CodeIgniter - Flashdata

Flashdata

While  building  web  application,  we  need  to  store  some  data  for  only  one  time  and  after that  we  want  to  remove  that  data.  For  example,  to  display  some  error  message  or information  message.  In  PHP,  we  have  to  do  it  manually  but  CodeIgniter  has  made  this job  simple  for  us.  In  CodeIgniter,  flashdata  will  only  be  available  until  the  next  request, and it will get deleted automatically.
Add Flashdata

We can simply store flashdata as shown below.
$this->session->mark_as_flash('item');

· mark_as_flash()   function   is   used   for   this   purpose,   which   takes   only   one argument  of  the  value  to  be  stored.  We  can  also  pass  an  array  to  store  multiple values.


· set_flashdata()  function  can  also  be  used,  which  takes  two  arguments,  name and value, as shown below. We can also pass an array.

$this->session->set_flashdata('item','value');

Retrieve Flashdata

Flashdata  can  be  retrieved  using  the  flashdata()  function  which  takes  one  argument  of the  item  to  be  fetched  as  shown  below.  flashdata()  function  makes  sure  that  you  are getting only flash data and not any other data.

$this->session->flashdata('item');

If you do not pass any argument, then you can get an array with the same function.

Example
Create  a  class  called  FlashData_Controller.php and save it at application/controller/FlashData_Controller.php.

<?php
class  FlashData_Controller  extends  CI_Controller  {
public  function  index()
{
//Load  session  library

$this->load->library('session');
//redirect  to  home  page
$this->load->view('flashdata_home');
}
public  function  add(){
//Load  session  library
$this->load->library('session');
$this->load->helper('url');
//add  flash  data
$this->session->set_flashdata('item','item-value');
//redirect  to  home  page redirect('flashdata');
}
}

?>

Create   a   view   file   called   flashdata_home.php   and   save   it   in   application/views/ flashdata_home.php

<!DOCTYPE  html>
<html  lang="en">
<head>
<meta  charset="utf-8">
<title>CodeIgniter  Flashdata  Example</title>
</head>
<body>
Flash  Data  Example
<h2><?php  echo  $this->session->flashdata('item');  ?></h2>
<a  href='flashdata/add'>Click  Here</a>  to  add  flash  data.
</body>
</html>

Make  the  changes  in  the  routes.php  file  in  application/config/routes.php  and  add the following line at the end of the file.

$route['flashdata']  =  'FlashData_Controller';

$route['flashdata/add']  =  'FlashData_Controller/add';

Execute  the  above  example  by  visiting  the  following  link.  Replace  the  yoursite.com  with the URL of your site.
http://yoursite.com/index.php/flashdata

After visiting the above URL, you will see a screen as shown below. 
Figure: Flashdata Example

Click  on  “Click  Here”  link  and  you  will  see  a  screen  as  shown  below.  Here,  in  this screen  you  will  see  a  value  of  flash  data  variable.  Refresh  the  page  again  and  you  will see a screen like above and flash data variable will be removed automatically.



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