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<?php
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// $Id: rdf.feedapi.inc,v 1.3 2009/02/22 20:44:14 arto Exp $
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//////////////////////////////////////////////////////////////////////////////
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// Feed Element Mapper API hooks
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/**
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* Implementation of hook_feedapi_mapper().
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*
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* @requires feedapi_mapper >= 6.x-1.0-beta9
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*/
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function rdf_feedapi_mapper($op, $node, $feed_element = array(), $field_name = '', $sub_field = '') {
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switch ($op) {
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case 'describe':
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return t('Maps feed item properties into RDF repositories and into CCK fields as defined by RDF schema settings');
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case 'list':
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// The sub-fields define the actual mapping targets available in the
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// Feed Element Mapper drop-down boxes for each feed item property.
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// In our case, we expose all mutable RDF repositories as targets, and
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// additionally include a 'System' target that will perform a reverse
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// mapping through the RDF Schema API:
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$sub_fields = array('system' => t('System'));
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foreach (rdf_get_repositories() as $repo_name => $repo_info) {
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if (!empty($repo_info['enabled']) && !empty($repo_info['mutable'])) {
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$sub_fields[$repo_name] = $repo_info['title'];
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}
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}
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return array('rdf' => $sub_fields); // $node->rdf is defined in rdf_nodeapi('prepare')
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case 'map':
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// NOTE: $node->nid is unset at this point if the feed item node is being created.
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// We're unable to map individual feed item properties, as the
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// hook_feedapi_mapper() API misplaces the information on what the
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// feed item property's name is (i.e. it only passes in the value, in
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// $feed_element, not the name), without which we are powerless to do
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// any RDF-related mapping. However, we do support collections of feed
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// item properties, such as the 'rdf' collection exported by the
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// patched version (see drupal.org issue #XXXXXX) of the Common
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// Syndication Parser for RSS 1.0, as collections of properties are
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// indexed by the property name and hence allow us to obtain the
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// predicate in question. This is still a bit iffy, however, in the
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// sense that the property collections are actually indexed by
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// namespaced QNames/CURIEs, so namespace prefixes become quite (and
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// unduly) significant as we don't have any other means of determining
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// the full predicate URI. Provided that well-known "standard"
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// prefixes are used in the feed and on the site running this code,
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// all will be well.
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if (is_array($feed_element)) { // is a collection of properties
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$namespaces = rdf_get_namespaces();
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$data = array();
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// Add a statement indicating where the feed item node originates from:
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if (isset($feed_element['rdf_about'][0])) {
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$data['dc:origin'][] = rdf_uri($feed_element['rdf_about'][0]);
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unset($feed_element['rdf_about']);
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}
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// Process all RDF statements extracted from the feed item:
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foreach ($feed_element as $predicate => $values) {
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$predicate = implode(':', explode('_', $predicate, 2)); // first '_' => ':'
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$namespace = substr($predicate, 0, strpos($predicate, ':'));
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if (isset($namespaces[$namespace])) { // skip any unknown namespaces
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foreach (is_array($values) ? $values : array($values) as $value) {
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$data[$predicate][] = rdf_str_to_val($value); // attempt to cast untyped values
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}
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}
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}
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if ($sub_field == 'system') {
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// Attempt reverse CCK field mappings using the RDF Schema module:
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_rdf_feedapi_mapper_cck($node, $data);
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}
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else {
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// Store the extracted RDF statements in the RDF repository
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// selected as the target for the mapping (the repository name is
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// passed in $sub_field). We have to do this in an indirect manner
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// as (for new feed item nodes) the $node object is still being
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// constructed and therefore doesn't have a $node->nid, and hence
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// of course doesn't have a URI either. See rdf_nodeapi('prepare')
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// and rdf_nodeapi('insert') for details on how the $node->rdf and
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// $node->rdf_options mechanisms work.
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$node->rdf_options = array('repository' => $sub_field);
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$node->rdf = $data;
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}
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}
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return $node;
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}
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return FALSE;
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}
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/**
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* @see rdf_feedapi_mapper()
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* @private
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*/
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function _rdf_feedapi_mapper_cck(&$node, $data) {
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// TODO: all this probably should go into the RDF Schema module proper.
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static $var_prefix = 'rdf_schema_property_content_';
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foreach ($data as $predicate => $values) {
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// Ensure the QName/CURIE property names can be mapped into valid
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// predicate URIs, and ruthlessly skip any that can't. See the note in
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// rdf_feedapi_mapper() regarding the undue importance we must place on
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// namespace prefixes for all this to work.
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if (($predicate = rdf_qname_to_uri($predicate)) && rdf_is_valid_uri($predicate)) {
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// Check if any RDF Schema-based CCK field mappings have been defined
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// for this particular predicate URI:
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$result = db_query('SELECT * FROM {variable} WHERE name LIKE "%s%%" AND value = "%s"', $var_prefix, serialize($predicate));
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while ($row = db_fetch_object($result)) {
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// For each defined CCK field mapping, graft the property values
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// onto the $node object in a CCK-compatible manner. The idea is
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// that CCK will take care of actually storing these values once
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// hook_nodeapi('insert') or hook_nodeapi('update') gets called.
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$field_name = substr($row->name, strlen($var_prefix));
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foreach ($values as $value) {
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$field = isset($node->$field_name) ? $node->$field_name : array();
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$field[] = array('value' => rdf_val_to_str($value));
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$node->$field_name = $field;
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}
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}
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}
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}
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return $node;
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}
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