Implement Viewstate in codeigniter - codeigniter

Question

I´ve been working with aspnet for quite a while, and i´d like to implement aspnet viewstate with in php (exactly in codeigniter). Is there a way to implement ASP ViewState with Codeigniter ?

Answer 1

This answer will accomplish some of the goals of Viewstate in that is will preserve control values between form submits. If you navigate away from the page the data will be lost. But it's the same for Viewstate. The example code make heavy use of the CodeIgniter (CI) Framework.
Here is some documentation related to the parts of CI used here.
Form Validation
Form Helper
Session
The CI_Form_validation library suffers from not being able to keep validation results across a redirect. This class extends CI_Form_validation to overcome that limitation.
File: application/libraries/My_Form_validation.php
/**
* Extends CI_Form_validation to facilitate using the Post/Redirect/Get pattern for form handling.
* https://en.wikipedia.org/wiki/Post/Redirect/Get
* http://solidlystated.com/design/best-way-to-process-forms-with-php/
*
* The base class (CI_Form_validation) has the protected property $_field_data
* which holds all the information provided by form_validation->set_rules()
* and all the results gathered by form_validation->run().
* Form Helper and Form_Validation use the $_field_data to re-populate fields and present error messages.
*
* To use this class you must have CodeIgniter Session setup and working.
*
* This class stores $_field_data in session flash data for use in the controller method that is the
* redirect target.
*
* Class is handy for defining custom validation methods which will NOT require the "callback_" prefix.
*
*/
defined('BASEPATH') OR exit('No direct script access allowed');
class MY_Form_validation extends CI_Form_validation
{
public function __construct($rules = array())
{
parent :: __construct($rules);
$this->CI->load->library('session');
}
/**
* Enhanced version of form_validation->run(). Sets a $_SESSION item with the contents of $this->_field_data
*
* #param string $group The name of the validation group to run
* #param bool $persistent If TRUE save the state of $_field_data even if validation passes
* #return boolean TRUE on success and FALSE on failure
*/
public function run($group = '', $persistent = FALSE)
{
if(parent:: run($group))
{
if($persistent)
{
$this->CI->session->set_flashdata('validation_field_data', $this->_field_data);
}
return TRUE;
}
$this->CI->session->set_flashdata('validation_field_data', $this->_field_data);
return FALSE;
}
/**
* This is used in the redirect target defined in the form processing controller/method
*
* #return bool TRUE if $_SESSION['validation_field_data'] is set. It indicates that validation failed.
* Returns FALSE if there is no indication that validation has failed or even been run.
*/
public function is_failed_validation()
{
if(isset($_SESSION['validation_field_data']))
{
// Validation failed or is being persisted.
$this->_field_data = $_SESSION['validation_field_data'];
return TRUE;
}
return FALSE;
}
/**
* A validation function to cleanup strings
*
* #param string $str Value of the field
* #return string|bool The sanitized string or FALSE if filter_var() fails
*/
public function sanitize_str($str)
{
return filter_var($str, FILTER_SANITIZE_STRING);
}
/**
* A do-nothing routine assigned to any field we want included in validation results
* #return boolean
*/
public function alwaysTrue($val)
{
return TRUE;
}
}
Hopefully the comments explain what's going on. One major thing to understand is that form_validation only captures the $_POST data for controls that have validation rules. That's the reason for the "do-nothing" validation routine alwaysTrue(). Use this rule on any control where you want the values to persist.
The following controller shows a usage example.
File: application/controllers/Viewstate.php
class Viewstate extends CI_Controller
{
public function __construct()
{
parent::__construct();
$this->load
->library('form_validation', NULL, 'fv') //renames 'form_validation' to 'fv'
->helper(['form', 'url']);
$this->fv->set_error_delimiters('<span class="error">', '</span>');
}
public function index()
{
$this->fv->is_failed_validation(); //captures validation data if it's there
//Define some data for consumption by CI's Form Helper functions
$data['username_field'] = [
'name' => 'username',
'id' => 'username',
'value' => $this->fv->set_value('username'),
'class' => 'your_css',
];
$data['confirm_username_field'] = [
'name' => 'usernameconf',
'id' => 'usernameconf',
'value' => $this->fv->set_value('usernameconf'),
'class' => 'your_css',
];
$data['comment_field'] = [
'name' => 'comment',
'id' => 'comment',
'value' => $this->fv->set_value('comment'),
'class' => 'comment',
];
$data['project_lead_field'] = [
'name' => 'project_lead',
'value' => 1,
'checked' => $this->fv->set_radio('project_lead', 1, FALSE)
];
$selected_status = ['None' => "None"]; //default dropdown item
$status_items = ["None" => "None", "Good" => "Good", 'Bad' => 'Bad', "Ugly" => "Ugly"];
//recover previously posted select item - if any
if($item = $this->session->validation_field_data['status']['postdata'])
{
$selected_status = [$item => $item];
}
$data['status_field'] = [
'name' => 'status',
'options' => $status_items,
'selected' => $selected_status
];
$this->load->view('testcase_view', $data);
}
/**
* This is the "action" that processes the form's posted data
*/
public function process()
{
//set rules and error messages at same time
$this->fv
->set_rules('username', 'User Name', ['trim', 'required', 'matches[usernameconf]'],
['required' => '<em>{field}</em> required.', 'matches' => "User Names don't match."])
->set_rules('usernameconf', '', ['trim', 'required'], ['required' => 'Retyping the User Name is required.'])
->set_rules('comment', "", ['trim', 'sanitize_str'])
->set_rules('project_lead', "", 'alwaysTrue')
->set_rules('status', "", 'alwaysTrue')
;
//So an uncheck checkbox will be part of the $_POST array
if(!isset($_POST['project_lead']))
{
$_POST['project_lead'] = 0;
}
if(FALSE == $this->fv->run('', TRUE))
{
redirect('viewstate');
}
else
{
//do something with field values e.g.
//$this->model->instert($_POST);
redirect('viewstate'); //to prove the page state is persistent
}
}
}
I included some actual field validation so readers can see how that works and how the validation results persist across a redirect.
Here is the view
File: application/views/textcase_view.php
<!DOCTYPE html>
<html>
<head>
<title>Test Persistent Page</title>
<style type="text/css">
p{
margin: 0;
}
.error {
color: #FF0000;
font-size: small;
}
.fld-label{
color: #555;
font-size: .9em;
}
.comment{
color: Blue;
font-weight: bold;
}
div{
margin-bottom: 1em;
}
div + .fld-label
/*div + .error*/
{
margin-bottom: 0;
}
</style>
</head>
<body>
<?= form_open('viewstate/process'); ?>
<span class="fld-label">User Name</span>
<div><?= form_input($username_field) ?>
<p><?= form_error('username'); ?></p>
</div>
<div class="fld-label">Retype User Name</div>
<div><?= form_input($confirm_username_field) ?>
<p><?= form_error('usernameconf'); ?></p>
</div>
<div class="fld-label">Comment</div>
<div><?= form_input($comment_field); ?></div>
<div class="fld-label">Project Lead?</div>
<div><?= form_checkbox($project_lead_field); ?></div>
<div class="fld-label">Status</div>
<div><?= form_dropdown($status_field); ?></div>
<p><input type="submit" value="Submit"></p>
<?= form_close(); ?>
</body>
</html>
The view makes heavy use of Form Helper functions such as form_open, form_close, form_input, etc.