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Drupal example source code file (search.extender.inc)

This example Drupal source code file (search.extender.inc) is included in the DevDaily.com "Drupal Source Code Warehouse" project. The intent of this project is to help you "Learn Drupal by Example".

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The search.extender.inc Drupal example source code

<?php
// $Id: search.extender.inc,v 1.10 2010/11/22 07:32:12 webchick Exp $

/**
 * @file
 * Search query extender and helper functions.
 */

/**
 * Do a query on the full-text search index for a word or words.
 *
 * This function is normally only called by each module that supports the
 * indexed search (and thus, implements hook_update_index()).
 *
 * Results are retrieved in two logical passes. However, the two passes are
 * joined together into a single query. And in the case of most simple
 * queries the second pass is not even used.
 *
 * The first pass selects a set of all possible matches, which has the benefit
 * of also providing the exact result set for simple "AND" or "OR" searches.
 *
 * The second portion of the query further refines this set by verifying
 * advanced text conditions (such as negative or phrase matches).
 *
 * The used query object has the tag 'search_$module' and can be further
 * extended with hook_query_alter().
 */
class SearchQuery extends SelectQueryExtender {
  /**
   * The search query that is used for searching.
   *
   * @var string
   */
  protected $searchExpression;

  /**
   * Type of search (search module).
   *
   * This maps to the value of the type column in search_index, and is equal
   * to the machine-readable name of the module that implements
   * hook_search_info().
   *
   * @var string
   */
  protected $type;

  /**
   * Positive and negative search keys.
   *
   * @var array
   */
  protected $keys = array('positive' => array(), 'negative' => array());

  /**
   * Indicates whether the first pass query requires complex conditions (LIKE).
   *
   * @var boolean.
   */
  protected $simple = TRUE;

  /**
   * Conditions that are used for exact searches.
   *
   * This is always used for the second pass query but not for the first pass,
   * unless $this->simple is FALSE.
   *
   * @var DatabaseCondition
   */
  protected $conditions;

  /**
   * Indicates how many matches for a search query are necessary.
   *
   * @var int
   */
  protected $matches = 0;

  /**
   * Array of search words.
   *
   * These words have to match against {search_index}.word.
   *
   * @var array
   */
  protected $words = array();

  /**
   * Multiplier for the normalized search score.
   *
   * This value is calculated by the first pass query and multiplied with the
   * actual score of a specific word to make sure that the resulting calculated
   * score is between 0 and 1.
   *
   * @var float
   */
  protected $normalize;

  /**
   * Indicates whether the first pass query has been executed.
   *
   * @var boolean
   */
  protected $executedFirstPass = FALSE;

  /**
   * Stores score expressions.
   *
   * @var array
   */
  protected $scores = array();

  /**
   * Stores arguments for score expressions.
   *
   * @var array
   */
  protected $scoresArguments = array();

  /**
   * Total value of all the multipliers.
   *
   * @var array
   */
  protected $multiply = array();

  /**
   * Sets up the search query expression.
   *
   * @param $query
   *   A search query string, which can contain options.
   * @param $module
   *   The search module. This maps to {search_index}.type in the database.
   *
   * @return
   *   The SearchQuery object.
   */
  public function searchExpression($expression, $module) {
    $this->searchExpression = $expression;
    $this->type = $module;

    return $this;
  }

  /**
   * Applies a search option and removes it from the search query string.
   *
   * These options are in the form option:value,value2,value3.
   *
   * @param $option
   *   Name of the option.
   * @param $column
   *   Name of the database column to which the value should be applied.
   *
   * @return
   *   TRUE if a value for that option was found, FALSE if not.
   */
  public function setOption($option, $column) {
    if ($values = search_expression_extract($this->searchExpression, $option)) {
      $or = db_or();
      foreach (explode(',', $values) as $value) {
        $or->condition($column, $value);
      }
      $this->condition($or);
      $this->searchExpression = search_expression_insert($this->searchExpression, $option);
      return TRUE;
    }
    return FALSE;
  }

  /**
   * Parses the search query into SQL conditions.
   *
   * We build two queries that match the dataset bodies.
   */
  protected function parseSearchExpression() {
    // Matchs words optionally prefixed by a dash. A word in this case is
    // something between two spaces, optionally quoted.
    preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' .  $this->searchExpression , $keywords, PREG_SET_ORDER);

    if (count($keywords) ==  0) {
      return;
    }

    // Classify tokens.
    $or = FALSE;
    $warning = '';
    foreach ($keywords as $match) {
      $phrase = FALSE;
      // Strip off phrase quotes.
      if ($match[2]{0} == '"') {
        $match[2] = substr($match[2], 1, -1);
        $phrase = TRUE;
        $this->simple = FALSE;
      }
      // Simplify keyword according to indexing rules and external
      // preprocessors. Use same process as during search indexing, so it
      // will match search index.
      $words = search_simplify($match[2]);
      // Re-explode in case simplification added more words, except when
      // matching a phrase.
      $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
      // Negative matches.
      if ($match[1] == '-') {
        $this->keys['negative'] = array_merge($this->keys['negative'], $words);
      }
      // OR operator: instead of a single keyword, we store an array of all
      // OR'd keywords.
      elseif ($match[2] == 'OR' && count($this->keys['positive'])) {
        $last = array_pop($this->keys['positive']);
        // Starting a new OR?
        if (!is_array($last)) {
          $last = array($last);
        }
        $this->keys['positive'][] = $last;
        $or = TRUE;
        continue;
      }
      // AND operator: implied, so just ignore it.
      elseif ($match[2] == 'AND' || $match[2] == 'and') {
        $warning = $match[2];
        continue;
      }

      // Plain keyword.
      else {
        if ($match[2] == 'or') {
          $warning = $match[2];
        }
        if ($or) {
          // Add to last element (which is an array).
          $this->keys['positive'][count($this->keys['positive']) - 1] = array_merge($this->keys['positive'][count($this->keys['positive']) - 1], $words);
        }
        else {
          $this->keys['positive'] = array_merge($this->keys['positive'], $words);
        }
      }
      $or = FALSE;
    }

    // Convert keywords into SQL statements.
    $this->conditions = db_and();
    $simple_and = FALSE;
    $simple_or = FALSE;
    // Positive matches.
    foreach ($this->keys['positive'] as $key) {
      // Group of ORed terms.
      if (is_array($key) && count($key)) {
        $simple_or = TRUE;
        $any = FALSE;
        $queryor = db_or();
        foreach ($key as $or) {
          list($num_new_scores) = $this->parseWord($or);
          $any |= $num_new_scores;
          $queryor->condition('d.data', "% $or %", 'LIKE');
        }
        if (count($queryor)) {
          $this->conditions->condition($queryor);
          // A group of OR keywords only needs to match once.
          $this->matches += ($any > 0);
        }
      }
      // Single ANDed term.
      else {
        $simple_and = TRUE;
        list($num_new_scores, $num_valid_words) = $this->parseWord($key);
        $this->conditions->condition('d.data', "% $key %", 'LIKE');
        if (!$num_valid_words) {
          $this->simple = FALSE;
        }
        // Each AND keyword needs to match at least once.
        $this->matches += $num_new_scores;
      }
    }
    if ($simple_and && $simple_or) {
      $this->simple = FALSE;
    }
    // Negative matches.
    foreach ($this->keys['negative'] as $key) {
      $this->conditions->condition('d.data', "% $key %", 'NOT LIKE');
      $this->simple = FALSE;
    }

    if ($warning == 'or') {
      drupal_set_message(t('Search for either of the two terms with uppercase <strong>OR</strong>. For example, <strong>cats OR dogs</strong>.'));
    }
  }

  /**
   * Helper function for parseQuery().
   */
  protected function parseWord($word) {
    $num_new_scores = 0;
    $num_valid_words = 0;
    // Determine the scorewords of this word/phrase.
    $split = explode(' ', $word);
    foreach ($split as $s) {
      $num = is_numeric($s);
      if ($num || drupal_strlen($s) >= variable_get('minimum_word_size', 3)) {
        if (!isset($this->words[$s])) {
          $this->words[$s] = $s;
          $num_new_scores++;
        }
        $num_valid_words++;
      }
    }
    // Return matching snippet and number of added words.
    return array($num_new_scores, $num_valid_words);
  }

  /**
   * Executes the first pass query.
   *
   * This can either be done explicitly, so that additional scores and
   * conditions can be applied to the second pass query, or implicitly by
   * addScore() or execute().
   *
   * @return
   *   TRUE if search items exist, FALSE if not.
   */
  public function executeFirstPass() {
    $this->parseSearchExpression();

    if (count($this->words) == 0) {
      form_set_error('keys', format_plural(variable_get('minimum_word_size', 3), 'You must include at least one positive keyword with 1 character or more.', 'You must include at least one positive keyword with @count characters or more.'));
      return FALSE;
    }
    $this->executedFirstPass = TRUE;

    if (!empty($this->words)) {
      $or = db_or();
      foreach ($this->words as $word) {
        $or->condition('i.word', $word);
      }
      $this->condition($or);
    }
    // Build query for keyword normalization.
    $this->join('search_total', 't', 'i.word = t.word');
    $this
      ->condition('i.type', $this->type)
      ->groupBy('i.type')
      ->groupBy('i.sid')
      ->having('COUNT(*) >= :matches', array(':matches' => $this->matches));

    // Clone the query object to do the firstPass query;
    $first = clone $this->query;

    // For complex search queries, add the LIKE conditions to the first pass query.
    if (!$this->simple) {
      $first->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
      $first->condition($this->conditions);
    }

    // Calculate maximum keyword relevance, to normalize it.
    $first->addExpression('SUM(i.score * t.count)', 'calculated_score');
    $this->normalize = $first
      ->range(0, 1)
      ->orderBy('calculated_score', 'DESC')
      ->execute()
      ->fetchField();

    if ($this->normalize) {
      return TRUE;
    }
    return FALSE;
  }

  /**
   * Adds a custom score expression to the search query.
   *
   * Each score expression can optionally use a multiplier, and multiple
   * expressions are combined.
   *
   * @param $score
   *   The score expression.
   * @param $arguments
   *   Custom query arguments for that expression.
   * @param $multiply
   *   If set, the score is multiplied with that value. Search query ensures
   *   that the search scores are still normalized.
   */
  public function addScore($score, $arguments = array(), $multiply = FALSE) {
    if ($multiply) {
      $i = count($this->multiply);
      $score = "CAST(:multiply_$i AS DECIMAL) * COALESCE(( " . $score . "), 0) / CAST(:total_$i AS DECIMAL)";
      $arguments[':multiply_' . $i] = $multiply;
      $this->multiply[] = $multiply;
    }

    $this->scores[] = $score;
    $this->scoresArguments += $arguments;

    return $this;
  }

  /**
   * Executes the search.
   *
   * If not already done, this executes the first pass query. Then the complex
   * conditions are applied to the query including score expressions and
   * ordering.
   *
   * @return
   *   FALSE if the first pass query returned no results, and a database result
   *   set if there were results.
   */
  public function execute()
  {
    if (!$this->executedFirstPass) {
      $this->executeFirstPass();
    }
    if (!$this->normalize) {
      return new DatabaseStatementEmpty();
    }

    // Add conditions to query.
    $this->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
    $this->condition($this->conditions);

    if (empty($this->scores)) {
      // Add default score.
      $this->addScore('i.relevance');
    }

    if (count($this->multiply)) {
      // Add the total multiplicator as many times as requested to maintain
      // normalization as far as possible.
      $i = 0;
      $sum = array_sum($this->multiply);
      foreach ($this->multiply as $total) {
        $this->scoresArguments[':total_' . $i] = $sum;
        $i++;
      }
    }

    // Replace i.relevance pseudo-field with the actual, normalized value.
    $this->scores = str_replace('i.relevance', '(' . (1.0 / $this->normalize) . ' * i.score * t.count)', $this->scores);
    // Convert scores to an expression.
    $this->addExpression('SUM(' . implode(' + ', $this->scores) . ')', 'calculated_score', $this->scoresArguments);

    if (count($this->getOrderBy()) == 0) {
      // Add default order after adding the expression.
      $this->orderBy('calculated_score', 'DESC');
    }

    // Add tag and useful metadata.
    $this
      ->addTag('search_' . $this->type)
      ->addMetaData('normalize', $this->normalize)
      ->fields('i', array('type', 'sid'));

    return $this->query->execute();
  }

  /**
   * Builds the default count query for SearchQuery.
   *
   * Since SearchQuery always uses GROUP BY, we can default to a subquery. We
   * also add the same conditions as execute() because countQuery() is called
   * first.
   */
  public function countQuery() {
    // Clone the inner query.
    $inner = clone $this->query;

    // Add conditions to query.
    $inner->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
    $inner->condition($this->conditions);

    // Remove existing fields and expressions, they are not needed for a count
    // query.
    $fields =& $inner->getFields();
    $fields = array();
    $expressions =& $inner->getExpressions();
    $expressions = array();

    // Add the sid as the only field and count them as a subquery.
    $count = db_select($inner->fields('i', array('sid')), NULL, array('target' => 'slave'));

    // Add the COUNT() expression.
    $count->addExpression('COUNT(*)');

    return $count;
  }
}

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