modules/relations/relations.module

<?php
// $Id$

//////////////////////////////////////////////////////////////////////////////
// Module settings

define('RELATIONS_REPOSITORY', 'relations');
define('RELATIONS_PREDICATE',  'http://www.w3.org/2000/01/rdf-schema#seeAlso');

//////////////////////////////////////////////////////////////////////////////
// Core API hooks

/**
 * Implementation of hook_help().
 */
function relations_help($path, $arg = NULL) {
  switch ($path) {
    case 'node/%/relations#table':
      return '<p>' . t('To create a new relationship, type in the title or URL of another content item in the textbox above. You must have editor privileges for either the source or target item, and at least reader privileges for the other item.') . '</p>';
  }
}

/**
 * Implementation of hook_perm().
 */
function relations_perm() {
  return array(
    'view node relations',
    'create node relations',
    'delete node relations',
  );
}

/**
 * Implementation of hook_menu().
 */
function relations_menu() {
  return array(
    'node/%node/relations' => array(
      'title' => 'Relations',
      'description' => 'List, edit, or create node relationships.',
      'type' => MENU_LOCAL_TASK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(1, 'view node relations', TRUE),
      'page callback' => 'drupal_get_form',
      'page arguments' => array('relations_node_form', 1),
      'file' => 'relations.pages.inc',
      'weight' => 3,
    ),
    'node/%node/relations/autocomplete' => array(
      'title' => 'Relations autocomplete',
      'type' => MENU_CALLBACK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(1, 'create node relations', TRUE),
      'page callback' => 'relations_node_title_autocomplete',
      'page arguments' => array(1),
      'file' => 'relations.pages.inc',
    ),
    'node/%node/relations/delete/%node' => array(
      'title' => 'Delete relation',
      'type' => MENU_CALLBACK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(1, 'delete node relations', TRUE),
      'page callback' => 'drupal_get_form',
      'page arguments' => array('relations_node_delete', 1, 4),
      'file' => 'relations.pages.inc',
    ),

    // AHAH handlers for unsaved nodes
    'node/add/relations/autocomplete' => array(
      'title' => 'Relations autocomplete (for unsaved nodes)',
      'type' => MENU_CALLBACK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(NULL, 'view node relations', TRUE),
      'page callback' => 'relations_node_title_autocomplete',
      'page arguments' => array(NULL),
      'file' => 'relations.pages.inc',
    ),
    'node/add/relations/create' => array(
      'title' => 'Add relation (for unsaved nodes)',
      'type' => MENU_CALLBACK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(NULL, 'view node relations', TRUE),
      'page callback' => 'relations_node_session_create',
      'page arguments' => array(),
      'file' => 'relations.pages.inc',
    ),
    'node/add/relations/delete/%node' => array(
      'title' => 'Delete relation (for unsaved nodes)',
      'type' => MENU_CALLBACK,
      'access callback' => 'relations_menu_access',
      'access arguments' => array(NULL, 'view node relations', TRUE),
      'page callback' => 'relations_node_session_delete',
      'page arguments' => array(4),
      'file' => 'relations.pages.inc',
    ),

    // Administer >> Site configuration >> RDF settings >> Relations
    'admin/settings/rdf/relations' => array(
      'title' => 'Relations',
      'description' => 'Settings for the Relations API module.',
      'access arguments' => array('administer site configuration'),
      'page callback' => 'drupal_get_form',
      'page arguments' => array('relations_admin_settings'),
      'file' => 'relations.admin.inc',
    ),
  );
}

/**
 * Implementation of hook_menu_alter().
 */
function relations_menu_alter(&$items) {
  if (!variable_get('relations_ui_node_tab', '1')) {
    unset($items['node/%node/relations']);
  }
}

/**
 * Implementation of hook_block().
 */
function relations_block($op = 'list', $delta = 0, $edit = array()) {
  $node_types = node_get_types('names');

  switch ($op) {
    case 'list':
      $blocks = array(
        'relations' => array(
          'info'   => t('Relations'),
          'region' => 'right',
          'weight' => -3,
          'cache'  => BLOCK_CACHE_PER_PAGE | BLOCK_CACHE_PER_USER,
        ),
      );
      foreach (relations_get_node_types() as $node_type) {
        $blocks[$node_type] = array(
          'info'   => t('Relations: !type', array('!type' => $node_types[$node_type])),
          'region' => 'right',
          'weight' => -3,
          'cache'  => BLOCK_CACHE_PER_PAGE | BLOCK_CACHE_PER_USER,
        );
      }
      return $blocks;

    case 'view':
      $block = array();
      if (arg(0) == 'node' && is_numeric(arg(1)) && arg(2) != 'edit') {
        $node = node_load(arg(1));

        switch ($delta) {
          case 'relations':
            $block['subject'] = t('Related content');
            $block['content'] = theme('relations_node_block', $node);
            break;
          default:
            if (array_search($delta, relations_get_node_types($node)) && isset($node_types[$delta])) {
              $block['subject'] = t('Related content: !type', array('!type' => $node_types[$delta]));
              $block['content'] = theme('relations_node_block', $node, array('type' => $delta));
            }
            break;
        }
      }
      return $block;
  }
}

/**
 * Implementation of hook_forms().
 */
function relations_forms() {
  return array(
    'relations_node_form' => array(
      'callback' => 'relations_node_form',
    ),
  );
}

/**
 * Implementation of hook_theme()
 */
function relations_theme() {
  return array(
    'relations_node_form' => array(
      'arguments' => array('node' => NULL),
      'file' => 'relations.pages.inc',
    ),
    'relations_node_table' => array(
      'arguments' => array('node' => NULL),
      'file' => 'relations.pages.inc',
    ),
    'relations_node_block' => array(
      'arguments' => array('node' => NULL),
      'file' => 'relations.pages.inc',
    ),
    'relations_node_list' => array(
      'arguments' => array('nodes' => NULL),
      'file' => 'relations.pages.inc',
    ),
    'relations_admin_settings' => array(
      'arguments' => array('form' => NULL),
      'file' => 'relations.admin.inc',
    ),
  );
}

/**
 * Implementation of hook_form_alter().
 *
 * @see relations_nodeapi()
 */
function relations_form_alter(&$form, $form_state, $form_id) {
  if (isset($form['type']) && isset($form['#node'])) {
    $node = $form['#node'];

    if ($form['type']['#value'] .'_node_form' == $form_id && relations_is_node_type_enabled($node->type)) {
      if (!variable_get('relations_ui_node_edit', '1')) {
        return; // configured at <admin/settings/rdf/relations>
      }

      $form['relations'] = array(
        '#type'          => 'fieldset',
        '#access'        => user_access('create node relations'),
        '#title'         => t('Related content'),
        '#collapsible'   => TRUE,
        '#collapsed'     => TRUE,
        '#prefix'        => '<div class="relations">',
        '#suffix'        => '</div>',
        '#weight'        => 20,
      );
      $form['relations']['relations_blocks'] = array(
        '#type'          => 'checkboxes',
        '#title'         => t('Enabled related content types'),
        '#default_value' => relations_get_node_types($node),
        '#options'       => array_map('t', array_intersect_key(node_get_types('names'), relations_get_node_types())),
        '#description'   => t('Select which types of related content you wish to display when this node is viewed.'),
      );

      module_load_include('inc', 'relations', 'relations.pages');
      $form['relations']['relations_table'] = relations_node_form(array(), $node, TRUE);
    }
  }
}

/**
 * Implementation of hook_nodeapi().
 */
function relations_nodeapi(&$node, $op, $arg = 0) {
  if (relations_is_node_type_enabled($node->type)) {
    switch ($op) {
      case 'prepare':
        if (empty($_POST)) {
          $_SESSION['relations'] = array('create' => array(), 'delete' => array());
        }
        $node->relations_blocks = relations_get_node_types($node);
        break;
      case 'insert':
      case 'update':
        if (!empty($_SESSION['relations']['delete'])) {
          foreach ($_SESSION['relations']['delete'] as $nid => $title) {
            relations_api_delete($node->nid, $nid);
          }
        }
        if (!empty($_SESSION['relations']['create'])) {
          foreach ($_SESSION['relations']['create'] as $nid => $title) {
            relations_api_create($node->nid, $nid);
          }
        }
        unset($_SESSION['relations']);
        if (isset($node->relations_blocks)) {
          $node->relations_blocks = array_filter($node->relations_blocks, 'is_string');
          variable_set('relations_blocks_node_'. $node->nid, $node->relations_blocks);
        }
        break;
      case 'delete':
        variable_del('relations_blocks_node_'. $node->nid);
        break;
    }
  }
}

//////////////////////////////////////////////////////////////////////////////
// Picker API hooks

function relations_picker_access($node2) {
  // When adding relations to an existing node:
  if (!empty($_SERVER['HTTP_REFERER']) && preg_match('!node/(\d+)/!', $_SERVER['HTTP_REFERER'], $matches)) {
    $node1 = node_load((int)$matches[1]);
    return relations_allowed($node1, $node2);
  }
  // When adding relations to a node to be created:
  if (!empty($_SESSION['relations'])) {
    return relations_allowed(TRUE, $node2);
  }
}

//////////////////////////////////////////////////////////////////////////////
// Relations API implementation

function relations_menu_access($node, $perm) {
  return user_access($perm) && (empty($node) || relations_is_node_type_enabled($node->type));
}

function relations_is_node_type_enabled($type) {
  return array_search($type, relations_get_node_types());
}

function relations_get_node_types($node = NULL) {
  return isset($node->nid) ?
    variable_get('relations_blocks_node_'. $node->nid, relations_get_node_types(NULL)) :
    array_filter(variable_get('relations_node_types', array()), 'is_string');
}

function relations_get_predicate() {
  return variable_get('relations_predicate', RELATIONS_PREDICATE);
}

function relations_get_predicates($op = NULL) {
  switch ($op) {
    case 'keys':
      return array_combine(array_keys(relations_get_predicates()), array_fill(0, count(relations_get_predicates()), ''));
    default:
      return array(
        relations_get_predicate() => (object)array('title' => t('See also'), 'uri' => relations_get_predicate(), 'bidirectional' => TRUE),
      );
  }
}

function relations_rdf_options() {
  return array('repository' => RELATIONS_REPOSITORY);
}

function relations_node_url($nid) {
  return url('node/'. $nid, array('alias' => TRUE, 'absolute' => TRUE));
}

function relations_api_query($url) {
  // TODO: this breaks encapsulation; should probably implement multi-queries directly in RDF API.
  return array_merge(
    rdf_query(rdf_uri($url), NULL, NULL, relations_rdf_options())->to_array(),
    rdf_query(NULL, NULL, rdf_uri($url), relations_rdf_options())->to_array());
}

function relations_api_lookup($node, array $options = array()) {
  global $user;
  $account = empty($options['user']) ? $user : (is_object($options['user']) ? $options['user'] : user_load($options['user']));
  $nid = is_object($node) ? $node->nid : (int)$node;

  // Support for filtering related nodes by one or more content types:
  if (!empty($options['type'])) {
    $options['type'] = is_array($options['type']) ? $options['type'] : array($options['type']);
  }

  $nodes = array();
  $results = relations_api_query(relations_node_url($nid));
  foreach ($results as $triple) {
    list($s, $p, $o) = $triple;
    if ((preg_match('!node/'. $nid .'$!', (string)$s) && preg_match('!node/(\d+)$!', (string)$o, $matches)) ||
        (preg_match('!node/'. $nid .'$!', (string)$o) && preg_match('!node/(\d+)$!', (string)$s, $matches))) {
      if (($node = node_load($matches[1])) && node_access('view', $node, $account)) {
        if (empty($options['type']) || in_array($node->type, $options['type'])) {
          $nodes[$node->nid] = $node;
        }
      }
    }
  }
  return $nodes;
}

function relations_api_create($node1, $node2, array $options = array()) {
  $nid1 = is_object($node1) ? $node1->nid : (int)$node1;
  $nid2 = is_object($node2) ? $node2->nid : (int)$node2;

  // Make sure we never insert duplicate statements:
  if (($existing = relations_api_lookup($nid1, $options)) && isset($existing[$nid2])) {
    return TRUE;
  }

  $url1 = rdf_uri(relations_node_url($nid1));
  $url2 = rdf_uri(relations_node_url($nid2));
  return rdf_insert($url1, relations_get_predicate(), $url2, relations_rdf_options());
}

function relations_api_delete($node1, $node2, array $options = array()) {
  $nid1 = is_object($node1) ? $node1->nid : (int)$node1;
  $nid2 = is_object($node2) ? $node2->nid : (int)$node2;

  $url1 = rdf_uri(relations_node_url($nid1));
  $url2 = rdf_uri(relations_node_url($nid2));
  rdf_delete($url1, relations_get_predicate(), $url2, relations_rdf_options());
  rdf_delete($url2, relations_get_predicate(), $url1, relations_rdf_options());
  return TRUE;
}

function relations_allowed($node1, $node2) {
  // Must have edit access to either the source or destination node, and
  // view access to the target node (view access to the source node is
  // implied):
  $editor1 = is_object($node1) ? node_access('update', $node1) : (bool)$node1;  
  $editor2 = node_access('update', $node2);
  $reader2 = node_access('view', $node2);
  return ($editor1 || $editor2) && $reader2;
}
1	<?php
2	// $Id$
3
4	//////////////////////////////////////////////////////////////////////////////
5	// Module settings
6
7	define('RELATIONS_REPOSITORY', 'relations');
8	define('RELATIONS_PREDICATE', 'http://www.w3.org/2000/01/rdf-schema#seeAlso');
9
10	//////////////////////////////////////////////////////////////////////////////
11	// Core API hooks
12
13	/**
14	* Implementation of hook_help().
15	*/
16	function relations_help($path, $arg = NULL) {
17	switch ($path) {
18	case 'node/%/relations#table':
19	return '<p>' . t('To create a new relationship, type in the title or URL of another content item in the textbox above. You must have editor privileges for either the source or target item, and at least reader privileges for the other item.') . '</p>';
20	}
21	}
22
23	/**
24	* Implementation of hook_perm().
25	*/
26	function relations_perm() {
27	return array(
28	'view node relations',
29	'create node relations',
30	'delete node relations',
31	);
32	}
33
34	/**
35	* Implementation of hook_menu().
36	*/
37	function relations_menu() {
38	return array(
39	'node/%node/relations' => array(
40	'title' => 'Relations',
41	'description' => 'List, edit, or create node relationships.',
42	'type' => MENU_LOCAL_TASK,
43	'access callback' => 'relations_menu_access',
44	'access arguments' => array(1, 'view node relations', TRUE),
45	'page callback' => 'drupal_get_form',
46	'page arguments' => array('relations_node_form', 1),
47	'file' => 'relations.pages.inc',
48	'weight' => 3,
49	),
50	'node/%node/relations/autocomplete' => array(
51	'title' => 'Relations autocomplete',
52	'type' => MENU_CALLBACK,
53	'access callback' => 'relations_menu_access',
54	'access arguments' => array(1, 'create node relations', TRUE),
55	'page callback' => 'relations_node_title_autocomplete',
56	'page arguments' => array(1),
57	'file' => 'relations.pages.inc',
58	),
59	'node/%node/relations/delete/%node' => array(
60	'title' => 'Delete relation',
61	'type' => MENU_CALLBACK,
62	'access callback' => 'relations_menu_access',
63	'access arguments' => array(1, 'delete node relations', TRUE),
64	'page callback' => 'drupal_get_form',
65	'page arguments' => array('relations_node_delete', 1, 4),
66	'file' => 'relations.pages.inc',
67	),
68
69	// AHAH handlers for unsaved nodes
70	'node/add/relations/autocomplete' => array(
71	'title' => 'Relations autocomplete (for unsaved nodes)',
72	'type' => MENU_CALLBACK,
73	'access callback' => 'relations_menu_access',
74	'access arguments' => array(NULL, 'view node relations', TRUE),
75	'page callback' => 'relations_node_title_autocomplete',
76	'page arguments' => array(NULL),
77	'file' => 'relations.pages.inc',
78	),
79	'node/add/relations/create' => array(
80	'title' => 'Add relation (for unsaved nodes)',
81	'type' => MENU_CALLBACK,
82	'access callback' => 'relations_menu_access',
83	'access arguments' => array(NULL, 'view node relations', TRUE),
84	'page callback' => 'relations_node_session_create',
85	'page arguments' => array(),
86	'file' => 'relations.pages.inc',
87	),
88	'node/add/relations/delete/%node' => array(
89	'title' => 'Delete relation (for unsaved nodes)',
90	'type' => MENU_CALLBACK,
91	'access callback' => 'relations_menu_access',
92	'access arguments' => array(NULL, 'view node relations', TRUE),
93	'page callback' => 'relations_node_session_delete',
94	'page arguments' => array(4),
95	'file' => 'relations.pages.inc',
96	),
97
98	// Administer >> Site configuration >> RDF settings >> Relations
99	'admin/settings/rdf/relations' => array(
100	'title' => 'Relations',
101	'description' => 'Settings for the Relations API module.',
102	'access arguments' => array('administer site configuration'),
103	'page callback' => 'drupal_get_form',
104	'page arguments' => array('relations_admin_settings'),
105	'file' => 'relations.admin.inc',
106	),
107	);
108	}
109
110	/**
111	* Implementation of hook_menu_alter().
112	*/
113	function relations_menu_alter(&$items) {
114	if (!variable_get('relations_ui_node_tab', '1')) {
115	unset($items['node/%node/relations']);
116	}
117	}
118
119	/**
120	* Implementation of hook_block().
121	*/
122	function relations_block($op = 'list', $delta = 0, $edit = array()) {
123	$node_types = node_get_types('names');
124
125	switch ($op) {
126	case 'list':
127	$blocks = array(
128	'relations' => array(
129	'info' => t('Relations'),
130	'region' => 'right',
131	'weight' => -3,
132	'cache' => BLOCK_CACHE_PER_PAGE \| BLOCK_CACHE_PER_USER,
133	),
134	);
135	foreach (relations_get_node_types() as $node_type) {
136	$blocks[$node_type] = array(
137	'info' => t('Relations: !type', array('!type' => $node_types[$node_type])),
138	'region' => 'right',
139	'weight' => -3,
140	'cache' => BLOCK_CACHE_PER_PAGE \| BLOCK_CACHE_PER_USER,
141	);
142	}
143	return $blocks;
144
145	case 'view':
146	$block = array();
147	if (arg(0) == 'node' && is_numeric(arg(1)) && arg(2) != 'edit') {
148	$node = node_load(arg(1));
149
150	switch ($delta) {
151	case 'relations':
152	$block['subject'] = t('Related content');
153	$block['content'] = theme('relations_node_block', $node);
154	break;
155	default:
156	if (array_search($delta, relations_get_node_types($node)) && isset($node_types[$delta])) {
157	$block['subject'] = t('Related content: !type', array('!type' => $node_types[$delta]));
158	$block['content'] = theme('relations_node_block', $node, array('type' => $delta));
159	}
160	break;
161	}
162	}
163	return $block;
164	}
165	}
166
167	/**
168	* Implementation of hook_forms().
169	*/
170	function relations_forms() {
171	return array(
172	'relations_node_form' => array(
173	'callback' => 'relations_node_form',
174	),
175	);
176	}
177
178	/**
179	* Implementation of hook_theme()
180	*/
181	function relations_theme() {
182	return array(
183	'relations_node_form' => array(
184	'arguments' => array('node' => NULL),
185	'file' => 'relations.pages.inc',
186	),
187	'relations_node_table' => array(
188	'arguments' => array('node' => NULL),
189	'file' => 'relations.pages.inc',
190	),
191	'relations_node_block' => array(
192	'arguments' => array('node' => NULL),
193	'file' => 'relations.pages.inc',
194	),
195	'relations_node_list' => array(
196	'arguments' => array('nodes' => NULL),
197	'file' => 'relations.pages.inc',
198	),
199	'relations_admin_settings' => array(
200	'arguments' => array('form' => NULL),
201	'file' => 'relations.admin.inc',
202	),
203	);
204	}
205
206	/**
207	* Implementation of hook_form_alter().
208	*
209	* @see relations_nodeapi()
210	*/
211	function relations_form_alter(&$form, $form_state, $form_id) {
212	if (isset($form['type']) && isset($form['#node'])) {
213	$node = $form['#node'];
214
215	if ($form['type']['#value'] .'_node_form' == $form_id && relations_is_node_type_enabled($node->type)) {
216	if (!variable_get('relations_ui_node_edit', '1')) {
217	return; // configured at <admin/settings/rdf/relations>
218	}
219
220	$form['relations'] = array(
221	'#type' => 'fieldset',
222	'#access' => user_access('create node relations'),
223	'#title' => t('Related content'),
224	'#collapsible' => TRUE,
225	'#collapsed' => TRUE,
226	'#prefix' => '<div class="relations">',
227	'#suffix' => '</div>',
228	'#weight' => 20,
229	);
230	$form['relations']['relations_blocks'] = array(
231	'#type' => 'checkboxes',
232	'#title' => t('Enabled related content types'),
233	'#default_value' => relations_get_node_types($node),
234	'#options' => array_map('t', array_intersect_key(node_get_types('names'), relations_get_node_types())),
235	'#description' => t('Select which types of related content you wish to display when this node is viewed.'),
236	);
237
238	module_load_include('inc', 'relations', 'relations.pages');
239	$form['relations']['relations_table'] = relations_node_form(array(), $node, TRUE);
240	}
241	}
242	}
243
244	/**
245	* Implementation of hook_nodeapi().
246	*/
247	function relations_nodeapi(&$node, $op, $arg = 0) {
248	if (relations_is_node_type_enabled($node->type)) {
249	switch ($op) {
250	case 'prepare':
251	if (empty($_POST)) {
252	$_SESSION['relations'] = array('create' => array(), 'delete' => array());
253	}
254	$node->relations_blocks = relations_get_node_types($node);
255	break;
256	case 'insert':
257	case 'update':
258	if (!empty($_SESSION['relations']['delete'])) {
259	foreach ($_SESSION['relations']['delete'] as $nid => $title) {
260	relations_api_delete($node->nid, $nid);
261	}
262	}
263	if (!empty($_SESSION['relations']['create'])) {
264	foreach ($_SESSION['relations']['create'] as $nid => $title) {
265	relations_api_create($node->nid, $nid);
266	}
267	}
268	unset($_SESSION['relations']);
269	if (isset($node->relations_blocks)) {
270	$node->relations_blocks = array_filter($node->relations_blocks, 'is_string');
271	variable_set('relations_blocks_node_'. $node->nid, $node->relations_blocks);
272	}
273	break;
274	case 'delete':
275	variable_del('relations_blocks_node_'. $node->nid);
276	break;
277	}
278	}
279	}
280
281	//////////////////////////////////////////////////////////////////////////////
282	// Picker API hooks
283
284	function relations_picker_access($node2) {
285	// When adding relations to an existing node:
286	if (!empty($_SERVER['HTTP_REFERER']) && preg_match('!node/(\d+)/!', $_SERVER['HTTP_REFERER'], $matches)) {
287	$node1 = node_load((int)$matches[1]);
288	return relations_allowed($node1, $node2);
289	}
290	// When adding relations to a node to be created:
291	if (!empty($_SESSION['relations'])) {
292	return relations_allowed(TRUE, $node2);
293	}
294	}
295
296	//////////////////////////////////////////////////////////////////////////////
297	// Relations API implementation
298
299	function relations_menu_access($node, $perm) {
300	return user_access($perm) && (empty($node) \|\| relations_is_node_type_enabled($node->type));
301	}
302
303	function relations_is_node_type_enabled($type) {
304	return array_search($type, relations_get_node_types());
305	}
306
307	function relations_get_node_types($node = NULL) {
308	return isset($node->nid) ?
309	variable_get('relations_blocks_node_'. $node->nid, relations_get_node_types(NULL)) :
310	array_filter(variable_get('relations_node_types', array()), 'is_string');
311	}
312
313	function relations_get_predicate() {
314	return variable_get('relations_predicate', RELATIONS_PREDICATE);
315	}
316
317	function relations_get_predicates($op = NULL) {
318	switch ($op) {
319	case 'keys':
320	return array_combine(array_keys(relations_get_predicates()), array_fill(0, count(relations_get_predicates()), ''));
321	default:
322	return array(
323	relations_get_predicate() => (object)array('title' => t('See also'), 'uri' => relations_get_predicate(), 'bidirectional' => TRUE),
324	);
325	}
326	}
327
328	function relations_rdf_options() {
329	return array('repository' => RELATIONS_REPOSITORY);
330	}
331
332	function relations_node_url($nid) {
333	return url('node/'. $nid, array('alias' => TRUE, 'absolute' => TRUE));
334	}
335
336	function relations_api_query($url) {
337	// TODO: this breaks encapsulation; should probably implement multi-queries directly in RDF API.
338	return array_merge(
339	rdf_query(rdf_uri($url), NULL, NULL, relations_rdf_options())->to_array(),
340	rdf_query(NULL, NULL, rdf_uri($url), relations_rdf_options())->to_array());
341	}
342
343	function relations_api_lookup($node, array $options = array()) {
344	global $user;
345	$account = empty($options['user']) ? $user : (is_object($options['user']) ? $options['user'] : user_load($options['user']));
346	$nid = is_object($node) ? $node->nid : (int)$node;
347
348	// Support for filtering related nodes by one or more content types:
349	if (!empty($options['type'])) {
350	$options['type'] = is_array($options['type']) ? $options['type'] : array($options['type']);
351	}
352
353	$nodes = array();
354	$results = relations_api_query(relations_node_url($nid));
355	foreach ($results as $triple) {
356	list($s, $p, $o) = $triple;
357	if ((preg_match('!node/'. $nid .'$!', (string)$s) && preg_match('!node/(\d+)$!', (string)$o, $matches)) \|\|
358	(preg_match('!node/'. $nid .'$!', (string)$o) && preg_match('!node/(\d+)$!', (string)$s, $matches))) {
359	if (($node = node_load($matches[1])) && node_access('view', $node, $account)) {
360	if (empty($options['type']) \|\| in_array($node->type, $options['type'])) {
361	$nodes[$node->nid] = $node;
362	}
363	}
364	}
365	}
366	return $nodes;
367	}
368
369	function relations_api_create($node1, $node2, array $options = array()) {
370	$nid1 = is_object($node1) ? $node1->nid : (int)$node1;
371	$nid2 = is_object($node2) ? $node2->nid : (int)$node2;
372
373	// Make sure we never insert duplicate statements:
374	if (($existing = relations_api_lookup($nid1, $options)) && isset($existing[$nid2])) {
375	return TRUE;
376	}
377
378	$url1 = rdf_uri(relations_node_url($nid1));
379	$url2 = rdf_uri(relations_node_url($nid2));
380	return rdf_insert($url1, relations_get_predicate(), $url2, relations_rdf_options());
381	}
382
383	function relations_api_delete($node1, $node2, array $options = array()) {
384	$nid1 = is_object($node1) ? $node1->nid : (int)$node1;
385	$nid2 = is_object($node2) ? $node2->nid : (int)$node2;
386
387	$url1 = rdf_uri(relations_node_url($nid1));
388	$url2 = rdf_uri(relations_node_url($nid2));
389	rdf_delete($url1, relations_get_predicate(), $url2, relations_rdf_options());
390	rdf_delete($url2, relations_get_predicate(), $url1, relations_rdf_options());
391	return TRUE;
392	}
393
394	function relations_allowed($node1, $node2) {
395	// Must have edit access to either the source or destination node, and
396	// view access to the target node (view access to the source node is
397	// implied):
398	$editor1 = is_object($node1) ? node_access('update', $node1) : (bool)$node1;
399	$editor2 = node_access('update', $node2);
400	$reader2 = node_access('view', $node2);
401	return ($editor1 \|\| $editor2) && $reader2;
402	}