Mdl WarrantyCard

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class Warranty_card_model extends CI_Model
{
    var $table  = 'pelunasan';
    var $id     = 'id_pelunasan';

    var $column = array(
        'no_nota_pelunasan', 'nota_spk', 'nama_customer', 'no_hp', 'nama_produk', 'valid_until'
    );

    private function _get_datatables_query()
    {
        $this->db->select('
            produk.nama_produk,
            spk.id_spk, spk.nota_spk, spk.nama_customer, spk.no_hp,
            spk_detail.spk_valid_until as valid_until,
            pelunasan.id_pelunasan, pelunasan.no_nota_pelunasan, pelunasan.tgl_pelunasan,
            pelunasan_detail.pelunasan_valid_until as valid_until
        ');

        $this->db->from($this->table); // pelunasan

        $this->db->join('spk', 'pelunasan.pelunasan_nota_spk = spk.id_spk');

        $this->db->join(
            "(SELECT spk_id, produk_id, spk_valid_until, spk_maintenance_notes FROM spk_detail
                UNION ALL
                SELECT pelunasan_id, produk_id, pelunasan_valid_until, pelunasan_maintenance_notes FROM pelunasan_detail
                INNER JOIN pelunasan ON pelunasan_detail.pelunasan_id = pelunasan.id_pelunasan
                ) spk_detail",
            'spk.id_spk = spk_detail.spk_id'
        );

        $this->db->join('produk', 'spk_detail.produk_id = produk.id_produk');

        $this->db->where('pelunasan.is_delete', 0);
        $this->db->where('spk.is_delete', 0);

        $i = 0;

        foreach ($this->column as $item)
        {
            if ($_POST['search']['value']) // if datatable send POST for search
            {
                if ($i === 0) // first loop
                {
                    $this->db->group_start();
                    $this->db->like($item, $_POST['search']['value']);
                } else {
                    $this->db->or_like($item, $_POST['search']['value']);
                }

                if (count($this->column) - 1 == $i)
                    $this->db->group_end(); //close bracket
            }
            $column[$i] = $item; // set column array variable to order processing
            $i++;
        }

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

    public function get_datatables()
    {
        $this->_get_datatables_query();

        if ($_POST['length'] != -1)
            $this->db->limit($_POST['length'], $_POST['start']);

        $query = $this->db->get();

        return $query->result();
    }

    public function count_filtered()
    {
        $this->_get_datatables_query();

        $query = $this->db->get();

        return $query->num_rows();
    }

    public function count_all()
    {
        $this->_get_datatables_query();

        return $this->db->count_all_results();
    }