diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 03dc12192d35df6707cc02eefe4a615a0148b792..b84302918545ca104acd116e1d27c17643f5c0c6 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -372,6 +372,15 @@ function _theme($hook, $variables = array()) {
$preprocessor_function($variables, $hook, $info);
}
}
+ // Allow theme preprocess functions to set $variables['#attached'] and use
+ // it like the #attached property on render arrays. In Drupal 8, this is the
+ // (only) officially supported method of attaching assets from preprocess
+ // functions. Assets attached here should be associated with the template
+ // that we're preprocessing variables for.
+ if (isset($variables['#attached'])) {
+ $preprocess_attached = ['#attached' => $variables['#attached']];
+ drupal_render($preprocess_attached, TRUE);
+ }
}
// Generate the output using either a function or a template.
@@ -1946,15 +1955,8 @@ function template_preprocess_maintenance_page(&$variables) {
$attributes['class'] = $classes;
// @see system_page_build()
- $attached = array(
- '#attached' => array(
- 'library' => array(
- 'core/normalize',
- 'system/maintenance',
- ),
- ),
- );
- drupal_render($attached);
+ $variables['#attached']['library'][] = 'core/normalize';
+ $variables['#attached']['library'][] = 'system/maintenance';
}
/**
diff --git a/core/modules/system/src/Tests/Common/RenderTest.php b/core/modules/system/src/Tests/Common/RenderTest.php
index d07085cf2cfb4e44ef855c76cee07a3c6e069c85..6c286cab01630b7017394a9317bed80db12ef08c 100644
--- a/core/modules/system/src/Tests/Common/RenderTest.php
+++ b/core/modules/system/src/Tests/Common/RenderTest.php
@@ -410,6 +410,31 @@ function testDrupalRenderThemeArguments() {
$this->assertEqual(drupal_render($element), $element['#foo'] . $element['#bar'], 'Passing arguments to theme functions works');
}
+ /**
+ * Tests theme preprocess functions being able to attach assets.
+ */
+ function testDrupalRenderThemePreprocessAttached() {
+ \Drupal::state()->set('theme_preprocess_attached_test', TRUE);
+
+ $test_element = [
+ '#theme' => 'common_test_render_element',
+ 'foo' => [
+ '#markup' => 'Kittens!',
+ ],
+ ];
+ drupal_render($test_element);
+
+ $expected_attached = [
+ 'library' => [
+ 'test/generic_preprocess',
+ 'test/specific_preprocess',
+ ]
+ ];
+ $this->assertEqual($expected_attached, $test_element['#attached'], 'All expected assets from theme preprocess hooks attached.');
+
+ \Drupal::state()->set('theme_preprocess_attached_test', FALSE);
+ }
+
/**
* Tests caching of an empty render item.
*/
diff --git a/core/modules/system/tests/modules/common_test/common_test.module b/core/modules/system/tests/modules/common_test/common_test.module
index e23a842eedba2fb1d60ab2d9a94dd731cd4449fa..e812b617d6df71f5362e171bd0f9a102a24edd84 100644
--- a/core/modules/system/tests/modules/common_test/common_test.module
+++ b/core/modules/system/tests/modules/common_test/common_test.module
@@ -142,6 +142,30 @@ function theme_common_test_empty($variables) {
return '';
}
+/**
+ * Implements MODULE_preprocess().
+ *
+ * @see RenderTest::testDrupalRenderThemePreprocessAttached()
+ */
+function common_test_preprocess(&$variables, $hook) {
+ if (!\Drupal::state()->get('theme_preprocess_attached_test', FALSE)) {
+ return;
+ }
+ $variables['#attached']['library'][] = 'test/generic_preprocess';
+}
+
+/**
+ * Implements MODULE_preprocess_HOOK().
+ *
+ * @see RenderTest::testDrupalRenderThemePreprocessAttached()
+ */
+function common_test_preprocess_common_test_render_element(&$variables) {
+ if (!\Drupal::state()->get('theme_preprocess_attached_test', FALSE)) {
+ return;
+ }
+ $variables['#attached']['library'][] = 'test/specific_preprocess';
+}
+
/**
* Implements hook_library_info_alter().
*/
diff --git a/core/modules/system/theme.api.php b/core/modules/system/theme.api.php
index 1a613b7d6f750c38a16728db5d701554b3524fec..26c998aab64e79ad1577508697176f3e582decf2 100644
--- a/core/modules/system/theme.api.php
+++ b/core/modules/system/theme.api.php
@@ -159,6 +159,21 @@
* suggestions as input, and can change this array (adding suggestions and
* removing them).
*
+ * @section Assets
+ *
+ * We can distinguish between two types of assets:
+ * 1. global assets (loaded on all pages where the theme is in use): these are
+ * defined in the theme's *.info.yml file.
+ * 2. template-specific assets (loaded on all pages where a specific template is
+ * in use): these can be added by in preprocessing functions, using @code
+ * $variables['#attached'] @endcode, e.g.:
+ * @code
+ * function seven_preprocess_menu_local_action(array &$variables) {
+ * // We require Modernizr's touch test for button styling.
+ * $variables['#attached']['library'][] = 'core/modernizr';
+ * }
+ * @endcode
+ *
* @see hooks
* @see callbacks
* @see theme_render
diff --git a/core/modules/views/views.module b/core/modules/views/views.module
index f3877e03c0ef501bb3227863b96d23115965d997..a41e73e182b5abe5fea23e8130da73cde255dc80 100644
--- a/core/modules/views/views.module
+++ b/core/modules/views/views.module
@@ -329,8 +329,7 @@ function views_preprocess_page(&$variables) {
unset($class[$key]);
$attributes['class'] = $class;
$attributes['data-views-page-contextual-id'] = $variables['title_suffix']['contextual_links']['#id'];
- $attached['#attached']['library'][] = 'views/views.contextual-links';
- drupal_render($attached);
+ $variables['#attached']['library'][] = 'views/views.contextual-links';
}
}
}
diff --git a/core/themes/bartik/bartik.theme b/core/themes/bartik/bartik.theme
index db027bea9ba3fb9ed7fba1051b260c4ddaaf0e69..60f9a34d8c4d6cb477fa88b71a5457cce7904219 100644
--- a/core/themes/bartik/bartik.theme
+++ b/core/themes/bartik/bartik.theme
@@ -87,16 +87,9 @@ function bartik_preprocess_maintenance_page(&$variables) {
if (!$variables['db_is_active']) {
$variables['site_name'] = '';
}
- // Normally we could attach libraries via hook_page_alter(), but when the
- // database is inactive it's not called so we add them here.
- $libraries = array(
- '#attached' => array(
- 'library' => array(
- 'bartik/maintenance_page',
- ),
- ),
- );
- drupal_render($libraries);
+
+ // Bartik has custom styling for the maintenance page.
+ $variables['#attached']['library'][] = 'bartik/maintenance_page';
// Set the options that apply to both page and maintenance page.
_bartik_process_page($variables);
diff --git a/core/themes/seven/seven.libraries.yml b/core/themes/seven/seven.libraries.yml
index d7a9495d0b79b753978fafcee0e4b7cd1ce435a0..a79487161cdf7d6f7d94a144242028b99704c3af 100644
--- a/core/themes/seven/seven.libraries.yml
+++ b/core/themes/seven/seven.libraries.yml
@@ -16,7 +16,7 @@ install-page:
theme:
css/theme/install-page.css: {}
dependencies:
- - system/maintenance
+ - seven/maintenance-page
drupal.nav-tabs:
version: VERSION
diff --git a/core/themes/seven/seven.theme b/core/themes/seven/seven.theme
index ccd1c92bc1f4f47785d1c7189f5ecebe24f60d73..88c25704bbbfcccc8b15a3a82067e4bd75319228 100644
--- a/core/themes/seven/seven.theme
+++ b/core/themes/seven/seven.theme
@@ -128,14 +128,7 @@ function seven_preprocess_menu_local_action(array &$variables) {
$variables['link']['#options']['attributes']['class'][] = 'button--small';
// We require Modernizr's touch test for button styling.
- $libraries = array(
- '#attached' => array(
- 'library' => array(
- 'core/modernizr',
- ),
- ),
- );
- drupal_render($libraries);
+ $variables['#attached']['library'][] = 'core/modernizr';
}
/**
@@ -158,17 +151,8 @@ function seven_preprocess_install_page(&$variables) {
$classes[] = 'install-background';
$attributes['class'] = $classes;
- // Normally we could attach libraries via hook_page_alter(), but when the
- // database is inactive it's not called so we add them here.
- $libraries = array(
- '#attached' => array(
- 'library' => array(
- 'seven/maintenance-page',
- 'seven/install-page',
- ),
- ),
- );
- drupal_render($libraries);
+ // Seven has custom styling for the install page.
+ $variables['#attached']['library'][] = 'seven/install-page';
}
/**
@@ -181,16 +165,8 @@ function seven_preprocess_maintenance_page(&$variables) {
$classes[] = 'maintenance-background';
$attributes['class'] = $classes;
- // // Normally we could attach libraries via hook_page_alter(), but when the
- // // database is inactive it's not called so we add them here.
- $libraries = array(
- '#attached' => array(
- 'library' => array(
- 'seven/maintenance-page',
- ),
- ),
- );
- drupal_render($libraries);
+ // Seven has custom styling for the maintenance page.
+ $variables['#attached']['library'][] = 'seven/maintenance-page';
}
/**