Wordpress script to create custom pretty urls, and set query variables for filtering

custom-pretty-url-rewrite.php

<?php

function customQueryVar($vars) {
    $vars[] = "year_filter";
    return $vars;

}
// hook add_query_vars function into query_vars
add_filter('query_vars', 'customQueryVar');

function custom_rewrite_rule() {

    add_rewrite_rule('^year-posted/([^/]*)?','index.php?post_type=posts&year_filter=$matches[1]','top');

}

add_action('init', 'custom_rewrite_rule', 10, 0);

function alterQuery($query) {
    
    if ( ! is_admin() and $query->is_main_query() && is_post_type_archive('post') ) {
        
        $year = date('Y', current_time( 'timestamp' ) );
        
        if( isset( $wp_query->query_vars['year_filter'] ) ) {

            $yearSet = $wp_query->query_vars['year_filter'];

        }
        
         if( isset( $yrNominated ) and ! empty( $yrNominated ) ) {

            $yearSet = (int) $yearSet;

            // Ensure the year requested is real
            if( $yearSet > 1000 and $yearSet < 2100 ) {
                $year = $yearSet;
            }

        }

        $query->set( 'meta_query', array(

            array(

                'key'       =>  'year',
                'value'     =>  $year,
                'compare'   =>  '='

            )

        ) );
        
    }
    
}

add_action('pre_get_posts','alterQuery');

template-file.php

<?php


$yearRequested = get_query_var( 'year_filter', false );