CodeIgniter: setting flash data not working

Question

I'm using the following code to manage pagination in search results:

if ($this->input->post('search-notes') && (is_string($this->input->post('search-notes')) || is_string($this->input->post('search-notes')))):
    $this->session->set_flashdata('search-notes', $_POST['search-notes']);
    $post['search-notes'] = $this->input->post('search-notes');
elseif ($this->session->flashdata('search-notes')):
    $this->session->set_flashdata('search-notes', $this->session->flashdata('search-notes'));
    $post['search-notes'] = $this->session->flashdata('search-notes');
endif;
if (isset($post['search-notes']) && is_string($post['search-notes']) && !empty($post['search-notes'])):
...

All of which works fine on my development computer, but chokes on the live website; the final if() statement does not evaluate to true.

However, if I echo out the $post['search-notes'] variable either before or within the final if() statement, it works!

It's utterly bizarre, and I've never encountered anything like it before.

I'm using CodeIgniter 2.0

On a side note, the original title had much more specificity: "Problem with set_flashdata() function in CodeIgniter". But due to some excitable and excessive moderation rules, I've had to water it down to something less meaningful.

Answer 1

The first thing you should attend is once you call $this->session->flashdata('search-notes') method, it unsets the 'search-notes' item from session.

So, when you check the $this->session->flashdata('search-notes') at the second time, 'search-notes' will no longer exists.

If you want to keep the item in session, use set_userdata() and userdata() instead.

Also, you can use keep_flashdata('search-notes') after set_flashdata() or before the first call of flashdata() to preserve the flashdata variable through an additional request.

As a side point:
There's no need to check isset() and !empty() together. empty() does NOT generate a warning if the variable does not exist, and returns FALSE.

CI reference

There is also a nice tutorial on nettuts+ could be useful.

---

Jus as a Demo:
do NOT copy, check the logic.

if ($_POST['search-notes'] AND is_string($_POST['search-notes']))
{
    $post['search-notes'] = $this->input->post('search-notes'/*, TRUE*/ /* Enable XSS filtering */);
    $this->session->set_flashdata('search-notes', $post['search-notes']);
}
elseif ($searchNotes = $this->session->flashdata('search-notes'))
{
    $post['search-notes'] = $searchNotes;
}

if (! empty($post['search-notes']) AND is_string($post['search-notes'])):
// ...

If you need to keep the search-notes item in session, use the following at the first if statement:

if ($_POST['search-notes'] AND is_string($_POST['search-notes']))
{
    $post['search-notes'] = $this->input->post('search-notes'/*, TRUE*/ /* Enable XSS filtering */);
    $this->session->set_flashdata('search-notes', $post['search-notes']);
    // Keep the flashdata through an additional request
    $this->session->keep_flashdata('search-notes');

} // ...