Documentation & API reference
function rdf_preprocess_node
Implements hook_preprocess_HOOK() for node.html.twig.
File
- drupal/
core/ modules/ rdf/ rdf.module, line 497 - Enables semantically enriched output for Drupal sites in the form of RDFa.
Code
function rdf_preprocess_node(&$variables) {
// Adds RDFa markup to the node container. The about attribute specifies the
// URI of the resource described within the HTML element, while the @typeof
// attribute indicates its RDF type (e.g., foaf:Document, sioc:Person, and so
// on.)
$variables['attributes']['about'] = empty($variables['node_url']) ? NULL : $variables['node_url'];
$variables['attributes']['typeof'] = empty($variables['node']->rdf_mapping['rdftype']) ? NULL : $variables['node']->rdf_mapping['rdftype'];
// Adds RDFa markup to the title of the node. Because the RDFa markup is
// added to the <h2> tag which might contain HTML code, we specify an empty
// datatype to ensure the value of the title read by the RDFa parsers is a
// literal.
$variables['title_attributes']['property'] = empty($variables['node']->rdf_mapping['title']['predicates']) ? NULL : $variables['node']->rdf_mapping['title']['predicates'];
$variables['title_attributes']['datatype'] = '';
// In full node mode, the title is not displayed by node.html.twig so it is
// added in the <head> tag of the HTML page.
if ($variables['page']) {
$element = array(
'#tag' => 'meta',
'#attributes' => array(
'content' => $variables['label'],
'about' => $variables['node_url'],
),
);
if (!empty($variables['node']->rdf_mapping['title']['predicates'])) {
$element['#attributes']['property'] = $variables['node']->rdf_mapping['title']['predicates'];
}
drupal_add_html_head($element, 'rdf_node_title');
}
// Adds RDFa markup for the date.
if (!empty($variables['node']->rdf_mapping['created'])) {
$date_attributes = rdf_rdfa_attributes($variables['node']->rdf_mapping['created'], $variables['node']->created);
$variables['rdf_template_variable_attributes']['date'] = $date_attributes;
if ($variables['submitted']) {
$variables['rdf_template_variable_attributes']['submitted'] = $date_attributes;
}
}
// Adds RDFa markup for the relation between the node and its author.
if (!empty($variables['node']->rdf_mapping['uid'])) {
$variables['rdf_template_variable_attributes']['name']['rel'] = $variables['node']->rdf_mapping['uid']['predicates'];
if ($variables['submitted']) {
$variables['rdf_template_variable_attributes']['submitted']['rel'] = $variables['node']->rdf_mapping['uid']['predicates'];
}
}
// Adds RDFa markup annotating the number of comments a node has.
if (isset($variables['node']->comment_count) && !empty($variables['node']->rdf_mapping['comment_count']['predicates'])) {
// Annotates the 'x comments' link in teaser view.
if (isset($variables['content']['links']['comment']['#links']['comment-comments'])) {
$comment_count_attributes['property'] = $variables['node']->rdf_mapping['comment_count']['predicates'];
$comment_count_attributes['content'] = $variables['node']->comment_count;
$comment_count_attributes['datatype'] = $variables['node']->rdf_mapping['comment_count']['datatype'];
// According to RDFa parsing rule number 4, a new subject URI is created
// from the href attribute if no rel/rev attribute is present. To get the
// original node URL from the about attribute of the parent container we
// set an empty rel attribute which triggers rule number 5. See
// http://www.w3.org/TR/rdfa-syntax/#sec_5.5.
$comment_count_attributes['rel'] = '';
$variables['content']['links']['comment']['#links']['comment-comments']['attributes'] += $comment_count_attributes;
}
// In full node view, the number of comments is not displayed by
// node.html.twig so it is expressed in RDFa in the <head> tag of the HTML
// page.
if ($variables['page'] && user_access('access comments')) {
$element = array(
'#tag' => 'meta',
'#attributes' => array(
'about' => $variables['node_url'],
'property' => $variables['node']->rdf_mapping['comment_count']['predicates'],
'content' => $variables['node']->comment_count,
'datatype' => $variables['node']->rdf_mapping['comment_count']['datatype'],
),
);
drupal_add_html_head($element, 'rdf_node_comment_count');
}
}
}