DATATABLES CODEIGNITER

function load_grid() {
      table = $('#table_grid').DataTable({
        "scrollX": true,
        "processing": true, //Feature control the processing indicator.
        "serverSide": true, //Feature control DataTables' server-side processing mode.
        // Load data for the table's content from an Ajax source
        "ajax": {
            "url": "<?php echo base_url().'Position/ajax_list'?>",
            "type": "POST"
        },
        //Set column definition initialisation properties.
        "columnDefs": [
          {
            "targets": [ -1 ], //last column
            "orderable": false, //set not orderable
            // "className":'mdl-data-table__cell--non-numeric'
          },
        ],

      });
    }
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----------------------------CONTROLLER-----------------------------------------------
public function ajax_list()
    {
    $btn = '';
        $list = $this->m_position->get_datatables();
        $data = array();
        $no = $_POST['start'];
        foreach ($list as $position) {
            $no++;
            $row = array();
            $row[] = $no;
      $row[] = $position->div_code;
            $row[] = $position->position_code;
            $row[] = $position->position_desc;
      $row[] = $position->is_active;
      $row[] = '<a class="btn btn-sm btn-info1" href="javascript:void()" title="Edit" onclick="edit_position('."'".$position->pid."'".')"><i class="glyphicon glyphicon-pencil"></i> Edit</a>
                  <a class="btn btn-sm btn-danger1" href="javascript:void()" title="Hapus" onclick="delete_position('."'".$position->pid."'".')"><i class="glyphicon glyphicon-trash"></i> Delete</a>';

            $data[] = $row;
        }

        $output = array(
                        "draw" => $_POST['draw'],
                        "recordsTotal" => $this->m_position->count_all(),
                        "recordsFiltered" => $this->m_position->count_filtered(),
                        "data" => $data,
                );
        //output to json format
        echo json_encode($output);
    }
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-------------------------MODEL---------------------------------------------------
private function _get_datatables_query()
    {

        $this->db2->from($this->table);

        $i = 0;

        foreach ($this->column as $item)
        {
            if($_POST['search']['value'])
                ($i===0) ? $this->db2->like($item, $_POST['search']['value']) : $this->db2->or_like($item, $_POST['search']['value']);
            $column[$i] = $item;
            $i++;
        }

        if(isset($_POST['order']))
        {
            $this->db2->order_by($column[$_POST['order']['0']['column']], $_POST['order']['0']['dir']);
        }
        else if(isset($this->order))
        {
            $order = $this->order;
            $this->db2->order_by(key($order), $order[key($order)]);
        }
    }

    function get_datatables()
    {
        $this->_get_datatables_query();
        if($_POST['length'] != -1)
        $this->db2->limit($_POST['length'], $_POST['start']);
        $query = $this->db2->get();
        return $query->result();
    }

    function count_filtered()
    {
        $this->_get_datatables_query();
        $query = $this->db2->get();
        return $query->num_rows();
    }

    public function count_all()
    {
        $this->db2->from($this->table);
        return $this->db2->count_all_results();
    }