docs/upgrade-3-to-4.md
Version 4 represents a major rewrite of Middleman-Sprockets to maintain support for Middleman 4+ & gain support of Sprockets 3+. With this come a lot of changes, some you'll make in your code and others in your expectations.
## Activation
The biggest change to start with is the removal of auto-activation. Since some configuration options have been added, this makes configuring them follow the norm for other extensions. To activate, in your `config.rb`:
```ruby
activate :sprockets
```
After activation you can still access the sprockets environment to append paths
```ruby
activate :sprockets
sprockets.append_path File.join(root, 'bower_components')
```
## Importing Assets
For adding assets from a gem or bower you may have been used to using `sprockets.import_asset ASSET_PATH` and having it added to the sitemap based on it's type. The process for this is considerably different now.
First, the `#import_asset` method has been removed, instead you should add a [link directive](https://github.com/rails/sprockets#the-link-directive) to reference the file you want imported. To follow along with the rails convension and import files that aren't necessarily linked from other assets -- add a manifest file. For example lets say we want to import fonts from [Font-Awesome](https://github.com/FortAwesome/Font-Awesome).
Assuming Font-Awesome has been installed with bower:
```ruby
# config.rb
activate :sprockets
sprockets.append_path File.join(root, 'bower_components')
```
```javascript
// source/javascripts/manifest.js
//
//= link font-awesome-webfont.eot
//= link font-awesome-webfont.svg
//= link font-awesome-webfont.ttf
//= link font-awesome-webfont.wof
//= link font-awesome-webfont.wof2
```
This will import the fonts into the sitemap under the configured `imported_asset_path`. So on build it would look like:
```
build/
+-- assets/
+-- font-awesome-webfont.eot
+-- font-awesome-webfont.svg
+-- font-awesome-webfont.ttf
+-- font-awesome-webfont.wof
+-- font-awesome-webfont.wof2
```
You may have noticed that second difference from 3.x -- the fonts weren't placed into `:font_dir`. Instead of trying to determine file type & using that path -- with 4.x all imported assets are placed under the `imported_asset_path`.
This path defaults to `assets` and is configurable:
```ruby
# config.rb
activate :sprockets do |c|
c.imported_asset_path = 'imported'
end
sprockets.append_path File.join(root, 'bower_components')
```
```javascripts
// source/javascripts/manifest.js
//
//= link font-awesome-webfont.eot
```
```
build/
+-- imported/
+-- font-awesome-webfont.eot
```
In addition to importing assets through link directives, assets can also be linked via any of the path helper methods. Again, looking at font-awesome instead of using a manifest file -- lets link it directly from our css that will use it:
```css
/* source/stylesheets/fonts.css.scss */
@font-face {
font-family: "Font Awesome";
src: font-url('font-awesome-webfont.eot');
}
```
```
build/
+-- assets/
+-- font-awesome-webfont.eot
```
Check out the [feature test](../features/linked_assets.feature) for more specifics.
## Middleman Helpers
Helpers are no longer included in the sprockets rendering context by default. To expose them, configure `expose_middleman_helpers` to true:
```ruby
# config.rb
activate :sprockets do |c|
c.expose_middleman_helpers = true
end
```
## Less Support
With 3.x Sprockets has [dropped support for Less](https://github.com/sstephenson/sprockets/pull/547), so be aware that your `.less` files are handled by Middleman directly. As a concequence, sprockets directives or importing of assets won't work.
> Run into an issue or think something is missing? [Let us know](https://github.com/middleman/middleman-sprockets/issues/new) or submit a pull request to help us improve.