Unset session variable on page reload / setup but exclude AJAX

Question

I'm currently trying to unset a session variable in WordPress if the page get's reloaded. I've tried a lot but it's not working like I want it. This is my function:

/**
 * Unset filter session if page get's reloaded
 */
add_action( 'wp', 'unset_filter_session' );
function unset_filter_session() {
    //Reset sessions on refresh page
    unset( $_SESSION['expenditure_filter'] );
}

It's working but it's working too good. Because when I reload the content-area in WordPress via AJAX, the session get's unset too which should be avoided:

jQuery('#content-area').load(location.href + ' #content-area>*', '');

So how can I do the unset of the session just on page load and exclude AJAX reloads?

Answer 1

Try using wp_doing_ajax() like so:

function unset_filter_session() {
    if ( ! wp_doing_ajax() ) {
        //Reset sessions on refresh page
        unset( $_SESSION['expenditure_filter'] );
    }
}

UPDATE

You can check the answer's revision for this update part..

UPDATE #2

Sorry, I didn't realize that you're loading a page fragment (#content-area) using the jQuery.load() method. Or that you're not using the admin-ajax.php to handle the AJAX request.

So if you're not using the wp_ajax_{action} or wp_ajax_nopriv_{action} action, or with the way you do the AJAX request, you can check whether the X-Requested-With header is set and that its value is XMLHttpRequest, and if so, you can cancel the session unsetting, like so:

function unset_filter_session() {
    if ( empty( $_SERVER['HTTP_X_REQUESTED_WITH'] ) ||
        'XMLHttpRequest' !== $_SERVER['HTTP_X_REQUESTED_WITH'] ) {
        //Reset sessions on refresh page, if not doing AJAX request
        unset( $_SESSION['expenditure_filter'] );
    }
}

That should work because jQuery always sets that header, unless you explicitly remove it — or change its value.

See the headers option on the jQuery.ajax() reference:

The header X-Requested-With: XMLHttpRequest is always added, but its default XMLHttpRequest value can be changed

Note: The header name is X-Requested-With, but in the superglobal $_SERVER, its key is HTTP_X_REQUESTED_WITH. I.e. Don't use $_SERVER['X-Requested-With'].

UPDATE #3

As suggested by Lawrence Johnson, you (ahem, we) should use filter_input():

function unset_filter_session() {
    if ( 'XMLHttpRequest' !== filter_input( INPUT_SERVER, 'HTTP_X_REQUESTED_WITH' ) ) {
        //Reset sessions on refresh page, if not doing AJAX request
        unset( $_SESSION['expenditure_filter'] );
    }
}

(but I kept the previous code for reference)

Answer 2

One thing you could consider doing is adding a header variable to your AJAX requests. Even a GET or POST param would likely to the trick. Perhaps something like this:

/**
 * Unset filter session if page get's reloaded
 */
add_action( 'wp', 'unset_filter_session' );
function unset_filter_session() {
    //Reset sessions on refresh page
    if (!filter_input(INPUT_POST, 'isContentLoader', FILTER_SANITIZE_NUMBER_INT)) {
        unset( $_SESSION['expenditure_filter'] );
    }
}

And then

jQuery('#content-area').load(location.href + ' #content-area>*', { isContentLoader: 1 });