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.
$table: The table this field is attached to. If NULL, it is assumed this will be a formula; otherwise, ensure_table is used to make sure the table exists.
$field: The name of the field to add. This may be a real field or a formula.
$alias: The alias to create. If not specified, the alias will be $table_$field unless $table is NULL. When adding formulae, it is recommended that an alias be used.
$params: An array of parameters additional to the field that will control items such as aggregation functions and DISTINCT.
$name The name that this field can be referred to as. Usually this is the alias.
public function addField($table, $field, $alias = '', $params = array()) {
// We check for this specifically because it gets a special alias.
if ($table == $this->view->storage
->get('base_table') && $field == $this->view->storage
->get('base_field') && empty($alias)) {
$alias = $this->view->storage
->get('base_field');
}
if ($table && empty($this->table_queue[$table])) {
$this
->ensure_table($table);
}
if (!$alias && $table) {
$alias = $table . '_' . $field;
}
// Make sure an alias is assigned
$alias = $alias ? $alias : $field;
// PostgreSQL truncates aliases to 63 characters: http://drupal.org/node/571548
// We limit the length of the original alias up to 60 characters
// to get a unique alias later if its have duplicates
$alias = strtolower(substr($alias, 0, 60));
// Create a field info array.
$field_info = array(
'field' => $field,
'table' => $table,
'alias' => $alias,
) + $params;
// Test to see if the field is actually the same or not. Due to
// differing parameters changing the aggregation function, we need
// to do some automatic alias collision detection:
$base = $alias;
$counter = 0;
while (!empty($this->fields[$alias]) && $this->fields[$alias] != $field_info) {
$field_info['alias'] = $alias = $base . '_' . ++$counter;
}
if (empty($this->fields[$alias])) {
$this->fields[$alias] = $field_info;
}
// Keep track of all aliases used.
$this->field_aliases[$table][$field] = $alias;
return $alias;
}