Codeigniter 3 blog: how can I use the pagination f

I am working on a basic blog application in Codeigniter 3.1.8. The posts are paginated. The application uses a pagination.php configuration file.

There is a search box for searching posts. I wish to paginate the search results and, since the methods index() and search() are in the same Posts controller, I am looking for a way avoid code redundancy by using the pagination inside index() for the search results too.

In the posts controller I have:

class Posts extends CI_Controller {
  public function __construct() {
    parent::__construct();
    $this->load->model('Static_model');
    $this->load->model('Posts_model');
    $this->load->model('Categories_model');
    $this->load->model('Comments_model');
  }

  public function index() {
    //load and configure pagination 
    $this->load->library('pagination');
    $config['base_url'] = base_url("/posts");
    $config['query_string_segment'] = 'page';
    $config['total_rows'] = $this->Posts_model->get_num_rows();
    $config['per_page'] = 12;
    if (!isset($_GET[$config['query_string_segment']]) || $_GET[$config['query_string_segment']] < 1) {
      $_GET[$config['query_string_segment']] = 1;
    }
    $limit = $config['per_page'];
    $offset = ($this->input->get($config['query_string_segment']) - 1) * $limit;
    $this->pagination->initialize($config);
    $data = $this->Static_model->get_static_data();
    $data['categories'] = $this->Categories_model->get_categories();
    $data['posts'] = $this->Posts_model->get_posts($limit, $offset);
    $this->load->view('partials/header', $data);
    $this->load->view('posts');
    $this->load->view('partials/footer');
  }

  public function search() {
    $this->form_validation->set_rules('search', 'Search term', 'required|trim|min_length[3]');
    $this->form_validation->set_error_delimiters('<p class = "error search-error"> ', ' </p>
      ');
      // If search fails
      if ($this->form_validation->run() === FALSE) {
        return $this->index();
      } else {
        $expression = $this->input->post('search');
        $data = $this->Static_model->get_static_data();
        $data['categories'] = $this->Categories_model->get_categories();
        $data['posts'] = $this->Posts_model->search($expression, $limit, $offset);
        $data['expression'] = $expression;
        $this->load->view('partials/header', $data);
        $this->load->view('search');
        $this->load->view('partials/footer');
      }
    }
  }

The Posts_model model has the code for both the posts list and the search results:

public function get_posts($limit, $offset) {
    $this->db->order_by('id', 'DESC');
    $query = $this->db->get('posts', $limit, $offset);
    return $query->result();
}

public function search_count($expression) {
    $query = $this->db->like('title', $expression)
                  ->or_like('description', $expression)
                  ->or_like('content', $expression);
    $query = $this->db->get('posts');
    return $query->num_rows();  
}

public function search($expression, $limit, $offset) {
    $query = $this->db->like('title', $expression)
              ->or_like('description', $expression)
              ->or_like('content', $expression);
    $this->db->order_by('posts.id', 'DESC');
    $query = $this->db->get('posts', $limit, $offset);
    return $query->result();
}

To be clear, I want to avoid copying this into the search() method:

$this->load->library('pagination');
    $config['query_string_segment'] = 'page';
    $config['total_rows'] = $this->Posts_model->get_num_rows();
    $config['per_page'] = 12;
    if (!isset($_GET[$config['query_string_segment']]) || $_GET[$config['query_string_segment']] < 1) {
      $_GET[$config['query_string_segment']] = 1;
    }
    $limit = $config['per_page'];
    $offset = ($this->input->get($config['query_string_segment']) - 1) * $limit;
    $this->pagination->initialize($config);

I got stuck in my attempt to borrow the pagination from index() to search().

What is missing?

Try something like this:
- create a private method in controller and move paginator initialization code here
- call private method inside index() and search()

class Posts extends CI_Controller {
  public function __construct() {
    parent::__construct();
    $this->load->model('Static_model');
    $this->load->model('Posts_model');
    $this->load->model('Categories_model');
    $this->load->model('Comments_model');
  }

  private function _initPagination($path, $totalRows) {
    //load and configure pagination 
    $this->load->library('pagination');
    $config['base_url'] = base_url($path);
    $config['query_string_segment'] = 'page';
    //pass $totalRows param to pagination config
    $config['total_rows'] = $totalRows;
    $config['per_page'] = 12;
    if (!isset($_GET[$config['query_string_segment']]) || $_GET[$config['query_string_segment']] < 1) {
      $_GET[$config['query_string_segment']] = 1;
    }
    $this->pagination->initialize($config);

    $limit = $config['per_page'];
    $offset = ($this->input->get($config['query_string_segment']) - 1) * $limit;

    return ['limit' => $limit, 'offset' => $offset];
  }

  public function index() {
    //call initialization method
    $config = $this->_initPagination("/posts", $this->Posts_model->get_num_rows());

    $data = $this->Static_model->get_static_data();
    $data['categories'] = $this->Categories_model->get_categories();

    //use limit and offset returned by _initPaginator method
    $data['posts'] = $this->Posts_model->get_posts($config['limit'], $config['offset']);
    $this->load->view('partials/header', $data);
    $this->load->view('posts');
    $this->load->view('partials/footer');
  }

  public function search() {
    $this->form_validation->set_rules('search', 'Search term', 'required|trim|min_length[3]');
    $this->form_validation->set_error_delimiters('<p class = "error search-error"> ', ' </p>
      ');
      // If search fails
      if ($this->form_validation->run() === FALSE) {
        return $this->index();
      } else {
        $expression = $this->input->post('search');
        //call initialization method
        $config = $this->_initPagination("/search", $this->Posts_model->search_count($expression));
        $data = $this->Static_model->get_static_data();
        $data['categories'] = $this->Categories_model->get_categories();

        //use limit and offset returned by _initPaginator method
        $data['posts'] = $this->Posts_model->search($expression, $config['limit'], $config['offset']);
        $data['expression'] = $expression;
        $this->load->view('partials/header', $data);
        $this->load->view('search');
        $this->load->view('partials/footer');
      }
    }
  }