my URL jquery-ui is an extensionless URL, a handler for my bundle, so I can see why the relative request for the image is simply /styles/images/.

So my question is what is the correct way of handling this situation?

Answer 1

As of v1.1.0-alpha1 (pre release package) the framework uses the VirtualPathProvider to access files rather than touching the physical file system.

The updated transformer can be seen below:

public class StyleRelativePathTransform
    : IBundleTransform
{
    public void Process(BundleContext context, BundleResponse response)
    {
        Regex pattern = new Regex(@"url\s*\(\s*([""']?)([^:)]+)\1\s*\)", RegexOptions.IgnoreCase);

        response.Content = string.Empty;

        // open each of the files
        foreach (var file in response.Files)
        {
            using (var reader = new StreamReader(file.Open()))
            {
                var contents = reader.ReadToEnd();

                // apply the RegEx to the file (to change relative paths)
                var matches = pattern.Matches(contents);

                if (matches.Count > 0)
                {
                    var directoryPath = VirtualPathUtility.GetDirectory(file.VirtualPath);

                    foreach (Match match in matches)
                    {
                        // this is a path that is relative to the CSS file
                        var imageRelativePath = match.Groups[2].Value;

                        // get the image virtual path
                        var imageVirtualPath = VirtualPathUtility.Combine(directoryPath, imageRelativePath);

                        // convert the image virtual path to absolute
                        var quote = match.Groups[1].Value;
                        var replace = String.Format("url({0}{1}{0})", quote, VirtualPathUtility.ToAbsolute(imageVirtualPath));
                        contents = contents.Replace(match.Groups[0].Value, replace);
                    }

                }
                // copy the result into the response.
                response.Content = String.Format("{0}\r\n{1}", response.Content, contents);
            }
        }
    }
}

Answer 2

Here is a Bundle Transform that will replace css urls with urls relative to that css file. Just add it to your bundle and it should fix the issue.

public class CssUrlTransform: IBundleTransform
{
    public void Process(BundleContext context, BundleResponse response) {
        Regex exp = new Regex(@"url\([^\)]+\)", RegexOptions.IgnoreCase | RegexOptions.Singleline);
        foreach (FileInfo css in response.Files) {
            string cssAppRelativePath = css.FullName.Replace(context.HttpContext.Request.PhysicalApplicationPath, context.HttpContext.Request.ApplicationPath).Replace(Path.DirectorySeparatorChar, '/');
            string cssDir = cssAppRelativePath.Substring(0, cssAppRelativePath.LastIndexOf('/'));
            response.Content = exp.Replace(response.Content, m => TransformUrl(m, cssDir));
        }
    }


    private string TransformUrl(Match match, string cssDir) {
        string url = match.Value.Substring(4, match.Length - 5).Trim('\'', '"');

        if (url.StartsWith("http://") || url.StartsWith("data:image")) return match.Value;

        if (!url.StartsWith("/"))
            url = string.Format("{0}/{1}", cssDir, url);

        return string.Format("url({0})", url);
    }

}

Answer 3

Although Chris Baxter's answer helps with original problem, it doesn't work in my case when application is hosted in virtual directory. After investigating the options, I finished with DIY solution.

ProperStyleBundle class includes code borrowed from original CssRewriteUrlTransform to properly transform relative paths within virtual directory. It also throws if file doesn't exist and prevents reordering of files in the bundle (code taken from BetterStyleBundle).

using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.Optimization;
using System.Linq;

namespace MyNamespace
{
    public class ProperStyleBundle : StyleBundle
    {
        public override IBundleOrderer Orderer
        {
            get { return new NonOrderingBundleOrderer(); }
            set { throw new Exception( "Unable to override Non-Ordered bundler" ); }
        }

        public ProperStyleBundle( string virtualPath ) : base( virtualPath ) {}

        public ProperStyleBundle( string virtualPath, string cdnPath ) : base( virtualPath, cdnPath ) {}

        public override Bundle Include( params string[] virtualPaths )
        {
            foreach ( var virtualPath in virtualPaths ) {
                this.Include( virtualPath );
            }
            return this;
        }

        public override Bundle Include( string virtualPath, params IItemTransform[] transforms )
        {
            var realPath = System.Web.Hosting.HostingEnvironment.MapPath( virtualPath );
            if( !File.Exists( realPath ) )
            {
                throw new FileNotFoundException( "Virtual path not found: " + virtualPath );
            }
            var trans = new List<IItemTransform>( transforms ).Union( new[] { new ProperCssRewriteUrlTransform( virtualPath ) } ).ToArray();
            return base.Include( virtualPath, trans );
        }

        // This provides files in the same order as they have been added. 
        private class NonOrderingBundleOrderer : IBundleOrderer
        {
            public IEnumerable<BundleFile> OrderFiles( BundleContext context, IEnumerable<BundleFile> files )
            {
                return files;
            }
        }

        private class ProperCssRewriteUrlTransform : IItemTransform
        {
            private readonly string _basePath;

            public ProperCssRewriteUrlTransform( string basePath )
            {
                _basePath = basePath.EndsWith( "/" ) ? basePath : VirtualPathUtility.GetDirectory( basePath );
            }

            public string Process( string includedVirtualPath, string input )
            {
                if ( includedVirtualPath == null ) {
                    throw new ArgumentNullException( "includedVirtualPath" );
                }
                return ConvertUrlsToAbsolute( _basePath, input );
            }

            private static string RebaseUrlToAbsolute( string baseUrl, string url )
            {
                if ( string.IsNullOrWhiteSpace( url )
                     || string.IsNullOrWhiteSpace( baseUrl )
                     || url.StartsWith( "/", StringComparison.OrdinalIgnoreCase )
                     || url.StartsWith( "data:", StringComparison.OrdinalIgnoreCase )
                    ) {
                    return url;
                }
                if ( !baseUrl.EndsWith( "/", StringComparison.OrdinalIgnoreCase ) ) {
                    baseUrl = baseUrl + "/";
                }
                return VirtualPathUtility.ToAbsolute( baseUrl + url );
            }

            private static string ConvertUrlsToAbsolute( string baseUrl, string content )
            {
                if ( string.IsNullOrWhiteSpace( content ) ) {
                    return content;
                }
                return new Regex( "url\\(['\"]?(?<url>[^)]+?)['\"]?\\)" )
                    .Replace( content, ( match =>
                                         "url(" + RebaseUrlToAbsolute( baseUrl, match.Groups["url"].Value ) + ")" ) );
            }
        }
    }
}

Use it like StyleBundle:

bundles.Add( new ProperStyleBundle( "~/styles/ui" )
    .Include( "~/Content/Themes/cm_default/style.css" )
    .Include( "~/Content/themes/custom-theme/jquery-ui-1.8.23.custom.css" )
    .Include( "~/Content/DataTables-1.9.4/media/css/jquery.dataTables.css" )
    .Include( "~/Content/DataTables-1.9.4/extras/TableTools/media/css/TableTools.css" ) );

Answer 4

Grinn / ThePirat solution works well.

I did not like that it new'd the Include method on bundle, and that it created temporary files in the content directory. (they ended up getting checked in, deployed, then the service wouldn't start!)

So to follow the design of Bundling, I elected to perform essentially the same code, but in an IBundleTransform implementation::

class StyleRelativePathTransform
    : IBundleTransform
{
    public StyleRelativePathTransform()
    {
    }

    public void Process(BundleContext context, BundleResponse response)
    {
        response.Content = String.Empty;

        Regex pattern = new Regex(@"url\s*\(\s*([""']?)([^:)]+)\1\s*\)", RegexOptions.IgnoreCase);
        // open each of the files
        foreach (FileInfo cssFileInfo in response.Files)
        {
            if (cssFileInfo.Exists)
            {
                // apply the RegEx to the file (to change relative paths)
                string contents = File.ReadAllText(cssFileInfo.FullName);
                MatchCollection matches = pattern.Matches(contents);
                // Ignore the file if no match 
                if (matches.Count > 0)
                {
                    string cssFilePath = cssFileInfo.DirectoryName;
                    string cssVirtualPath = context.HttpContext.RelativeFromAbsolutePath(cssFilePath);
                    foreach (Match match in matches)
                    {
                        // this is a path that is relative to the CSS file
                        string relativeToCSS = match.Groups[2].Value;
                        // combine the relative path to the cssAbsolute
                        string absoluteToUrl = Path.GetFullPath(Path.Combine(cssFilePath, relativeToCSS));

                        // make this server relative
                        string serverRelativeUrl = context.HttpContext.RelativeFromAbsolutePath(absoluteToUrl);

                        string quote = match.Groups[1].Value;
                        string replace = String.Format("url({0}{1}{0})", quote, serverRelativeUrl);
                        contents = contents.Replace(match.Groups[0].Value, replace);
                    }
                }
                // copy the result into the response.
                response.Content = String.Format("{0}\r\n{1}", response.Content, contents);
            }
        }
    }
}

And then wrapped this up in a Bundle Implemetation:

public class StyleImagePathBundle 
    : Bundle
{
    public StyleImagePathBundle(string virtualPath)
        : base(virtualPath)
    {
        base.Transforms.Add(new StyleRelativePathTransform());
        base.Transforms.Add(new CssMinify());
    }

    public StyleImagePathBundle(string virtualPath, string cdnPath)
        : base(virtualPath, cdnPath)
    {
        base.Transforms.Add(new StyleRelativePathTransform());
        base.Transforms.Add(new CssMinify());
    }
}

Sample Usage:

static void RegisterBundles(BundleCollection bundles)
{
...
    bundles.Add(new StyleImagePathBundle("~/bundles/Bootstrap")
            .Include(
                "~/Content/css/bootstrap.css",
                "~/Content/css/bootstrap-responsive.css",
                "~/Content/css/jquery.fancybox.css",
                "~/Content/css/style.css",
                "~/Content/css/error.css",
                "~/Content/validation.css"
            ));

Here is my extension method for RelativeFromAbsolutePath:

   public static string RelativeFromAbsolutePath(this HttpContextBase context, string path)
    {
        var request = context.Request;
        var applicationPath = request.PhysicalApplicationPath;
        var virtualDir = request.ApplicationPath;
        virtualDir = virtualDir == "/" ? virtualDir : (virtualDir + "/");
        return path.Replace(applicationPath, virtualDir).Replace(@"\", "/");
    }

Answer 5

CssRewriteUrlTransform fixed my problem.
If your code still not loading images after using CssRewriteUrlTransform, then change your css filename's from:

.Include("~/Content/jquery/jquery-ui-1.10.3.custom.css", new CssRewriteUrlTransform())

To:

.Include("~/Content/jquery/jquery-ui.css", new CssRewriteUrlTransform())

Someway .(dots) are not recognizing in url.

Answer 6

You can simply add another level of depth to your virtual bundle path

    //Two levels deep bundle path so that paths are maintained after minification
    bundles.Add(new StyleBundle("~/Content/css/css").Include("~/Content/bootstrap/bootstrap.css", "~/Content/site.css"));

This is a super low-tech answer and kind of a hack but it works and won't require any pre-processing. Given the length and complexity of some of these answers I prefer doing it this way.