Codeigniter 3 blog application: overwriting default “static” variable with a “dynamic

I am working on a blog application in Codeigniter 3.1.8.

I have a model with "static" data like the website's title, the contact email address, etc:

Code:

class Static_model extends CI_Model {
   public function get_static_data() {
       $data['site_title'] = "My Blog";
       $data['tagline'] = "A simple blog application made with Codeigniter 3";
       $data['company_name'] = "My Company";
       $data['company_email'] = "[email protected]";
       return $data;
   }
}

In my Posts Controller, I have tried to flow the DRY principle this way:

Code:

class Posts extends CI_Controller {

   public function __construct()
   {
     parent::__construct();
     // Load static data
     $this->load->model('Static_model');
     $data = $this->Static_model->get_static_data();
     // Load Header
     $this->load->view('partials/header', $data);
   }

   public function index()
   {
       $this->load->model('Posts_model');
       $data['posts'] = $this->Posts_model->get_posts();
       $this->load->view('posts', $data);
       $this->load->view('partials/footer');
   }

   public function post($id)
   {
       $this->load->model('Posts_model');
       $data['post'] = $this->Posts_model->get_post($id);

       if (!empty($data['post'])) {
           // Overwrite the default tagline with the post title
           $data['tagline'] = $data['post']->title;
       } else {
           $data['tagline'] = "Page not found";
           show_404();
       }

       $this->load->view('post', $data);
       $this->load->view('partials/footer');
   }

}

See details of how I came about writing the code above in this topic on stackoverflow.com

The problem with the above code is that the line 

Code:

$data['tagline'] = $data['post']->title;

 does no longer overwrite the static tagline 

Code:

$data['tagline'] = "A simple blog application made with Codeigniter 3";

 with the post title. It did overwrite it when the controller look like this:
class Posts extends CI_Controller {

Code:

   public function index()
   {
       $this->load->model('Static_model');
       $data = $this->Static_model->get_static_data();

       $this->load->model('Posts_model');
       $data['posts'] = $this->Posts_model->get_posts();

       $this->load->view('partials/header', $data);
       $this->load->view('posts');
       $this->load->view('partials/footer');
   }

   public function post($id) {
       $this->load->model('Static_model');
       $data = $this->Static_model->get_static_data();

       $this->load->model('Posts_model');
       $data['post'] = $this->Posts_model->get_post($id);

       // Overwrite the default tagline with the post title
       $data['tagline'] = $data['post']->title;

       $this->load->view('partials/header', $data);
       $this->load->view('post');
       $this->load->view('partials/footer');
   }

}

Bot this old version of it is goes against the DRY principle.


How can I do the desired overwrite without breaking the "DRY commandment"?