Controllers placed in Sub-Folders have no content - php

Question

I am using a PHP Framework for the first time to get away from writing spaghetti code and so far it is wonderful. I am using Code Igniter and have a base Controller named "Dashboard.php" that loads fine and looks perfect.
When attempting to create some organization, I placed my "Devices.php" into a "Controllers/Devices" sub-folder, then accessed it at "http://domain.com/devices/devices" which loads the text, but the images/css/etc. are missing.
The content of the "Devices" controller is exactly the same as my "Dashboard" so I am not understanding why only the text loads. If I move the "devices.php" file into the root Controllers directory, there are no problems.
class Devices extends CI_Controller
{
public function index()
{
$data['page_title'] = 'Device Portal';
$this->load->view('meta');
$this->load->view('sidebar');
$this->load->view('userbar');
$this->load->view('header');
$this->load->view('devices/content');
$this->load->view('footer');
}
}
Here is the "Sidebar.php" View...
<!-- Left side content -->
<div id="leftSide">
<div class="logo"><img src="assets/images/logo.png" alt="" /></div>
<div class="sidebarSep mt0"></div>
<!-- Search widget -->
<form action="" class="sidebarSearch">
<input type="text" name="search" placeholder="search..." id="ac" />
<input type="submit" value="" />
</form>
<div class="sidebarSep"></div>
<!-- General balance widget -->
<div class="genBalance">
<a href="#" title="" class="amount">
<span>General balance:</span>
<span class="balanceAmount">$10,900.36</span>
</a>
<a href="#" title="" class="amChanges">
<strong class="sPositive">+0.6%</strong>
</a>
</div>

Answer 1

You need to avoid using relative paths when linking to images/css/etc in your views.
As an example, when you use assets/images/logo.png (relative path) from the page http://domain.com/devices/devices, the browser looks for http://domain.com/devices/assets/images/logo.png
Using the same image path with the page http://domain.com/devices the browser will look for http://domain.com/assets/images/logo.png instead.
When specifying urls to pages, images, etc within your domain, use the URL helper functions to automatically format your urls.
You want to avoid writing urls like this:
<script type="text/javascript" src="./assets/js/jquery.js"></script>
<img src="assets/images/logo.png" alt="" />
And instead generate your urls like this:
<script type="text/javascript" src="<?php echo base_url('assets/jquery.js'); ?>"></script>
<img src="<?php echo base_url('assets/images/logo.png'); ?>" alt="" />
Which will output:
<script type="text/javascript" src="http://domain.com/assets/js/jquery.js"></script>
<img src="http://domain.com/assets/images/logo.png" alt="" />

Answer 2

In Codeigniter use base_url() function to print assets.
<img src="<?php echo base_url('assets/images/logo.png');?>" alt="" />
This function automatically generate domain before the url.