taxonomy.module

<?php
// $Id$

function taxonomy_system($field){
  $system["description"] = t("Enables the organization of content into categories.");
  return $system[$field];
}

function taxonomy_feed() {
  global $id, $or, $and, $type;

  if ($type == "voc") {
    //TODO - vocabulary feed. How to represent an outline in XML?
  }
  else {
    if ($or) {
      foreach ((explode(",", $or)) as $t) {
        $terms[] = "'". check_query($t) ."'";
      }
      $result = db_query("SELECT DISTINCT(n.nid), type FROM node n LEFT JOIN term_node r ON n.nid = r.nid WHERE tid IN (". implode(",", $terms) .") AND status = '1' ORDER BY static DESC, created DESC LIMIT 15");
      $term = taxonomy_get_term($or);
    }
    else if ($and) {
      foreach ((explode(",", $and)) as $t) {
        $terms[] = "'". check_query($t) ."'";
      }
      $result = db_query("SELECT n.nid, type, count(*) AS c FROM node n LEFT JOIN term_node r ON n.nid = r.nid WHERE tid IN (". implode(",", $terms) .") AND status = '1' GROUP BY n.nid, n.type HAVING c = ". count($terms) ." ORDER BY static DESC, created DESC LIMIT 15");
      $term = taxonomy_get_term($and);
    }
    else {
      return node_feed();
    }

    $channel["title"] = variable_get("site_name", "drupal") ." - ". $term->name;
    $channel["link"] = path_uri() ."index.php?or=$or";
    $channel["description"] = $term->description;

    node_feed($result, $channel);
  }
}

function taxonomy_perm() {
  return array("administer taxonomy");
}

function taxonomy_link($type) {
  if ($type == "admin" && user_access("administer taxonomy")) {
    $links[] = la(t("taxonomy"), array("mod" => "taxonomy"));
  }

  return $links ? $links : array();
}

/*
** admin pages (form, save, overview)
*/

function taxonomy_form_vocabulary($edit = array()) {
  foreach (module_list() as $name) {
    if (module_hook($name, "node")) {
      $nodetypes[$name] = $name;
    }
  }

  $form .= form_textfield("Vocabulary name", "name", $edit["name"], 50, 64, "Required.  The name for this vocabulary.  Example: 'Topic'.");
  $form .= form_textarea("Description", "description", $edit["description"], 60, 5, "Optional.  Description of the vocabulary, can be used by modules.");
  $form .= form_select("Types", "types", explode(",", $edit["types"]), $nodetypes, "Required.  A list of node types you want to associate this vocabulary with.", "", 1);
  $form .= form_checkbox("Related terms", "relations", 1, $edit["relations"], "Optional. Allows ". la("related terms", array("mod" => "taxonomy", "op" => "help"), "relatedterms") ." in this vocabulary.");
  $form .= form_select("Hierarchy", "hierarchy", $edit["hierarchy"], array("Disabled", "Single", "Multiple"), "Optional. Allows ". la("a tree-like hierarchy", array("mod" => "taxonomy", "op" => "help"), "hierarchy") ." between terms of this vocabulary.", "", 0);
  $form .= form_checkbox("Multiple select", "multiple", 1, $edit["multiple"], "Optional. Allows nodes to have more than one term in this vocabulary.");
  $form .= form_checkbox("Required", "required", 1, $edit["required"], "If enabled every node <b>must</b> have at least one term in this vocabulary");
  $form .= form_textfield("Weight", "weight", $edit["weight"], 3, 3, "Optional. In listings, the heavier vocabularies will sink and the lighter vocabularies will be positioned nearer the top.");
  $form .= form_submit("Submit");

  if ($edit["vid"]) {
    $form .= form_submit("Delete");
    $form .= form_hidden("vid", $edit["vid"]);
  }

  return form($form);
}

function taxonomy_save_vocabulary($edit) {
  $data = array("name" => $edit["name"], "types" => @implode(",", $edit["types"]), "description" => $edit["description"], "multiple" => $edit["multiple"], "required" => $edit["required"], "hierarchy" => $edit["hierarchy"], "relations" => $edit["relations"], "weight" => $edit["weight"]);

  if ($edit["vid"] && $edit["name"]) {
    db_query("UPDATE vocabulary SET ". _prepare_update($data) ." WHERE vid = '". check_input($edit["vid"]) ."'");
  }
  else if ($edit["vid"]) {
    taxonomy_del_vocabulary($edit["vid"]);
  }
  else {
    db_query("INSERT INTO vocabulary ". _prepare_insert($data, 1) ." VALUES ". _prepare_insert($data, 2));
  }
}

function taxonomy_del_vocabulary($vid) {
  db_query("DELETE FROM vocabulary WHERE vid = '%s'", $vid);
  $result = db_query("SELECT tid FROM term_data WHERE vid = '%s'", $vid);
  while ($term = db_fetch_object($result)) {
    taxonomy_del_term($term->tid);
  }
}

function taxonomy_form_term($edit = array()) {
  global $vocabulary_id;
  if (!$vocabulary_id) {
    $vocabulary_id = $edit["vid"];
  }
  $vocabulary = taxonomy_get_vocabulary($vocabulary_id);
  $form = form_textfield("Term name", "name", $edit["name"], 50, 64, "Required.  The name for this term.  Example: 'Linux'.");
  $form .= form_textarea("Description", "description", $edit["description"], 60, 5, "Optional.  Description of the term, can be used by modules.");

  if ($vocabulary->relations) {
    $form .= _taxonomy_term_select("Related terms", "relations", array_keys(taxonomy_get_related($edit["tid"])), $vocabulary_id, "Optional.", 1, "<none>", array($edit["tid"]));
  }


  if ($vocabulary->hierarchy) {
    $parent = array_keys(taxonomy_get_parents($edit["tid"]));
    taxonomy_get_tree($vocabulary_id, $children, $edit["tid"]);
    // you can't be son of yourself or your children
    $exclude = array_keys($children);
    $exclude[] = $edit["tid"];
    if ($vocabulary->hierarchy == 1) {
      $form .= _taxonomy_term_select("Parent", "parent", $parent, $vocabulary_id, "Required. ". la("Parent term", array("mod" => "taxonomy", "op" => "help"), "parent") .".", 0, "<root>", $exclude);
    }
    elseif ($vocabulary->hierarchy == 2) {
      $form .= _taxonomy_term_select("Parents", "parent", $parent, $vocabulary_id, "Required. ". la("Parent terms", array("mod" => "taxonomy", "op" => "help"), "parent") .".", 1, "<root>", $exclude);
    }
  }

  $form .= form_textarea("Synonyms", "synonyms", implode("\n", taxonomy_get_synonyms($edit["tid"])), 30, 5, "Optional. ". la("Synonyms", array("mod" => "taxonomy", "op" => "help"), "synonyms") ." of this term, one synonym per line.");
  $form .= form_textfield("Weight", "weight", $edit["weight"], 3, 3, "Optional. In listings, the heavier terms will sink and the lighter terms will be positioned nearer the top.");
  $form .= form_hidden("vid", $vocabulary->vid);
  $form .= form_submit("Submit");

  if ($edit["tid"]) {
    $form .= form_submit("Delete");
    $form .= form_hidden("tid", $edit["tid"]);
  }

  return form($form);
}

function taxonomy_save_term($edit) {
 if ($edit["tid"] && $edit["name"]) {
    $data = array("name" => $edit["name"], "description" => $edit["description"], "weight" => $edit["weight"]);

    db_query("UPDATE term_data SET ". _prepare_update($data) ." WHERE tid = '%s'", $edit["tid"]);
  }
  else if ($edit["tid"]) {
    taxonomy_del_term($edit["tid"]);
  }
  else {
    $edit["tid"] = db_result(db_query("SELECT MAX(tid) + 1 FROM term_data"));
    if (!$edit["tid"]) {
      // first term
      $edit["tid"] = 1;
    }
    $data = array("tid" => $edit["tid"], "name" => $edit["name"], "description" => $edit["description"], "vid" => $edit["vid"], "weight" => $edit["weight"]);
    db_query("INSERT INTO term_data ". _prepare_insert($data, 1) ." VALUES ". _prepare_insert($data, 2));
  }

  // relations (seem very powerful, but I have to understand it completely)
  db_query("DELETE FROM term_relation WHERE tid1 = '%s' OR tid2 = '%s'", $edit["tid"], $edit["tid"]);
  if ($edit["relations"]) {
    foreach ($edit["relations"] as $related_id) {
      if ($related_id != 0) {
        $rel_q[] = "('". check_query($edit["tid"]) ."', '". check_query($related_id) ."')";
      }
    }
    if ($rel_q) {
      $related_query = implode(", ", $rel_q);
      db_query("INSERT INTO term_relation (tid1, tid2) VALUES $related_query");
    }
  }

  // hierarchy
  db_query("DELETE FROM term_hierarchy WHERE tid = '%s'", $edit["tid"]);
  if (!isset($edit["parent"])) {
    $edit["parent"] = 0;
  }
  if (is_array($edit["parent"])) {
    foreach ($edit["parent"] as $parent) {
      $sql[] = "('". check_query($edit["tid"]) ."', '". check_query($parent) ."')";
    }
    db_query("INSERT INTO term_hierarchy (tid, parent) VALUES ". implode(", ", $sql));
  }
  else {
    db_query("INSERT INTO term_hierarchy (tid, parent) VALUES ('%s', '%s')", $edit["tid"], $edit["parent"][0]);
  }

  // synonyms (very cool idea indeed)
  db_query("DELETE FROM term_synonym WHERE tid = '%s'", $edit["tid"]);
  if ($edit["synonyms"]) {
    foreach (explode ("\n", $edit["synonyms"]) as $synonym) {
      $syn_q[] = "('". check_query($edit["tid"]) ."', '". check_query(chop($synonym)) ."')";
    }
    $synonyms_query = implode(", ", $syn_q);
    db_query("INSERT INTO term_synonym (tid, name) VALUES $synonyms_query");
  }
}

function taxonomy_del_term($tid) {
  db_query("DELETE FROM term_data WHERE tid = '%s'", $tid);
  db_query("DELETE FROM term_hierarchy WHERE tid = '%s'", $tid);
  db_query("DELETE FROM term_relation WHERE tid1 = '%s' OR tid2 = '%s'", $tid, $tid);
  db_query("DELETE FROM term_synonym WHERE tid = '%s'", $tid);
  db_query("DELETE FROM term_node WHERE tid = '%s'", $tid);
}

function taxonomy_overview() {
  global $tree;

  $output .= "<h3>Vocabularies overview</h3>";
  $output .= "<table border=\"1\" cellpadding=\"2\" cellspacing=\"2\">\n";
  $output .= " <tr><th>name</th><th>node types</th><th>operations</th></tr>\n";

  $vocabularies = taxonomy_get_vocabularies();
  foreach ($vocabularies as $vocabulary) {
    $links = array();
    $links[] = la(t("edit vocabulary"), array("mod" => "taxonomy", "type" => "vocabulary", "op" => "edit", "id" => $vocabulary->vid));
    $links[] = la(t("add term"), array("mod" => "taxonomy", "op" => "add", "type" => "leaf", "vocabulary_id" => $vocabulary->vid));
    $links[] = la(t("preview form"), array("mod" => "taxonomy", "type" => "vocabulary", "op" => "preview", "id" => $vocabulary->vid));

    $output .= " <tr><td>". check_output($vocabulary->name) ."</td><td>". check_output($vocabulary->types) ."</td><td>". implode(" | ", $links) ."</td></tr>\n";

    unset($tree);
    taxonomy_get_tree($vocabulary->vid, $tree);
    if ($tree) {
      $output .= "<tr><td colspan=\"3\"><table><tr><td>";
      foreach ($tree as $term) {
        $output .= "<tr><td>". la(_taxonomy_depth($term->depth) . check_output($term->name), array("mod" => "taxonomy", "op" => "edit", "type" => "term", "id" => check_output($term->tid))) ."</td></tr>";
      }
      $output .= "</td></tr></table></td></tr>\n";
    }
  }
  $output .= "</table>\n";

  return $output;
}

function taxonomy_form($vocabulary_id, $value = 0) {
  $vocabulary = taxonomy_get_vocabulary($vocabulary_id);
  if ($vocabulary->required) {
    $verb = "must";
    $blank = 0;
  }
  else {
    $verb = "can";
    $blank = t("<none>");
  }

  if ($vocabulary->multiple) {
    $description = t("You $verb choose one or more terms for this node.");
    $multiple = 1;
  }
  else {
    $description = t("You $verb choose one term for this node.");
    $multiple = 0;
  }
  return _taxonomy_term_select($vocabulary->name, "taxonomy", $value, $vocabulary_id, $description, $multiple, $blank);
}

/*
** API functions
*/

// return array of vocabularies, as objects
function taxonomy_get_vocabularies($type = '', $key = "vid") {
  if ($type) {
    $result = db_query("SELECT * FROM vocabulary WHERE types LIKE '%%%s%%' ORDER BY weight, name", $type);
  }
  else {
    $result = db_query("SELECT * FROM vocabulary ORDER BY weight, name");
  }
  $vocabularies = array();
  while ($voc = db_fetch_object($result)) {
    $vocabularies[$voc->$key] = $voc;
  }
  return $vocabularies;
}

// return form with current term
function taxonomy_node_form($type, $node = '') {
  if (!$node->taxonomy) {
    if ($node->nid) {
      $terms = array_keys(taxonomy_node_get_terms($node->nid));
    }
    else {
      $terms = 0;
    }
  }
  else {
    $terms = $node->taxonomy;
  }

  $c = db_query("SELECT * FROM vocabulary WHERE types LIKE '%%%s%%' ORDER BY weight, name", $type);
  while ($vocabulary = db_fetch_object($c)) {
    $result[] .= taxonomy_form($vocabulary->vid, $terms);
  }
  return $result ? $result : array();
}

// return 1 if node identified by $nid contains a taxonomy term identified by $tid in his body or title
function taxonomy_node_has_term($nid, $tid) {
  $term_name = db_result(db_query("SELECT name FROM term_data WHERE tid = '%s'", $tid));

  return db_result(db_query("SELECT COUNT(n.nid) FROM node n WHERE n.nid = '%s' AND ((n.body LIKE '%%%s%%') OR (n.body LIKE '%%%s%%'))", $nid, $term_name, $term_name));
}

// return array of terms of a node beloging to a particular vocabulary identified by $vid
function taxonomy_node_get_terms_by_vocabulary($nid, $vid, $key = "tid") {
  $result = db_query("SELECT t.* FROM term_data t, term_node r WHERE t.tid = r.tid AND t.vid = '%s' AND r.nid = '%s' ORDER BY weight", $vid, $nid);
  $terms = array();
  while ($term = db_fetch_object($result)) {
    $terms[$term->$key] = $term;
  }
  return $terms;
}

// return array of terms of a node
function taxonomy_node_get_terms($nid, $key = "tid") {
  static $terms;

  if (!$terms[$nid]) {
    $result = db_query("SELECT t.* FROM term_data t, term_node r WHERE r.tid = t.tid AND r.nid = '%s' ORDER BY weight", $nid);
    $terms[$nid] = array();
    while ($term = db_fetch_object($result)) {
      $terms[$nid][$term->$key] = $term;
    }
  }
  return $terms[$nid];
}

// save terms of a node
function taxonomy_node_save($nid, $terms) {
  taxonomy_node_delete($nid);

  if ($terms) {
    foreach ($terms as $t) {
      $query[] = "('". check_query($nid) ."', '". check_query($t) ."')";
    }
    db_query("INSERT INTO term_node (nid, tid) VALUES ". implode(", ", $query));
  }
}

// clean up terms
function taxonomy_node_delete($nid) {
  db_query("DELETE FROM term_node WHERE nid = '%s'", $nid);
}

// relations: return array of related terms
function taxonomy_get_related($tid, $key = "tid") {
  if ($tid) {
    $result = db_query("SELECT t.*, tid1, tid2 FROM term_relation, term_data t WHERE (t.tid = tid1 OR t.tid = tid2) AND (tid1 = '%d' OR tid2 = '%d') AND t.tid != '%d' ORDER BY weight", $tid, $tid, $tid);
    $related = array();
    while ($term = db_fetch_object($result)) {
      $related[$term->$key] = $term;
    }
    return $related;
  }
  else {
    return array();
  }
}

// hierarchy: get parent terms
function taxonomy_get_parents($tid, $key = "tid") {
  if ($tid) {
    $result = db_query("SELECT t.* FROM term_hierarchy h, term_data t WHERE h.parent = t.tid AND h.tid = '%s' ORDER BY weight, name", $tid);
    $parents = array();
    while ($parent = db_fetch_object($result)) {
      $parents[$parent->$key] = $parent;
    }
    return $parents;
  }
  else {
    return array();
  }
}

// hierarchy: get children
function taxonomy_get_children($tid, $vid = 0, $key = "tid") {
  if ($vid) {
    $result = db_query("SELECT t.* FROM term_hierarchy h, term_data t WHERE t.vid = '%s' AND h.tid = t.tid AND h.parent = '%s' ORDER BY weight, name", $vid, $tid);
  }
  else {
    $result = db_query("SELECT t.* FROM term_hierarchy h, term_data t WHERE h.tid = t.tid AND parent = '%s' ORDER BY weight", $tid);
  }
  $children = array();
  while ($term = db_fetch_object($result)) {
    $children[$term->$key] = $term;
  }
  return $children;
}

// hierarchy: get whole family, with tid, parent and depth; useful to show
function taxonomy_get_tree($vocabulary_id, &$tree, $parent = 0, $depth = -1, $key = "tid") {
  static $children, $terms;
  if ($depth == -1) {
    $children = array();
    $tree = array();
    // $terms = array();   // we should be able to safely do this
  }
  $depth++;
  if ($vocabulary_id) {
    if (!$children) {
      $result = db_query("SELECT t.*, parent FROM term_data t, term_hierarchy h WHERE t.tid = h.tid AND t.vid = '%s' ORDER BY weight, name", $vocabulary_id);
      while ($term = db_fetch_object($result)) {
        $children[$term->parent][] = $term->tid;
        $terms[$term->tid] = $term;
      }
    }
    if ($children[$parent]) {
      foreach ($children[$parent] as $child) {
        $terms[$child]->depth = $depth;
        $tree[] = $terms[$child];
        taxonomy_get_tree($vocabulary_id, $tree, $child, $depth, $key);
      }
    }
  }
  else {
    return 0;
  }
}

// synonyms: return array of synonyms
function taxonomy_get_synonyms($tid) {
  if ($tid) {
    $result = db_query("SELECT name FROM term_synonym WHERE tid = '%s'", $tid);
    while ($synonym = db_fetch_array($result)) {
      $synonyms[] = $synonym["name"];
    }
    return $synonyms ? $synonyms : array();
  }
  else {
    return array();
  }
}

// synonyms: return original term
function taxonomy_get_synonym_root($term) {
  return db_fetch_object(db_query("SELECT * FROM term_synonym s, term_data t WHERE t.tid = s.tid AND s.name = '%s'", $term));
}

// given a term id, count number of nodes in it
function taxonomy_term_count_nodes($tid) {
  static $count;

  if (!$count) {
    $result = db_query("SELECT tid, COUNT(*) AS c FROM term_node GROUP BY tid");
    while ($term = db_fetch_object($result)) {
      $count[$term->tid] = $term->c;
    }
  }

  foreach (_taxonomy_term_children($tid) as $c) {
    $children_count += taxonomy_term_count_nodes($c);
  }
  return $count[$tid] + $children_count;
}

// helper for above function
function _taxonomy_term_children($tid) {
  static $children;

  if (!$children) {
    $result = db_query("SELECT tid, parent FROM term_hierarchy");
    while ($term = db_fetch_object($result)) {
      $children[$term->parent][] = $term->tid;
    }
  }
  return $children[$tid] ? $children[$tid] : array();
}

function taxonomy_get_vocabulary($vid) {
  // simple cache using a static var?
  return db_fetch_object(db_query("SELECT * FROM vocabulary WHERE vid = '%s'", $vid));
}

function taxonomy_get_term($tid) {
  // simple cache using a static var?
  return db_fetch_object(db_query("SELECT * FROM term_data WHERE tid = '%s'", $tid));
}

/*
** service functions
*/

function _taxonomy_term_select($title, $name, $value, $vocabulary_id, $description, $multiple, $blank, $exclude = array()) {
  taxonomy_get_tree($vocabulary_id, $tree);

  if ($blank) {
    $options[0] = $blank;
  }

  if ($tree) {
    foreach ($tree as $term) {
      if (!in_array($term->tid, $exclude)) {
        $options[$term->tid] = _taxonomy_depth($term->depth, '-').$term->name;
      }
    }
    if (!$blank && !$value) {
      // required but without a predefined value, so set first as predefined
      $value = $tree[0]->tid;
    }
  }

  if (count($options) > 0) {
    foreach ($options as $key=>$choice) {
      $select .= "<option value=\"$key\"". (is_array($value) ? (in_array($key, $value) ? " selected=\"selected\"" : "") : ($key == $value ? " selected=\"selected\"" : "")) .">". check_form($choice) ."</option>";
    }

    $size = min(12, count($options));

    return form_item($title, "<select name=\"edit[$name][]\"". ($multiple ? " multiple size=\"$size\"" : "") . ($extra ? " $extra" : "") .">$select</select>", $description);
  }
}

function _taxonomy_depth($depth, $graphic = '--') {
  for ($n = 0; $n < $depth; $n++) {
    $result .= $graphic;
  }
  return $result;
}

function _prepare_update($data) {
  foreach ($data as $key => $value) {
    $q[] = "$key = '". check_query($value) ."'";
  }
  $result = implode(", ", $q);
  return $result;
}

function _prepare_insert($data, $stage) {
  if ($stage == 1) {
    $result = implode(", ", array_keys($data));
  }
  else {
    foreach (array_values($data) as $value) {
      $q[] = "'". check_query($value) ."'";
    }
    $result = implode(", ", $q);
  }
  return "($result)";
}

function taxonomy_page() {
  global $op;

  switch ($op) {
    case "feed":
      taxonomy_feed();
      break;
    default:
       // TODO: pretty display of all vocabularies
  }
}

/*
** admin
*/

function taxonomy_admin() {
  global $edit, $type, $op, $id, $tree;

  if (user_access("administer taxonomy")) {
    $links[] = la(t("add new vocabulary"), array("mod" => "taxonomy", "op" => "add", "type" => "vocabulary"));
    $links[] = la(t("overview"), array("mod" => "taxonomy"));
    $links[] = la(t("help"), array("mod" => "taxonomy", "op" => "help"));

    print "<small>". implode(" | ", $links) ."</small><hr>\n";

    switch ($op) {
      case "add":
        if ($type == "vocabulary") {
          print taxonomy_form_vocabulary();
        }
        else {
          print taxonomy_form_term();
        }
        break;
      case "edit":
        if ($type == "vocabulary") {
          print taxonomy_form_vocabulary(object2array(taxonomy_get_vocabulary($id)));
        }
        else {
          print taxonomy_form_term(object2array(taxonomy_get_term($id)));
        }
        break;
      case "preview":
        print taxonomy_form($id);
        break;
      case "help":
        print taxonomy_help();
        break;
      case "Delete":
        $edit["name"] = 0;
        // fall through:
      case "Submit":
        if ($type == "vocabulary") {
          print status(taxonomy_save_vocabulary($edit));
        }
        else {
          print status(taxonomy_save_term($edit));
        }
        // fall through:
      default:
        print taxonomy_overview();
    }
  }
  else {
    print message_access();
  }
}

function taxonomy_help() {
  ?>

  <h3>Background</h3>
  <p>Classifying nodes allows for the organization of content into categories and subcategories of description. These categories can be used to organize and retrieve similarly described content. Drupal's <i>taxonomy.module</i> is an extremely flexible classification system that allows for multiple lists of categories for classification (controlled vocabularies) and offers the possibility of creating thesauri (controlled vocabularies that indicate the relationship of terms) and taxonomies (controlled vocabularies where relationships are indicated hierarchically). For details about <a href="http://www.eleganthack.com/archives/002165.html#002165">classification types</a> and insight into the development of <i>taxonomy.module</i>, see this <a href="http://www.drupal.org/node.php?id=55">drupal.org discussion</a>.</p>

  <h3>An example taxonomy: food</h3>
  <p>Dairy <br />
  --Milk <br />
  Drink <br />
  --Alchohol <br />
  --Pop <br />
  --Milk<br />
  Meat <br />
  --Beef <br />
  --Chicken <br />
  --Lamb <br />
  Spices <br />
  --Sugar</p>
  <p><b>Notes</b></p>
   <ul>
   <li>The term <i>Milk</i> appears within both <i>Dairy</i> and <i>Drink</i>.  This is an example of <i>nmultiple parents</i> for a term.</li>
   <li>The order of siblings (e.g. <i>Beef</i>, <i>Chicken</i>, <i>Lamb</i>) in the taxonomy may be controlled with the <i>weight</i> parameter. </li>
  </ul>

  <h3>Vocabularies</h3>
  <p>When you create a controlled vocabulary you are creating a set of terms to use for describing content (known as descriptors in indexing lingo). Drupal allows you to describe each node of content (blog, story, etc.) using one or many of these terms. For simple implementations, you might create a set of categories without subcategories, similar to <a href="http://www.slashdot.com/">Slashdot's</a> sections.  For more complex implementations, you might create a hierarchical list of categories such as the example <i>Food</i> taxonomy above.</p>

  <h4>Setting up a vocabulary</h4>
  <p>When you set up a controlled vocabulary, you will be asked to enter some descriptive data and define the attributes of this vocabulary. For example, if you select the <i>hierarchy</i> option, you will be defining a taxonomy or a thesaurus. If you select <i>related terms</i> option, you are allowing the definition of related terms as in a thesaurus. Selecting <i>multiple select</i> will allow you to describe a node using more than one term. That node will then appear in each term's page, thus increasing the chance that a user will find it.</p>

  <i>Vocabulary name</i><br />Required. The name for this vocabulary. Example: <i>Dairy</i>.<br />
  <br />
  <i>Description</i><br />Optional. Description of the vocabulary, can be used by modules and feeds.<br />
  <br />
  <i>Types</i><br />Required. The list of node types you want to associate this vocabulary with. Some available types are: blog, book, forum, page, story.<br />
  <br />
  <i><a name="relatedterms"></a>Related terms</i><br />Allows relationships between terms within this vocabulary. Think of these as <i>see also</i>-references.<br />
  <br />
  <i><a name="hierarchy"></a>Hierarchy</i><br />Allows a tree-like taxonomy, as in our <i>Foods</i> example above<br />
  <br />
  <i>Multiple select</i><br />Allows nodes to be described using more than one term. Nodes may then appear on multiple taxonomy pages.<br />

  <h4>Adding terms to a vocabulary</h4>
<p>The options you see when adding a term to a vocabulary will depend on what you selected for <i>related terms</i>, <i>hierarchy </i>and <i>multiple select</i> when you created the corrosponding vocabulary.</p>

  <i>Term name</i><br />Required. The name for this term. Example: <i>Milk</i><br />
  <br />
  <i>Description</i><br />Optional. Description of the term that may be used by modules and RSS feeds.  This is synonymous with a 'scope note'.<br />
  <br />
  <i><a name="parent"></a>Parent</i><br />Required. Select the term under which this term is a subset -- the branch of the hierarchy that this term belongs under. This is also known as the "Broader term" indicator used in thesauri.<br />
  <br />
  <i><a name="synonyms"></a>Synonyms</i><br />Optional. Enter synonyms for this term, one synonym per line. Synonyms can be used for variant spellings, acronyms, and other terms that have the same meaning as the added term, but which are not explicitly listed in this thesaurus (i.e. <i>unauthorized terms</i>).<br />

  <h3>Displaying nodes organized by term(s)</h3>
  <p>In order to view the nodes associated with a term or a collection of terms, you should browse to a properly formed URL. For example, see <a href="<?php print path_uri().drupal_url(array("mod" => "node", "or" => "1,2"), "module"); ?>"><?php print path_uri().drupal_url(array("mod" => "node", "or" => "1,2"), "module"); ?></a>.  Taxonomy URLs always contain  a term ID or list of term IDs at the end of the URL (aka <i>querystring</i>). You may learn the term ID for a given term by hovering over that term in the <? echo la("taxonomy overview", array("mod" => "taxonomy")) ?> page in the Admin and noting the number after the querystring parameter called <i>tid</i>.  If you wish to see nodes from a collection of term IDs, separate each term ID with a comma.  Also, the name of the querystring parameter may be <i>or</i> or <i>and</i>: <i>or</i> shows nodes which appear in <b>any</b> of the term IDs while <i>and</i> shows nodes in <b>all</b> the specified term IDs.  Thus, <i>or</i> is less specific than <i>and</i>.</p>

  <h3>RSS feeds</h3>
  <p>Every term, or collection of terms, provides an <a href="http://backend.userland.com/stories/rss091">RSS</a> feed to which interested users may subscribe. The URL format for an sample RSS feed is <a href="<?php print path_uri().drupal_url(array("mod" => "node", "op" => "feed", "or" => "1,2"), "module"); ?>"><?php print path_uri().drupal_url(array("mod" => "node", "op" => "feed", "or" => "1,2"), "module"); ?></a>.</p>
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