Question

I have a PHP site (with CodeIgniter) that includes a registration form. I have a page with some details, which links to the form on a separate page. The form posts to a third URL which does the processing and redirects back to the first page if it’s successful (or the form page if not).

Currently I am adding a parameter for success: example.com/page?success=1 which shows a success message. The problem is that some people have been sharing this URL (and clicking the Facebook Like button) so when another user opens that URL they see a message “thanks for registering!” which they obviously haven’t done yet.

I thought this was the standard way of doing forms (submitting to one URL and redirecting to another) but is there a better way? I don’t want to post back to the same page because then you get the POSTDATA warning when trying to reload the page.

Answer 1

Typically you would set your flag for success in the session to display this message when the next page loads. This is commonly referred to as a Flash Message. You would then check the value/existence of this session flag and show your message or not accordingly. In most frameworks there is built in functionality for this which includes the clean up of the flag on the next request so that the message is only displayed directly after the action generating it is taken.

From the CI Sessions Documentation:

CodeIgniter supports “flashdata”, or session data that will only be
available for the next server request, and are then automatically
cleared. These can be very useful, and are typically used for
informational or status messages (for example: “record 2 deleted”).

Note: Flash variables are prefaced with “flash_” so avoid this prefix
in your own session names.

To add flashdata:

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

You can also pass an array to set_flashdata(), in the same manner as
set_userdata().

To read a flashdata variable:

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

If you find that you need to preserve a flashdata variable through an
additional request, you can do so using the keep_flashdata() function.

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