Asp.Net MVC Bundling, best way to detect missing file

Question

I've just chased a bug that was due to a missing javascript file, it was failing silently.

The minified version of the file was present but not the full version, a link isn't rendered on the client (which I was expecting) but I don't get an exception either. I'd like to know if the file isn't present.

(just to be clear, the bundle didn't try to included the minified version, it tried to include the full version, but the minified version was present in the script directory)

Do I have to write something custom to detect this or does MVC have anything built in to report this?

thanks

Answer 1

I came up to using the following extension methods for Bundle:

public static class BundleHelper
{
    [Conditional("DEBUG")] // remove this attribute to validate bundles in production too
    private static void CheckExistence(string virtualPath)
    {
        int i = virtualPath.LastIndexOf('/');
        string path = HostingEnvironment.MapPath(virtualPath.Substring(0, i));
        string fileName = virtualPath.Substring(i + 1);

        bool found = Directory.Exists(path);

        if (found)
        {
            if (fileName.Contains("{version}"))
            {
                var re = new Regex(fileName.Replace(".", @"\.").Replace("{version}", @"(\d+(?:\.\d+){1,3})"));
                fileName = fileName.Replace("{version}", "*");
                found = Directory.EnumerateFiles(path, fileName).FirstOrDefault(file => re.IsMatch(file)) != null;
            }
            else // fileName may contain '*'
                found = Directory.EnumerateFiles(path, fileName).FirstOrDefault() != null;
        }

        if (!found)
            throw new ApplicationException(String.Format("Bundle resource '{0}' not found", virtualPath));
    }

    public static Bundle IncludeExisting(this Bundle bundle, params string[] virtualPaths)
    {
        foreach (string virtualPath in virtualPaths)
            CheckExistence(virtualPath);

        return bundle.Include(virtualPaths);
    }

    public static Bundle IncludeExisting(this Bundle bundle, string virtualPath, params IItemTransform[] transforms)
    {
        CheckExistence(virtualPath);
        return bundle.Include(virtualPath, transforms);
    }
}

This way you don't have to call your helper method PreCheck() explicitly. It also supports ASP.NET's wildcards {version} and *:

bundles.Add(new ScriptBundle("~/test")
    .IncludeExisting("~/Scripts/jquery/jquery-{version}.js")
    .IncludeExisting("~/Scripts/lib*")
    .IncludeExisting("~/Scripts/model.js")
    );