How to use parameter in function with pagination CodeIgniter?

Question

I have function which takes state name as a parameter and displays all the cities of that specific state. Since list of cities is very long I have used pagination in the same function but when I click on the 'Next' or any other pagination link the function accepts the offset value in the $state variable. The function is

public function load_Page($state){
    $this->load->database();
    $this->load->library('pagination');
    $a = 1;

    $this->db->select("*")->where("userstate" , $a)->where("state" , $state);
    $query0 = $this->db->get("city");

            $this->db->select("*")->where("userstate" , $a)->where("state" , $state);
            $query1 = $this->db->get('city' , 10 , $this->uri->segment(3));
            $config["base_url"] = base_url()."index.php/city/load_Page";
            $total_row = $query0->num_rows();
            $config['page_query_string'] = TRUE;
            $config["total_rows"] = $total_row;
            $config["per_page"] = 10;

            $this->pagination->initialize($config);


            $data["state"] = $state;
            $data["result"] = $query1->result();
            //$data["rows"] = $query1->num_rows();
            $this->load->view('header');
            $this->load->view('city', $data);
            $this->load->view('footer');

}

Is there any other way out to do it or I am going completely wrong?

Answer 1

First of all, when you are paginating, the page number has to come from the URL, and that's always available as a parameter in the controller method. It should default to page 1.

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

class City extends CI_Controller {

    public function load_page( $state, $page = 1 ){

        // I'm going to use an alias for this model
        $this->load->model('example_model', 'model');

        // Use the URL helper for site_url()
        $this->load->helper('url');

        // Set pagination config
        $config['pagination_settings'] = [
            'per_page'          => 10,
            'use_page_numbers'  => TRUE,
            'uri_segment'       => 4, // This is very important!!!
            'base_url'          => site_url('city/load_page/' . $state)
        ];

        // Get the total rows
        $config['pagination_settings']["total_rows"] = $this->model->pagination_count( $state );

        // Load and initialize pagination
        $this->load->library('pagination');
        $this->pagination->initialize($config['pagination_settings']);

        $data = [
            'state' => $state,
            'rows' => $this->model->get_cities( $state, $page, $config['pagination_settings']['per_page'] ),
            'links' => $this->pagination->create_links()
        ];

        // Use data in views or wherever needed ...
        $this->load->view('city', $data);
    }

    /**
     * Create the rows to paginate
     */
    public function setup()
    {
        // I'm going to use an alias for this model
        $this->load->model('example_model', 'model');

        $this->model->setup();
    }

    // -----------------------------------------------------------------------
}

Next, you should move your database queries to a model. You don't need to use transactions for your 2 select type queries.

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

class Example_model extends CI_Model{

    public function __construct()
    {
        parent::__construct();

        $this->load->database();
    }

    public function pagination_count( $state )
    {
        return $this->db->where("state" , $state)
            ->count_all_results('city');
    }

    public function get_cities( $state, $page, $limit )
    {
        $offset = ( $page * $limit ) - $limit;

        $query = $this->db->where("state" , $state)
            ->limit( $limit, $offset )
            ->get('city');

        if( $query->num_rows() > 0 )
            return $query->result();

        return NULL;
    }

    /**
     * Setup for testing
     */
    public function setup()
    {
        $this->load->dbforge();

        $fields = array(
            'id' => array(
                'type' => 'INT',
                'constraint' => 5,
                'unsigned' => TRUE,
                'auto_increment' => TRUE
            ),
            'state' => array(
                'type' => 'VARCHAR',
                'constraint' => '32',
            ),
            'city' => array(
                'type' => 'VARCHAR',
                'constraint' => '32',
            ),
        );
        $this->dbforge->add_field($fields);
        $this->dbforge->add_key('id', TRUE);
        $this->dbforge->create_table('city', TRUE);

        for( $x = 1; $x <= 40; $x++ )
        {
            $this->db->insert('city', array(
                'state' => 'ca',
                'city'  => 'x' . $x
            ));
        }
    }
}

This is the view that I used:

<?php

echo '<h1>' . $state . '</h1>';

echo $links . '<br /><br />';

foreach( $rows as $row )
{
    echo $row->city . '<br />';
}

To set up the database for testing, I went to:

http://localhost/index.php/city/setup

Then to check out that the pagination works, I went to:

http://localhost/index.php/city/load_page/ca

It should work for you, as this code is now fully tested.

UPDATE --------------------

If you want to add more parameters to your pagination, do it with query strings. You will need to set the pagination config with this extra setting:

$config['pagination_settings']['reuse_query_string'] = TRUE;

That means the config would look like this:

$config['pagination_settings'] = [
    'per_page'           => 10,
    'use_page_numbers'   => TRUE,
    'uri_segment'        => 4, // This is very important!!!
    'base_url'           => site_url('city/load_page/' . $state),
    'reuse_query_string' => TRUE
];

And then you create the link to the first page with your params:

http://localhost/index.php/city/load_page/ca?a=1&b=2&c=3

And because of the reuse_query_strings being set to TRUE, that means that ?a=1&b=2&c=3 would all be attached to the pagination links.