dropdown li in codeigniter not fetching proper values from database using id - php

Question

I have a site with a dropdown menu that shows city names and after clicking a particular city it redirects to another page that shows the city details.
My problem is that in this page the menu is showing only the current single city, but should show all of them.
here is the image showing header:
after clicking particular city this is how header is looking:
Header view code:
<ul class="dropdown-menu" role="menu">
<?php foreach ($race_details as $city) {?>
<li>
<a class="dropdown-item <?= ($this->uri->segment(2) == 'id') ? 'active' : ''; ?>" href="<?php echo base_url('city/'. $city->id); ?>">
<?= $city->location ?>
</a>
</li>
<?php
}
?>
</ul>
Controller code:
public function city() {
$data['site'] = $this->Site_model->get_site_details();
$data['page_title'] = $data['site']->site_title;
$city_id = $this->uri->segment(2);
if($city_id){
$data['race_details'] = $this->Site_model->get_race_details_by_city($city_id);
$this->load->view('city_page', $data);
}
}
Modal code:
public function get_race_details_by_city($city_id='') {
$this->db->select('*');
$this->db->where('id', $city_id);
$query = $this->db->get('race_details');
return $query->result();
}

Answer 1

Whenever you need dropdown of all the cities (Home page, Header page) you can use all_cities_list() function, Now whenever you need race details by city you can call get_race_details_by_city() function by passing city id in it so both will work for you
public function all_cities_list() {
$this->db->select('*');
$query = $this->db->get('cities');
return $query->result();
}
public function get_race_details_by_city($city_id='') {
$this->db->select('*');
$this->db->where('id', $city_id);
$query = $this->db->get('race_details');
return $query->result();
}

Answer 2

Using two header for city options it's not valid solution. You can also use below alternate solutions.
Always use all_cities_list() function for get list of all the cities list on all the pages.
Now whenever you click on city page get that city_id and pass it in controllers like
public function city() {
$data['site'] = $this->Site_model->get_site_details();
$data['page_title'] = $data['site']->site_title;
$data['city_id'] = $this->uri->segment(2);
$this->load->view('city_page', $data);
}
Now you can match your city_id in foreach loop data on header page
<ul class="dropdown-menu" role="menu">
<?php foreach ($race_details as $city) {?>
<li>
<a class="dropdown-item <?= ($this->uri->segment(2) == 'id') ? 'active' : ''; ?>" href="<?php echo base_url('city/'. $city->id); ?>" <?= if(isset($city_id)) { if($city->id == $city_id){echo 'selected';}} ?>>
<?= $city->location ?>
</a>
</li>
<?php
}
?>
</ul>
Hope this will helps you.