how do I keep form field populated after using the back button?

I'm building a form in a custom Joomla component. It collects payment details and has a captcha image.
When the form is submitted and the captcha string is incorrect a message is displayed..."incorrect code please try again" and there's a button that takes the user back to re-enter the code.

<form>
 <input type=button value="Go back to payment form" onClick="history.go(-1)">
</form>

when you click this the form appears a gain but all the fields are empty.

How can I make it so that the field retain the information previously entered.

thanks
LVL 2
xoundboyAsked:
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lightitConnect With a Mentor Commented:

Maybe use sessions?

in your page with the al the fields, put this on top
<?php
session_start();
?>

in every value from a field you put this code:
 <?php echo $_SESSION["fieldname"];?>

In the page where you go to after the form is submitted you first do this, you register every session and give it a value

<?php
session_start;
@ session_register("fieldname1"); // The @-sign removes the error if this session is already registered
@ session_register("fieldname2");

$_SESSION("fieldname1") = $_POST["fieldname1"];
$_SESSION("fieldname2") = $_POST["fieldname2"];

// PUT HERE THE REST OF THE CODE
?>

You will see, after you returned to your previous page the fields will be filled with the value,
it is best that you destroy the sessions after the form has a succesfull submit, because otherwhise if the people come back at this page the fields will be still filled in, do that like this
<?php
session_start();
session_destroy();
?>

Sorry for bad english

Greetz
0
 
xoundboyAuthor Commented:
thanks

I tried that but I'm getting this error which I don't understand:

Fatal error: Can't use function return value in write context in /vservers/mydomain/htdocs/test/components/com_payment/form_action.php on line
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xoundboyAuthor Commented:
let me clarify that last comment.

this line:

$_SESSION("students_name") = $_POST["students_name"];

 in the page that the form submits to is generating this error:

Fatal error: Can't use function return value in write context in /vservers/mydomain/htdocs/test/components/com_payment/form_action.php on line 19

 what is wrong with setting a session variable like this?
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lightitConnect With a Mentor Commented:
Sorry my bad!

$_SESSION["students_name"] = $_POST["students_name"];

That is the right way! It was already very late yesterday
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xoundboyAuthor Commented:

I followed your instructions very carefully. It still doesn't work though. It could be something to do with the fact that the form is being included into a joomla index.php page, its URL being:

www.mydomain.com/index.php?option=com_payment

I tried dumping the conents of the session variable just before the form and it appears to be empty - hence the fields not being repopulated. The strange thing is though that if I run the same session dump script afterwards from a non index.php  location then the session is still alive and the values are still held there. This would imply that joomla's index controller is hiding the session variables from the form but without actually destroying them. It's very frustrating.

Anyone have any ideas? Anyone know the Joomla framework? This is the 1st time I'm developing a component for Joomla so it's all a bit strange.

HELP!
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xoundboyAuthor Commented:
I've had another go at it and realised that I forgot to add one field to the list of session_register('fieldname"); 's. Now it works :)

0
 
xoundboyAuthor Commented:
thanks very much - great answer
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