Method setup

/**
 * Method to attach a Form object to the field.
 *
 * @param   \SimpleXMLElement  $element  The SimpleXMLElement object representing the `<field>` tag for the form field object.
 * @param   mixed              $value    The form field value to validate.
 * @param   string             $group    The field name group control value. This acts as an array container for the field.
 *                                       For example if the field has name="foo" and the group value is set to "bar" then the
 *                                       full field name would end up being "bar[foo]".
 *
 * @return  boolean  True on success.
 *
 * @see     FormField::setup()
 * @since   3.2
 */
public function setup(\SimpleXMLElement $element, $value, $group = null)
{
    $return = parent::setup($element, $value, $group);
    if ($return) {
        // Check if its using the old way
        $this->query = (string) $this->element['query'];
        if (empty($this->query)) {
            // Get the query from the form
            $query = array();
            $defaults = array();
            $sql_select = (string) $this->element['sql_select'];
            $sql_from = (string) $this->element['sql_from'];
            if ($sql_select && $sql_from) {
                $query['select'] = $sql_select;
                $query['from'] = $sql_from;
                $query['join'] = (string) $this->element['sql_join'];
                $query['where'] = (string) $this->element['sql_where'];
                $query['group'] = (string) $this->element['sql_group'];
                $query['order'] = (string) $this->element['sql_order'];
                // Get the filters
                $filters = isset($this->element['sql_filter']) ? explode(',', $this->element['sql_filter']) : '';
                // Get the default value for query if empty
                if (\is_array($filters)) {
                    foreach ($filters as $filter) {
                        $name = "sql_default_{$filter}";
                        $attrib = (string) $this->element[$name];
                        if (!empty($attrib)) {
                            $defaults[$filter] = $attrib;
                        }
                    }
                }
                // Process the query
                $this->query = $this->processQuery($query, $filters, $defaults);
            }
        }
        $this->keyField = (string) $this->element['key_field'] ?: 'value';
        $this->valueField = (string) $this->element['value_field'] ?: (string) $this->element['name'];
        $this->translate = (string) $this->element['translate'] ?: false;
        $this->header = (string) $this->element['header'] ?: false;
    }
    return $return;
}