I am trying to solve a rewrite problem but don’t fully understand how to read the below code.
I believe the event/industry/(.+)/?$' is stating the format I want in my new url after rewritten, which should be example.com/event/industry/someterm/
And this part appears to be the parameter. => 'index.php?post_type=eg_event&industry=' . $wp_rewrite->preg_index(1)
Is this a correct understanding?
What is telling this code what value to place in my new url where this is: (.+)/?$' Is it the $wp_rewrite->preg_index(1) and what exactly does the preg_index(1) mean?
$new_rules = array(
'event/industry/(.+)/?$' => 'index.php?post_type=eg_event&industry=' . $wp_rewrite->preg_index(1)
);
$wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
}
Any assistance you can provide with helping me understand the logic above it much appreciated.
'event/industry/(.+)/?$'
The above is the URL that will be rewritten behind the scenes. The brackets create what is known as a “backreference”.
'index.php?post_type=eg_event&industry=' . $wp_rewrite->preg_index(1)
The above is the actual URL that will be served to the browser.
So, http://yourdomain.com/event/industry/abc/ matches the rule “event/industry/(.+)/?$”. The term ‘abc’ becomes a backreference with index 1, because it matches the term enclosed in brackets.
When someone browses to that URL, the server will then silently rewrite that URL to “index.php?post_type=eg_event&industry=abc”, and serve that page instead. This “rewrite” is not visible to the browser/end-user.
$wp_rewrite->preg_index(1) simply refers to backreference with index 1.
You can have multiple backreferences. For instance:
event/(.+)/(.+)/?$
Now this rule will match http://yourdomain.com/event/magic/def/.
This time, “magic” becomes backreference with index 1, while “def” becomes backreference with index 2.
So you could rewrite the rule to:
index.php?post_type=eg_event&' . $wp_rewrite->preg_index(1) . '=' . $wp_rewrite->preg_index(2)
i.e. index.php?post_type=eg_event&magic=def
