public function SelectQuery::preExecute

Generic preparation and validation for a SELECT query.

Return value

TRUE if the validation was successful, FALSE if not.

Overrides SelectQueryInterface::preExecute

File

includes/database/select.inc, line 1252

Class

SelectQuery

Query builder for SELECT statements.

Code

public function preExecute(SelectQueryInterface $query = NULL) {

  // If no query object is passed in, use $this.
  if (!isset($query)) {
    $query = $this;
  }

  // Only execute this once.
  if ($query
    ->isPrepared()) {
    return TRUE;
  }

  // Modules may alter all queries or only those having a particular tag.
  if (isset($this->alterTags)) {

    // Many contrib modules assume that query tags used for access-checking
    // purposes follow the pattern $entity_type . '_access'. But this is
    // not the case for taxonomy terms, since core used to add term_access
    // instead of taxonomy_term_access to its queries. Provide backwards
    // compatibility by adding both tags here instead of attempting to fix
    // all contrib modules in a coordinated effort.
    // TODO:
    // - Extract this mechanism into a hook as part of a public (non-security)
    //   issue.
    // - Emit E_USER_DEPRECATED if term_access is used.
    //   https://www.drupal.org/node/2575081
    $term_access_tags = array(
      'term_access' => 1,
      'taxonomy_term_access' => 1,
    );
    if (array_intersect_key($this->alterTags, $term_access_tags)) {
      $this->alterTags += $term_access_tags;
    }
    $hooks = array(
      'query',
    );
    foreach ($this->alterTags as $tag => $value) {
      $hooks[] = 'query_' . $tag;
    }
    drupal_alter($hooks, $query);
  }
  $this->prepared = TRUE;

  // Now also prepare any sub-queries.
  foreach ($this->tables as $table) {
    if ($table['table'] instanceof SelectQueryInterface) {
      $table['table']
        ->preExecute();
    }
  }
  foreach ($this->union as $union) {
    $union['query']
      ->preExecute();
  }
  return $this->prepared;
}