rest api codeigniter result missing column

i'm having trouble with rest API result in Codeigniter 2.2.6



i want to select 2 (full_name, username) column in table participant, but in result full_name column is missing

here is screenshot when i try to SELECT in POSTMAN









here my script for select

Code:

function select_post(){
    if(!$this->post('table')){
        $this->response('no table'); return 0;
    }
    if($this->post('table')=='user'){
    $pos1=false;
    $pos2=false;
    if($this->post('where') ){
        $pos1 = stripos($this->post('where'),'password');
    }
    if($this->post('select')){
        $pos2 = stripos($this->post('select'),'password');
    }
    if($pos1 !== false || $pos2 !== false){
        $this->response('select password is prohibited');return 0;
    }
}
if($this->post('join')&&$this->post('on'))
    $this->db->join($this->post('join'),$this->post('on'));
    if($this->post('table')=='user'){
        if($this->post('where')) {
            $this->db->where($this->post('where').'AND role = 1');
        } else {
            $this->db->where('role = 1');
        } 
    } else {
        if($this->post('where')) $this->db->where($this->post('where'));
    }
 
 
if($this->post('select'))
    $this->db->select($this->post('select'));
    if($this->post('limit')){
        $this->db->limit($this->post('limit'));
    }else{
        $this->db->limit(10);
    }
   
if($this->post('limit')&&$this->post('offset'))
    $this->db->limit($this->post('limit'),$this->post('offset'));
    if($this->post('order'))
        $this->db->order_by($this->post('order'));
        $query = $this->db->get($this->post('table'));
        $result=$query->result();
        $txtOut="[";
        foreach($result as $row){
            $txtOut.="{";
            $row=(array)$row;
            foreach($row as $col){
                if(key($row)!=='password'&&key($row)!=='key'){
                    $txtOut.='"'.key($row).'"="'.$col.'",';
                }
                next($row);
            }
            $txtOut=rtrim($txtOut,",");
            $txtOut.="},";
        }
        $txtOut=rtrim($txtOut, ",");
        $this->logging('select',json_encode($_POST),$txtOut."]");
        echo $txtOut."]";
}

Any ideas where i do wrong ?