DotLessBuildTasksDotNet

Use less.js-windows to automatically compile .less files to .css.

Installing DotLessBuildTasksDotNet

Use NuGet to install the DotLessBuildTasksDotNet package. NuGet 2.5 and later will add the necessary <Import ... element to your project file.

If your project is loaded before the DotLessBuildTasksDotNet.targets file is available (i.e. the first time the package is installed or package restore hasn't run yet) you'll need to reload the project for it to be imported.

NuGet's support for adding MSBuild targets is somewhat nascent. If you're building your project in an environment where you can't reload the project (e.g. continuous integration server) you'll probably want to use nuget restore as documented here.

Using DotLessBuildTasksDotNet

DotLessBuildTasksDotNet adds a custom build action to your project - CompileLessFile.

CompileLessFile is used to indicate that a .less file should be compiled into a .css file.

A corollary of this is that dotless is not run on every single .less file in your project - you need to specify which .less files to compile. This prevents redundant compilation of shared files like variables.less.

DotLessBuildTasksDotNet will run before your project builds and compile each .less file into a .css file. They are not automatically added to your project, you'll need to do that yourself.

Miscellaney

If you're using a source control system then consider ignoring the output files.

If you're using Git and can isolate the output files to one directory (e.g. MyProject\Less) then you can quickly ignore all .css files by creating a .gitignore file in that directory with the following contents:

*.css