CodeIgniter - Grouping where clause - sql

Question

I have this following query for CodeIgniter:
$q = $this->db->where('(message_from="'.$user_id.'" AND message_to="'.$this->auth_model->userdata['user_id'].'")')
->or_where('(message_from="'.$this->auth_model->userdata['user_id'].'" AND message_to="'.$user_id.'")')
->get('messages');
I want to write this query with completely active record.
I have tried something like this:
$from_where = array('message_from'=>$user_id, 'message_to'=>$this->auth_model->userdata['user_id']);
$to_where = array('message_from'=>$this->auth_model->userdata['user_id'],'message_to'=>$user_id);
$q = $this->db->where($from_where)
->or_where($to_where)
->get('messages');
die($this->db->last_query());
The above code produces this query:
SELECT * FROM (`messages`) WHERE `message_from` = '2' AND `message_to` = '1' OR `message_from` = '1' OR `message_to` = '2'
But this is what I want to produce:
SELECT * FROM (`messages`) WHERE (message_from="2" AND message_to="1") OR (message_from="1" AND message_to="2")
There are similar questions here and here, but thosedid not provide a real solution for me.
How's this possible, If not via core libraries, is there an extension which allows writing such queries?
Thanks,

Answer 1

You can use sub query way of codeigniter to do this for this purpose you will have to hack codeigniter. like this
Go to system/database/DB_active_rec.php Remove public or protected keyword from these functions
public function _compile_select($select_override = FALSE)
public function _reset_select()
Now subquery writing in available And now here is your query with active record
$this->db->where('message_from','2');
$this->db->where('message_to','1');
$subQuery1 = $this->db->_compile_select();
$this->db->_reset_select();
$this->db->where('message_from','1');
$this->db->where('message_to','2');
$subQuery2 = $this->db->_compile_select();
$this->db->_reset_select();
$this->db->select('*');
$this->db->where("$subQuery1");
$this->db->or_where("$subQuery2");
$this->db->get('messages');
Look at this answer of mine. This shows how to use sub queries. This will help
Using Mysql WHERE IN clause in codeigniter
EDITES
Yes i have done it
Rewrite the query this way exactly you want
$this->db->where('message_from','2');
$this->db->where('message_to','1');
$subQuery1 = $this->db->_compile_select(TRUE);
$this->db->_reset_select();
$this->db->where('message_from','1');
$this->db->where('message_to','2');
$subQuery2 = $this->db->_compile_select(TRUE);
$this->db->_reset_select();
$this->db->select('*');
$this->db->where("($subQuery1)");
$this->db->or_where("($subQuery2)");
$this->db->get('messages');
Compile select is with true parameter. Will not produce select clause. This will produce
SELECT * FROM (`messages`) WHERE (`message_from` = '2' AND `message_to` = '1') OR (`message_from` = '1' AND `message_to` = '2')