Query::addSort

protected Query::addSort()

protected function addSort() {
  if ($this->count) {
    $this->sort = array();
  }
  // Gather the SQL field aliases first to make sure every field table
  // necessary is added. This might change whether the query is simple or
  // not. See below for more on simple queries.
  $sort = array();
  if ($this->sort) {
    foreach ($this->sort as $key => $data) {
      $sort[$key] = $this->getSqlField($data['field'], $data['langcode']);
    }
  }
  $simple_query = $this->isSimpleQuery();
  // If the query is set up for paging either via pager or by range or a
  // count is requested, then the correct amount of rows returned is
  // important. If the entity has a data table or multiple value fields are
  // involved then each revision might appear in several rows and this needs
  // a significantly more complex query.
  if (!$simple_query) {
    // First, GROUP BY revision id (if it has been added) and entity id.
    // Now each group contains a single revision of an entity.
    foreach ($this->sqlFields as $field) {
      $group_by = "$field [0].$field [1]";
      $this->sqlGroupBy[$group_by] = $group_by;
    }
  }
  // Now we know whether this is a simple query or not, actually do the
  // sorting.
  foreach ($sort as $key => $sql_alias) {
    $direction = $this->sort[$key]['direction'];
    if ($simple_query || isset($this->sqlGroupBy[$sql_alias])) {
      // Simple queries, and the grouped columns of complicated queries
      // can be ordered normally, without the aggregation function.
      $this->sqlQuery->orderBy($sql_alias, $direction);
      if (!isset($this->sqlFields[$sql_alias])) {
        $this->sqlFields[$sql_alias] = explode('.', $sql_alias);
      }
    }
    else {
      // Order based on the smallest element of each group if the
      // direction is ascending, or on the largest element of each group
      // if the direction is descending.
      $function = $direction == 'ASC' ? 'min' : 'max';
      $expression = "$function($sql_alias)";
      $expression_alias = $this->sqlQuery->addExpression($expression);
      $this->sqlQuery->orderBy($expression_alias, $direction);
    }
  }
  return $this;
}