CPAN::Groonga

      user.name,
      user.username,
      (
        select
          json_group_array(item)
        from (
          select json_object(
            'id',        items.id,
            'title',     i

r.username=?
  SQL
  return $self
    ->sqlite
    ->db
    ->query($sql, $username)
    ->expand(json => 'items')
    ->hash;
}

sub all_users {
  my $self = shift;
  return $self
    ->sqlite
    ->