Wordpress重写规则

Question

UPDATE

I've gone through the codex docs on the rewrite API and now have the following in my functions.php :

function my_rewrite_rules() {
    add_rewrite_rule('(a|b|c|d)/?$', 'index.php?pagename=$matches[1]-overview&myVar=var', 'top');
}
add_action('init', 'my_rewrite_rules');

Yes, I am going to the permalinks page to flush the rules after adjusting. The behavior is the same, the rule above 404s even though the page does exist and I can access it by typing directly into the address bar. However, if I hardcode one of the regex matches like so:

function my_rewrite_rules() {
    add_rewrite_rule('(a|b|c|d)/?$', 'index.php?pagename=a-overview&myVar=var', 'top');
}
add_action('init', 'my_rewrite_rules');

then all works as expected, with query vars set correctly. Ideas?

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ORIGINAL QUESTION

I've been trying to get Wordpress rewrite rules to work for quite some time now and am absolutely stumped as to why the following code (in functions.php) doesn't work:

function my_rewrite_rules($rules) {
    $my_rules = array('(a|b|c|d)/?$' => 'index.php?pagename=$matches[1]-overview&my_var=somevar');

    return array_merge($my_rules, $rules);
}
add_filter('page_rewrite_rules', 'my_rewrite_rules');

I have canonical redirects disabled and the rewrite just 404s. If redirecting is enabled, it does go to the correct page, but my query variable is stripped. If I remove '$matches[1]' and replace it with a, b, c, or d, everything works as expected with canonical redirecting disabled. I realize there are a few workarounds but I just want to understand why the following doesn't work? Thanks!

Answer 1

Apparently having the $matches variable directly after the pagename query variable is treated as a special case in the url_to_post() function of Wordpress. Here is a snippet from that code :

if ( $wp_rewrite->use_verbose_page_rules && preg_match( '/pagename=\$matches\[([0-9]+)\]/', $query, $varmatch ) ) {
    // this is a verbose page match, lets check to be sure about it
    if ( ! get_page_by_path( $matches[ $varmatch[1] ] ) )
        continue;
}

If I read this correctly it seems that Wordpress assumes (incorrectly) that the $matches variable should match the page path. So in your example, if you do not have a page with the name a , b , c or d your rewrite rule will be skipped entirely (continue will be called).

I've deduced this from reading the Wordpress code, but I've not tested my theory (I've actually never worked with Wordpress at all). You could test my theory by making a pages with the names a , b , c , and d and running your code again. If I am correct this should make your rule work. I would suggest not using -overview behind your pagenames, thus solving the problem.