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;
}