Ensure a table exists in the queue; if it already exists it won't do anything, but if it doesn't it will add the table queue. It will ensure a path leads back to the relationship table.

Parameters

string $table: The unaliased name of the table to ensure.

string $relationship: The relationship to ensure the table links to. Each relationship will get a unique instance of the table being added. If not specified, will be the primary table.

views_join $join: A views_join object (or derived object) to join the alias in.

Return value

string The alias used to refer to this specific table, or NULL if the table cannot be ensured.

3 calls to views_plugin_query_default::ensure_table()

views_plugin_query_default::add_field in plugins/views_plugin_query_default.inc

Add a field to the query table, possibly with an alias. This will automatically call ensure_table to make sure the required table exists, *unless* $table is unset.

views_plugin_query_default::add_orderby in plugins/views_plugin_query_default.inc

Add an ORDER BY clause to the query.

views_plugin_query_default::adjust_join in plugins/views_plugin_query_default.inc

Fix a join to adhere to the proper relationship.

File

plugins/views_plugin_query_default.inc, line 571

Class

views_plugin_query_default

Object used to create a SELECT query.

Code

public function ensure_table($table, $relationship = NULL, $join = NULL) {
    // Ensure a relationship.
    if (empty($relationship)) {
        $relationship = $this->base_table;
    }
    // If the relationship is the primary table, this actually be a relationship
    // link back from an alias. We store all aliases along with the primary
    // table to detect this state, because eventually it'll hit a table we
    // already have and that's when we want to stop.
    if ($relationship == $this->base_table && !empty($this->tables[$relationship][$table])) {
        return $this->tables[$relationship][$table]['alias'];
    }
    if (!array_key_exists($relationship, $this->relationships)) {
        return FALSE;
    }
    if ($table == $this->relationships[$relationship]['base']) {
        return $relationship;
    }
    // If we do not have join info, fetch it.
    if (!isset($join)) {
        $join = $this->get_join_data($table, $this->relationships[$relationship]['base']);
    }
    // If it can't be fetched, this won't work.
    if (empty($join)) {
        return;
    }
    // Adjust this join for the relationship, which will ensure that the 'base'
    // table it links to is correct. Tables adjoined to a relationship
    // join to a link point, not the base table.
    $join = $this->adjust_join($join, $relationship);
    if ($this->ensure_path($table, $relationship, $join)) {
        // Attempt to eliminate redundant joins.  If this table's relationship
        // and join exactly matches an existing table's relationship and join, we
        // do not have to join to it again; just return the existing table's
        // alias.
        // @see http://groups.drupal.org/node/11288
        //
        // This can be done safely here but not lower down in queue_table(),
        // because queue_table() is also used by add_table() which requires the
        // ability to intentionally add the same table with the same join
        // multiple times.  For example, a view that filters on 3 taxonomy terms
        // using AND needs to join taxonomy_term_data 3 times with the same join.
        // scan through the table queue to see if a matching join and
        // relationship exists.  If so, use it instead of this join.
        // @todo Scanning through $this->table_queue results in an O(N^2)
        // algorithm, and this code runs every time the view is instantiated
        // (Views 2 does not currently cache queries). There are a couple
        // possible "improvements" but we should do some performance testing
        // before picking one.
        foreach ($this->table_queue as $queued_table) {
            // In PHP 4 and 5, the == operation returns TRUE for two objects if
            // they are instances of the same class and have the same attributes
            // and values.
            if ($queued_table['relationship'] == $relationship && $queued_table['join'] == $join) {
                return $queued_table['alias'];
            }
        }
        return $this->queue_table($table, $relationship, $join);
    }
}