Code to change the WordPress re-write slugs based on the Author and Faculty parameters

author_and_faculty_rewrite_slugs.php

<?php

// Add the following re-write rule to the CPT, out of context here so commented out
//'rewrite' => array( 'slug' => __( '%faculty%/%author%/journal', 'aspire' ) ),

function aspire_register_rewrite_tags() {
	// add our rewrite tags
	// query at the end allows a custom param, however having it at the start of our URL with no prefix does cause issues
	add_rewrite_tag( '%faculty%', '([^&]+)' /*, 'author='*/ );
}
add_action( 'init', 'aspire_register_rewrite_tags');

// This does the URL rewrite based on the rewrite tags
function aspire_post_type_link( $post_link, $post, $leavename, $sample ) {

	// Check that we are on a Journal page (however we probably want to check a few of these)
	if ( 'journal' != get_post_type( $post ) )
        	return $post_link;

	$authordata = get_userdata( $post->post_author );
	$author     = $authordata->user_nicename;

	// Replace the Author
	$post_link = str_replace( '%author%', $author, $post_link );

	// Replace the faculty (we can use custom meta, but this is good for a test)
	$post_link = str_replace( '%faculty%', 'my-test-faculty', $post_link );

   	return $post_link;
}
add_filter( 'post_type_link', 'aspire_post_type_link', 10, 4 );