Guide to getting LESS working with Twitter Bootstrap in MVC 5

[Kalint]

What a pain in the ass to figure out when many of the other guides are for older versions or use dead projects.  I'm throwing this up in case anyone else wants to get LESS in MVC5.

 

What I'll be using:

Visual Studio 2013 Professional (Express versions probably work fine)

Web Essentials 2013 (A free extension, not required but nice to have)

Twitter Bootstrap (Just awesome)

 

So... LET THE FUN BEGIN

 

1.  Start with a new project then go to nuget and let's download what we need.  If you are unfamiliar with nuget, its an awesome package management service.

Go to Tools > Library Package Manager > Manage NuGet Packages for solution...

 

2.  Since Visual Studio 2013's release, there are already updates you can run on your project.

Click Updates and for the purpose of this guide, update:

> jQuery

> Microsoft ASP.NET Web Optimization Framework

> ANTLRv3

 

After this is done  Click Online on the left side then in the search box type "Bootstrap Less Source".  The current version is 3.0.2.

 

You'll see in the dependencies that LESS will also be installed. Install it.

 

Next, search for Bundle Transformer: LESS, Install this.

 

Finally, we need a javascript engine.  Bundle Transformer will give you a head up about this and give you two options.  Either MSIE or V8.  I'll be installing V8 because it sounds cool.

 

Search for V8 and the first one should be "JavaScript Engine Switcher for .Net: V8", install it.

 

3.  Associate V8 with Bundle Transformer (BT).

BT needs to know which engine to use so it can compile your LESS files.  So in your solution, scroll to the bottom and open "Web.Config".  If your config file looks like hell, Visual Studio has the best button of any IDE.  Click Edit > Advanced > Format Document.  SURPRISE! VS retabbed the structured XML!

 

To associate add the <less> block:

<bundleTransformer xmlns="http://tempuri.org/BundleTransformer.Configuration.xsd">
    <less useNativeMinification="false" ieCompat="true" strictMath="false" strictUnits="false" dumpLineNumbers="None">
      <jsEngine name="V8JsEngine" />
    </less>
    <core>
      <css>
        <minifiers>
          <add name="NullMinifier" type="BundleTransformer.Core.Minifiers.NullMinifier, BundleTransformer.Core" />
        </minifiers>
        <translators>

Save it.

 

4. Creating your bundles

Bundles are the new Jesus of the internet.  They simply make life easier.  For certain types like .js, MVC allows wildcards which is awesome.

 

Go to App_Start > BundleConfig.cs

 

First we need to type in our using statements so the file knows which libraries to use.

using System.Web.Optimization;
using BundleTransformer.Core.Builders;
using BundleTransformer.Core.Orderers;
using BundleTransformer.Core.Transformers;

In the BT documentation there is another way to build your bundles but for the purpose of this, I'll be doing it the long way.

 

Now everything inside the scope of RegisterBundles, delete (This is entirely optional.)

 

Now within the same scope, create new instances of variables.

            // Variables
            bundles.UseCdn = true;
            var nullBuilder = new NullBuilder();
            var cssTransformer = new CssTransformer();
            var jsTransformer = new JsTransformer();
            var nullOrderer = new NullOrderer();

Next, associating our scripts

            // JavaScript

            // jQuery
            var jquery = new Bundle("~/bundles/jquery").Include(
                "~/Scripts/jquery-{version}.js");
            jquery.Builder = nullBuilder;
            jquery.Transforms.Add(jsTransformer);
            jquery.Orderer = nullOrderer;

            bundles.Add(jquery);

            // Modernizr
            var modernizr = new Bundle("~/bundles/modernizr").Include(
                "~/Scripts/modernizr-2.6.2.js");
            modernizr.Builder = nullBuilder;
            modernizr.Transforms.Add(jsTransformer);
            modernizr.Orderer = nullOrderer;

            bundles.Add(modernizr);

            // Scripts
            var js = new Bundle("~/bundles/js").Include(
                "~/Scripts/bootstrap.min.js",
                "~/Scripts/myScripts.js");
            js.Builder = nullBuilder;
            js.Transforms.Add(jsTransformer);
            js.Orderer = nullOrderer;

            bundles.Add(js);

            // POST: Validation
            var jqueryVal = new Bundle("~/bundles/jqueryval").Include(
                "~/Scripts/jquery.validate.unobtrusive.min.js",
                "~/Scripts/jquery.validate.min.js");
            jqueryVal.Builder = nullBuilder;
            jqueryVal.Transforms.Add(jsTransformer);
            jqueryVal.Orderer = nullOrderer;

            bundles.Add(jqueryVal);

jQuery should always go first.  Next Styles.  What's nice about this is at compile time it automatically minifies the CSS.

            // Styles
            var css = new Bundle("~/bundles/css").Include(
                "~/Content/bootstrap/bootstrap.less");
            css.Builder = nullBuilder;
            css.Transforms.Add(cssTransformer);
            css.Transforms.Add(new CssMinify());
            css.Orderer = nullOrderer;

            bundles.Add(css);

Finally, we tell the bundles to optimize.

            BundleTable.EnableOptimizations = true;

Ok so let's run our project quick!

 

OH GOD WHAT HAPPENED?!!!  ohhh the humanity!  The styles are dead!!  ohhhhhh!!!!!!!!!

 

Hang on!  On to step 5!

 

5. Associate our bundles with the layout

Go to Views > Shared > _Layout.cshtml

 

In the header add:

    <!-- styles -->
    @Styles.Render("~/bundles/css")
    <!-- /styles -->
    @Scripts.Render("~/bundles/modernizr")

and down on the bottom of the body add:

    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/js")

Compile the project again and whaddya know LESS WORKS!  Now you can configure your variables using LESS and save time!

 

KNOWN ISSUES:

 

Google is not happy with query strings.

2 Bad requests atm, tomorrow may have update.

Modernizr is not production version, get that at their website.

 

FINALLY:

If anyone knows some better solutions or fixes.  DO TELL!

[ACTIONpack]

I thought LESS is a preprocessor of CSS?

[snaphat (Myles Landwehr) Member]

I thought less was the 'opposite of more':

Less  is  a program similar to more (1), but it has many more features.  Less does not have to read the entire input file before starting, so with large input files it starts up faster than text editors like vi (1).  Less uses termcap (or terminfo on some systems), so  it  can run  on  a  variety  of  terminals.  There is even limited support for hardcopy terminals.  (On a hardcopy terminal, lines which should be printed at the top of the screen are prefixed with a caret.)

Commands are based on both more and vi.  Commands may be preceded by a decimal number, called N in the descriptions below.  The number  is used by some commands, as indicated.

[Lingwo]

I thought LESS is a preprocessor of CSS?

 

It is more than that.

Simplest is that it can make CSS dynamic.

[game_over]

I thought LESS is a preprocessor of CSS?

 

Whats your point?

[Taritsyn]

Hello, Kalint!

Thanks for a great guide! But there is one problem: is not recommended to use the `CssMinify` and `JsMinify` classes together with a Bundle Transformer. I will not explain why it should not do, because I have written about this in the documentation. As most simple solution to this problem I recommend to install the BundleTransformer.MicrosoftAjax package.

[Kalint]

Hello, Kalint!

Thanks for a great guide! But there is one problem: is not recommended to use the `CssMinify` and `JsMinify` classes together with a Bundle Transformer. I will not explain why it should not do, because I have written about this in the documentation. As most simple solution to this problem I recommend to install the BundleTransformer.MicrosoftAjax package.

Hm... I will look into this!

[Chris969872]

Excellent post.  Saved me a ton of time.  Thanks.

 

Did you have a chance to look into Taritsyn's comment?