CodeIgniter 3 Paging Library

Paging.php

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

use ChangeCase\ChangeCase;

class Paging {

    private $ci;
    
    private $qb;
    private $current_page;
    private $per_page;
    private $total_record;
    private $total_page;

    private $default_orders = [];
    private $default_filters = [];
    private $column_aliases = [];

    public function __construct()
    {
        $this->ci =& get_instance();
        $this->ci->load->database();
        $this->ci->load->helper('url');
    }

    public function set_default_orders($orders = [])
    {
        $this->default_orders = $orders;
        return $this;
    }

    public function set_default_filters($filters = [])
    {
        $this->default_filters = $filters;
        return $this;
    }

    /**
     * Mapping the column aliases for querying
     * Used for used defined filter columns
     * 
     * Formatted as: alias => field name
     */
    public function set_column_aliases($column_aliases)
    {
        $this->column_aliases = $column_aliases;
        return $this;
    }

    private function filter()
    {
        $q = $this->ci->input->get('q');
        $filter_cols = $this->ci->input->get('filter_cols');

        $filters = [];
        
        if (!empty($q)) {
            foreach ($filter_cols as $col) {
                // We get camel case from the client
                // Let's change it to snake case
                $col_snake = ChangeCase::snake($col);

                if (array_key_exists($col_snake, $this->column_aliases)) {
                    if (is_array($this->column_aliases[$col_snake])) {
                        foreach ($this->column_aliases[$col_snake] as $field) {
                            $filters[] = $field." LIKE '%$q%'";
                        }
                    } else {
                        $filters[] = $this->column_aliases[$col_snake]." LIKE '%$q%'";
                    }
                } else {
                    $filters[] = $col_snake." LIKE '%$q%'";
                }
            }
        }
        
        $filter_search = !empty($filters) ? '('.implode(' OR ', $filters).')' : NULL;
        $default_filter = !empty($this->default_filters) ? implode(' AND ', $this->default_filters) : NULL;

        $filter = $filter_search ?? '';
        
        if (!empty($default_filter)) {
            $filter .= !empty($filter_search) ? ' AND '.$default_filter : $default_filter;
        }

        if (!empty($filter)) {
            $this->qb->where($filter);
        }

        $this->total_record = $this->qb->count_all_results('', FALSE);
        $this->total_page = ceil($this->total_record / $this->per_page);
    }

    private function order()
    {
        $sorts = $this->ci->input->get('sorts') ?? [];

        $orders = [];
        
        foreach ($sorts as $sort) {
            $order = json_decode($sort);
            $orders[$order->prop] = $order->prop.' '.($order->order == 'ascending' ? 'ASC' : 'DESC');
        }

        foreach ($this->default_orders as $key => $val) {
            if (!isset($orders[$key])) {
                $orders[$key] = $key.' '.$val; // coded already with ASC or DESC
            }
        }

        if (!empty($orders)) {
            $this->qb->order_by(implode(', ', $orders));
        }
    }

    private function limit()
    {
        $offset = ($this->current_page - 1) * $this->per_page;
        $this->qb->limit($this->per_page, $offset);
    }

    /**
     * Generate the result
     * @param CI_DB_query_builder $qb The query builder
     * @return object
     */
    public function generate($qb)
    {
        $this->qb = $qb;

        $this->current_page = $this->ci->input->get('page') ?? 1;
        $this->per_page = $this->ci->input->get('per_page') ?? 10;

        $this->filter();
        $this->order();
        $this->limit();

        $results = $this->qb->get()
                            ->result();

        return (object) [
            'data' => $results,
            'paging' => (object) [
                'current_page' => intval($this->current_page),
                'per_page' => intval($this->per_page),
                'total_page' => $this->total_page,
                'total_record' => $this->total_record,
            ]
        ];
    }

    /**
     * Get formatted data for empty result
     */
    public function empty_result()
    {
        return (object) [
            'data' => [],
            'paging' => (object) [
                'current_page' => 1,
                'per_page' => 10,
                'total_page' => 0,
                'total_record' => 0,
            ]
        ];
    }
}