Question

I am using this function to redirect to a random post. I am trying to find a mechanism to prevent the same random post to appear twice in a row. Can anyone give a hint?

function sofa_view_random_post() {

    // make array of all posts IDs
    $q = get_posts('numberposts=-1');
    $array = array();
    foreach($q as $p) {
        $array[] = $p->ID;
    }

    // randomize array to get random post
    $k = array_rand($array);
    $v = $array[$k];
    wp_redirect( get_permalink( $v ) ); exit;

}

I get all posts IDs first and put them to array. I randomize the array to get a value. But not sure how to prevent same value from being triggered.

Answer 1

Store the previous result in the session, and make sure you don’t pick that one again:

if( !isset( $_SESSION['last_random_post'])) {
    $_SESSION['last_random_post'] = -1;
}

do {
    $k = array_rand( $array);
} while( $k == $_SESSION['last_random_post']);

$_SESSION['last_random_post'] = $k;

I’m not sure how this applies to wordpress specifically, but it should be easily adaptable:

For completeness, here is the function incorporating the above code:

function sofa_view_random_post() {

    if( !isset( $_SESSION['last_random_post'])) {
        $_SESSION['last_random_post'] = -1; // Or null, as long as its an invalid ID
    }

    // make array of all posts IDs
    $q = get_posts('numberposts=-1');
    $array = array();
    foreach($q as $p) {
        $array[] = $p->ID;
    }

    // randomize array to get random post
    do {
        $k = array_rand( $array);
    } while( $k == $_SESSION['last_random_post']);

    $_SESSION['last_random_post'] = $k;

    $v = $array[$k];
    wp_redirect( get_permalink( $v ) ); exit;
}