Possibly bug or incorrect code?

$this->db->query(...) returns an object, not an array with the records from the table.
To fetch the records from the query object, you need to do this:

PHP Code:

$records = $query->result();  //returns an array of objects, each object is a table record
//or 
$records = $query->result_array();  // returns an array of arrays, each sub-array is a table record 


You can use foreach { } to cycle through the records and to get access to the fields inside each record:

PHP Code:

foreach ($records as $record) {
  // ...
}