How to avoid browser cache using Codeigniter

问题:

Facing issue related to browser chache.

function doUpload(){

  $data['includeView'] = "profileconfirm";

 $config['upload_path'] = './img/images/uploaded/';
 $config['allowed_types'] = 'gif|jpg|png|jpeg';
 $config['max_size'] = '5000';
 $config['max_width']  = '1024';
 $config['max_height']  = '768';
 $config['file_ext'] =".jpeg";
 $config['file_name'] = $profileId.$config['file_ext'];
 $config['overwrite'] = TRUE;
 $this->load->library('upload', $config);

 $query = null ; 

 if ( ! $this->upload->do_upload()){
  // Error here
 }else{
 // Image uploaded sucess fully
 // $profile - business logic to populate $profile

  $data['PROFILE_DETAILS'] = $profile;

 $this->load->view('index', $data);
}

this method is used for image upload. After successful image upload, it loads index view page, which internally includes profileconfirm view page.

But on profileconfirm page new uploaded image is not going to reflect. Some times it works fine, but some times not, this is happen most of the times.

Please help

回答1:

You can send proper headers to the client to disable the cache:

....
$this->output->set_header("HTTP/1.0 200 OK");
$this->output->set_header("HTTP/1.1 200 OK");
$this->output->set_header('Last-Modified: '.gmdate('D, d M Y H:i:s', $last_update).' GMT');
$this->output->set_header("Cache-Control: no-store, no-cache, must-revalidate");
$this->output->set_header("Cache-Control: post-check=0, pre-check=0");
$this->output->set_header("Pragma: no-cache");
$this->load->view('index', $data);

Note: Output class is initialized automatically

回答2:

Just add a timestamp to the src attribute of the image being displayed.

<img src="filename.jpg?<?php echo time(); ?>">

To disable the cache completely with one line of code (after extending the Output library) review http://www.robertmullaney.com/2011/08/13/disable-browser-cache-easily-with-codeigniter/
Disclaimer, my blog

_{Edit 1: The accepted solution is overkill in my opinion when all you want to do force-reload the image in the browser ;)
Edit 2: Simplified the suggested solution.}

回答3:

Try the following:

if (!$this->upload->do_upload())
{
    $error = array('errors' => $this->upload->display_errors("<li>","</li>"));
    $this->load->view('index', $error);
}else{
    $data['PROFILE_DETAILS'] = $profile;
    $this->load->view('index', $data);
}

and then display the errors in your view like so:

<?php if($errors): ?>
   <ul><?php print $errors ?></ul>
<?php endif; ?>

and see what errors your getting.