Asset Pipeline for concrete5

The purpose of this concrete5 add-on is to provide a proof of concept of an Asset Pipeline implementation for concrete5. This would help a lot of developers to properly handle their site's static assets.

The purpose of an Asset Pipeline is to have a general way for developers to include different static assets (CSS and JS) to their views and handle their preprocessing correctly. While the latest and greatest concrete5 already handles asset preprocessing, it is currently not implemented in a very general way. The CSS preprocessing language is tied into LESS and e.g. JavaScript cannot be written with the CoffeeScript syntax directly throug the tools provided by concrete5.

This package attempts to solve these problems by providing a general pipeline through which different types of assets can be preprocessed, combined and served to the client in an easy way. The asset preprocessing is handled by Assetic which allows developers to easily add their preferred preprocessors for the assets now and also in the future if and when new such preprocessing languages arise.

This is currently work in progress! More guidance and instructions are added once this becomes a fully working version.

How to install?

Make sure you have Composer installed. Really, do not proceed if you do not know what Composer is (check the link).
Download or clone this repository and extract it into the /packages folder of your concrete5 installation.
Rename the folder to asset_pipeline.
Open up your console and navigate to the package's directory you just renamed. Run composer install to install all the composer packages.
Open up your web browser and navigate to the Dashboard of the website. Install the add-on through the Extend view of the dashboard.

How to use?

In your theme's view files you have a new variable available named $assets. This is an instance of Concrete\Package\AssetPipeline\Src\Service\Assets and you can call any methods available in that class by calling them against this object in your theme's view files.

Note that you will need to include a file in from your base template file (such as default.php) because otherwise the $assets variable is not available. This is because of the way this variable is made available to the view. Usually, the parts where you need to call the $assets variable are separated into specific template element files, so this should not be a problem.

As an example, this does not work:

default.php:

<!DOCTYPE html>
<html>
<head>
    <!-- This will result in error -->
    <?php echo $assets->css(array('main.scss')) ?>
    <?php Loader::element('header_required') ?>
</head>
<body>
    <p>Page</p>
    <?php Loader::element('footer_required') ?>
</body>
</html>

Instead, this is how you can use the $assets variable properly:

default.php:

<?php $this->inc('elements/header.php') ?>
<p>Page</p>
<?php $this->inc('elements/footer.php') ?>

elements/header.php:

<!DOCTYPE html>
<html>
<head>
    <!-- This will work properly -->
    <?php echo $assets->css(array('main.scss')) ?>
    <?php Loader::element('header_required') ?>
</head>
<body>

elements/footer.php:

<?php Loader::element('footer_required') ?>
</body>
</html>

Example theme

Example theme that is built with the Asset Pipeline can be found from here.

Example of outputting a URL for preprocessed CSS files

Within your theme files you can use the following snippet:

<?php echo $assets->css(array(
    'main.less',
    'second.scss',
    'third.scss',
)) ?>

This will reference three CSS files (specified above) within your theme's css folder, preprocess them and combine them into a single CSS file that is downloaded by the client. You may have also noticed that in the file list above there are both, Less and SCSS, files. Other file types also may be added by providing the preprocessing filters for them. This package only comes with Less and SCSS preprocessing filters.

The output of this call would look something like this:

<link href="/application/files/cache/css/style-18282c71313a64df0dccceacdbb9e563.css" rel="stylesheet" type="text/css" media="all">

Example of outputting a URL for preprocessed JS files

Within your theme files you can use the following snippet:

<?php echo $assets->js(array(
    'site.js',
    'second.js',
    'third.js',
)) ?>

This will reference three JS files (specified above) within your theme's js folder, preprocess them and combine them into a single JS file that is downloaded by the client. In this example, we only define plain JS files but other formats, such as CoffeeScript could be also used for JS in case the proper filters are provided for the .coffee file extension. This package does not come with that filter built-in since there is currently no plain PHP implementation for that language and enabling that filter would require installing external components on the computer which might require some level of technical expertise.

The output of this call would look something like this:

<script type="text/javascript" src="/application/files/cache/js/script-dafa89aba8ca8b9a8ba6b8a89caae77e.js"></script>

Options to be passed to the asset helper

In the above examples the css() and js() methods are called against an instance of Concrete\Package\AssetPipeline\Src\Service\Assets which also allows passing an options array to both of these functions as the second parameter.

The options that you can currently pass to both of these methods are:

name - The name part of the output cache file where the final asset is compiled to. By default for css-files: style. By default for js-files: script. Please note that this does not affect the fingerprint part of the final asset's filename. To learn more about the asset fingerprints, please read the Asset fingerprints section of this document.

An example of passing the options array to the css() method follows below. The options can be passed exactly the same way to the js() method as well.

<?php echo $assets->css(array(
    'main.less',
    'second.scss',
    'third.scss',
), array(
    'name' => 'site-styles',
)) ?>

The output of this call would look something like this:

<link href="/application/files/cache/css/site-styles-18282c71313a64df0dccceacdbb9e563.css" rel="stylesheet" type="text/css" media="all">

Asset fingerprints digests

As you may have noticed above, the actual final cached asset file names consist of two separate parts:

The name part which is the first readable part of the file's name
The fingerprint digest part which is suffixed into the file name with a dash in front of it.

In the following example, the first part (1.) is emphasized by italics and the second part (2.) is emphasized with bold characters:

style-18282c71313a64df0dccceacdbb9e563.css

The reason for suffixing the file names with the digest fingerprint is that the visitor's browser would always be forced to load the latest and greatest version of the asset file. It is kind of the technical version number for the cached asset file. This fingerprint is tied into the contents of the asset file so it will always differ if the file contents have been changed. This assures that the latest version of the asset file gets always sent to the site visitors and they will not be using an older version of the file cached locally into their hard drives.

Technically the digest fingerprint is generated by passing the file to PHP's hash_file function. The used hashing alhorithm is md5.

Configuration options

Some options can be given through the site's 'application/config/app.php' configuration file for the specific filters. These options should go into the asset_filter_options configuration block within that file.

The following options may be currently defined in the application configuration file:

less.legacy_url_support (default false)- Defines whether the Less files should swap out the relative file paths in the CSS with the full paths that they represent in the file system. Default behavior traditionally in concrete5 but disabled by default in the Asset Pipeline. To learn why, please read the Relative paths within the CSS section of this document.
js.compress (default true) - Defines whether plain JS files should be minified or not. Enabled by default.
css.compress (default true) - Defines whether plain CSS files should be minified or not. Enabled by default.

An example of the actual configuration file might look like this:

<?php
// Within your 'application/config/app.php' configuration file
return array(
    // ... you may have other configuration variables here ...
    'asset_filter_options' => array(
        'less' => array(
            'legacy_url_support' => false, // does not change the default
        ),
        'js' => array(
            'compress' => true, // does not change the default
        ),
        'css' => array(
            'compress' => true, // does not change the default
        ),
    ),
    // ... and you may have other configuration variables also here ...
);

Interoperability with concrete5's own configuration options

There are some asset specific configuration options that you can currently set through the concrete5 dashboard at /dashboard/system/optimization/cache. Some of these also affect the functionality of the Asset Pipeline.

Theme CSS Cache - If enabled, the generated CSS cache file is only refreshed if it does not already exist. This means that the same way as traditionally, with this setting enabled, you will need to clear the site's cache in case the CSS files are changed. Suggested to be only used on production sites.
Compress LESS Output - If enabled, the preprocessed CSS will be compressed, no matter what the preprocessing language is. This option has the name LESS in it because concrete5 internally uses currently only the LESS preprocessing language. Disable this if you want to debug your CSS or find any specific sections of your preprocessed CSS more easily.
enable source maps in generated CSS files - If enabled, the Less filter will generate the source maps the same was as the internal processing engine in concrete5. Please note that this applies only to the Less filter and is not currently implemented in the SCSS filter!

Relative paths within the CSS

In the CSS you quite often need to reference static files from the file system, such as images, font files, etc. Traditionally in concrete5, the Less files within your theme's folder referenced the relative folders within the theme automatically by replacing all the paths with the relative paths automatically. However, we think this is a bad design decision as it limits the paths that can be referenced from the themes (or makes it really awkward to reference them, e.g. ../../../../../). Also, this might work differently with different filters and some filters might not even implement this feature.

Instead, the built-in filters within this package provide an alternative way of referencing the static assets within the CSS files. This is through custom functions that can be used within the CSS files. This is implemented for both filters, the Less filter and the SCSS filter that come with this package.

To reference the static assets in different sections of the system, the following functions are available within your CSS files (in both .less and .scss files):

.current-theme {
    /* Reference an image within the active theme for the current page */
    background-image: theme-asset-url('images/your-background-image.jpg');
    /* Becomes (the actual path depends on the location of the theme): */
    /* background-image: url(http://site.com/application/themes/active_theme/images/your-background-image.jpg); */
}
.other-theme {
    /* Reference an image within another theme */
    background-image: theme-asset-url('images/your-background-image.jpg', 'theme_handle');
    /* Becomes (the actual path depends on the location of the theme): */
    /* background-image: url(http://site.com/application/themes/theme_handle/images/your-background-image.jpg); */
}
.application {
    /* Reference an image within the application folder */
   background-image: asset-url('images/your-background-image.jpg');
    /* Becomes: */
    /* background-image: url(http://site.com/application/images/your-background-image.jpg); */
}
.core {
    /* Reference an image within the core (concrete) folder */
   background-image: core-asset-url('images/your-background-image.jpg');
    /* Becomes: */
    /* background-image: url(http://site.com/concrete/images/your-background-image.jpg); */
}
.package {
    /* Reference an image within a package folder */
   background-image: package-asset-url('images/your-background-image.jpg', 'package_handle');
    /* Becomes: */
    /* background-image: url(http://site.com/packages/package_handle/images/your-background-image.jpg); */
}

In case you somewhere need only the paths of the assets, you can swap the -url suffix with -path in the function names to skip printing out the url() part of the resulting string.

Enabling the relative path replacing in CSS

If you are using the assets pipeline with any existing concrete5 themes, they might be also relying on the concrete5's internal functionality that it automatically swaps out all the relative URLs within the Less files. If you want to enable this feature with the assets pipeline, you can set the following configuration variable in your application/config/app.php:

<?php
// Within your 'application/config/app.php' configuration file
return array(
    // ... you may have other configuration variables here ...
    'asset_filter_options' => array(
        'less' => array(
            'legacy_url_support' => true
        ),
    ),
    // ... and you may have other configuration variables also here ...
);

Filters

Currently this package provides the followign filters:

SCSS preprocessing for CSS through leafo/scssphp. Applies to all the files with the .scss extension.
Less preprocessing for CSS through oyejorge/less.php. Applies to all the files with the .less extension.
Plain CSS file minification through natxet/CssMin. Applies for all the files with the .css extension.
JavaScript minification for JS through tedivm/jshrink. Applies for all the files with the .js extension.

New filters (e.g. for CoffeeScript) can be added through configuration. For adding new filters, please read the Adding new filters section of this document.

Adding new filters

New filters may be easily added for this package.

For adding a new filter, you can take a look at the Concrete\Package\AssetPipeline\Src\FilterProvider class which registers and builds the currently available built-in filters. All filters need to implement the Assetic\Filter\FilterInterface or one of its extensions in order to work properly with Assetic which handles the file output filtering.

For any filter related issues or guidance, you can refer to the Assetic's documentation.

The closure callbacks for the IoC container with the filter's associated key (such as assets/filter/less) will get the $assets variable as the second argument which is an instance of Concrete\Package\AssetPipeline\Src\Service\Assets. This object can provide more information about the asset compilation which may be required when initiating the filter. For example, you can get the theme customization's active variables by calling $assets->getStyleSheetVariables(). For an example, please see the existing closure callback implementations within the Concrete\Package\AssetPipeline\Src\FilterProvider class.

In addition, you will also need to tell the system that the new filters exist in order for them to be available for actual use. You can do this either by calling setting the filters directly to the Concrete\Package\AssetPipeline\Src\Asset\Manager class or alternatively by editing the the app.asset_filters configuration variable.

For an example on how to call the Asset\Manager directly, take a look at the FilterProvider's method named setFilters() and how it defines the available filters for the manager.

For directly editing the app.asset_filters configuration variable, you can use your application/config/app.php configuration file. The following example configuration can be used in that file for instance. The provided example sets the exact same filters as the default configurations provide:

<?php
// Within your 'application/config/app.php' configuration file
return array(
    // ... you may have other configuration variables here ...
    'asset_filters' => array(
        'less' => array(
            'applyTo' => '\.less$',
            'customizableStyles' => true,
        ),
        'scss' => array(
            'applyTo' => '\.scss$',
            'customizableStyles' => true,
        ),
        'jshrink' => array(
            'applyTo' => '\.js$',
        ),
        'cssmin' => array(
            'applyTo' => '\.css$',
        ),
    ),
    // ... and you may have other configuration variables also here ...
);

The configuration option values you can give to each filter in the filters configuration array are the following:

applyTo - A string that defines a regular expression which is used to match against the file paths of the files to be filtered. If the regular expression matches with the file path, the filter with the defined key will be searched from the IoC container (assets/filter/**key**) and applied to the matching file.
customizableStyles - A boolean that defines whether the filter can provide customizable styles or not to be used with concrete5 themes. In case this configuration variable is set to true, also a value extractor needs to be defined for the IoC container with the filter's key (assets/value/extractor/**key**) in order for the values to be extractable from the defined file type inside the theme's css/presets folder. For an example on implementing a value extractor, please take a look at the existing implementations within the src/StyleCustomizer/Style/Value/Extractor folder within this package.

Few notes

This package needs to override a couple of the core components to make this abstraction layer fully compatible with all the concrete5's internal components. Mostly, this means making the style/theme customization compatible with this layer and adding the possibility to have the style customization preset definitions in any possible CSS preprocessing syntax.

These overrides are automatically applied to the concrete5 installation upon the installation of this package and therefore do not require any additional installation steps from the user. They are provided by registering a special autoloader that overrides the specific class locations for the core to load them from. Technically they are also separated into their own folder (src/Core) in order to make it easier to understand for developers.

License

Licensed under the MIT license. See LICENSE for more information.

Name		Name	Last commit message	Last commit date
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src		src
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
composer.json		composer.json
composer.lock		composer.lock
controller.php		controller.php

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Asset Pipeline for concrete5

How to install?

How to use?

Example theme

Example of outputting a URL for preprocessed CSS files

Example of outputting a URL for preprocessed JS files

Options to be passed to the asset helper

Asset fingerprints digests

Configuration options

Interoperability with concrete5's own configuration options

Relative paths within the CSS

Enabling the relative path replacing in CSS

Filters

Adding new filters

Few notes

License

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peruskallio/c5_asset_pipeline

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Asset Pipeline for concrete5

How to install?

How to use?

Example theme

Example of outputting a URL for preprocessed CSS files

Example of outputting a URL for preprocessed JS files

Options to be passed to the asset helper

Asset fingerprints digests

Configuration options

Interoperability with concrete5's own configuration options

Relative paths within the CSS

Enabling the relative path replacing in CSS

Filters

Adding new filters

Few notes

License

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