PHP - Smarty Variables unset after header redirect - php

Question

I have a php file (form.php) that uses a template (form.htm) to display a form. The template file's form action is form.php. If the form is incomplete when submitted, I want to redirect back to the form WITHOUT losing information that the user has already input.
I'm setting smarty variables using t->assign('varname', $_POST['var']) and setting the form values to these variables ( value="{$varname}" ), however when redirected using php's header() function, these Smarty variables are lost (which I've confirmed using Smarty {debug}).
Does anyone have any idea of how to make it so that these variables aren't unset when using a header redirect? Thanks!

Answer 1

Smarty is only template engine, so you cannot do here more than in PHP.
But in your case you said you want to make header redirect after sending form (to be honest I have no idea why you want to do it. In normal case you simple set action in form and in controller you simple check data and if they are valid you do what you want - for example send email and if they are not valid you simple show the form again - that's it).
However if you really need to do this that way, what you can do is to use session data and save all data from post to session, make redirection and use that from session to display in Smarty.
So in PHP you can do:
$_SESSION['post_data'] = $_POST;
// now you make redirection
And in file you handle redirection you can simple do:
$smarty->assign('post_data',$SESSION['post_data']);
unset($SESSION['post_data']);
And in template file you can then use:
{$post_data.var}
EDIT
But as I said normally you do it this way in PHP file:
$isValid = false;
if (isset($_POST['submit']) {
$isValid = validateData($_POST);
if ($isValid) {
// do something here - for example send email
}
else {
$smarty->assign('error', 'There were errors in your form. Try again');
}
}
$smarty->assign('is_valid',$isValid);
And in Smarty you do:
{if $isValid}
form was sent
{else}
{if isset($error)}{$error}{/if}
you display form here
{/if}

Answer 2

Don't redirect the user. Just redraw the form. In general, this HTTP workflow should be used when dealing with forms:
GET /form.php - Display the form to the user
POST /form.php - Process the form input
If the form input is invalid, send back form.php
If the form input is valid, save to the database, now redirect the user
So basically you have:
GET
POST (invalid input from the user)
POST (valid input from the user)
REDIRECT