Purge certain pages with post publish or update

I preface this with the note that I haven’t (yet) added in JSON paths to the plugin because I’m waiting for the REST API plugin to hit release candidate. I don’t fancy the idea of adding in things and possibly changing them. I’m picky like that.

There’s a filter at the bottom of the code:

// Filter to add or remove urls to the array of purged urls
        // @param array $purgeUrls the urls (paths) to be purged
        // @param int $postId the id of the new/edited post
        $this->purgeUrls = apply_filters( 'vhp_purge_urls', $this->purgeUrls, $postId );

So you could write your own function to hook into that and pass the JSON urls.

Thank you so much for your reply.
I’m sorry to push this further, but as my coding skills are limited to modifying existing code, how would a function look like for a link like this :
https://www.domain.com/json/get_recent_posts/?count=100 ?
I’m using the standard JSON API plugin for wordpress, not REST. I generally don’t like doing modifications on plugins, but the database just can’t keep up with the high numer of requests without varnish cache.
Thank you.

Okay, so you don’t need to edit the plugin! And in fact, you should never edit existing plugins ?? This plugin has a few filters – https://github.com/Ipstenu/varnish-http-purge/wiki/How-to-Use-Custom-Filters

A custom filter is something you would put in an mu-plugins file: https://codex.www.ads-software.com/Must_Use_Plugins

In this case, I think the best approach would be this:

<?php
function zaone_varnish_urls( $urls, $postid ) {
	$myurl = 'https://www.domain.com/json/get_recent_posts/?count=100';
	array_push( $urls, $myurl ) ;
	return $urls;
}
add_filter( 'vhp_purge_urls', 'zaone_varnish_urls' );

If you have more URLs, it would look like this:

<?php
function zaone_varnish_urls( $urls, $postid ) {
	$myurls = array (
		'https://www.domain.com/json/get_recent_posts/?count=100',
		'https://www.domain.com/json/feedURLthingy',
		'https://www.domain.com/anotherURL',
	);

	if ( !empty($myurls) ) {
		foreach ($myurls as $url) {
			array_push($urls, $url ) ;
		}
	}
	return $urls;
}
add_filter( 'vhp_purge_urls', 'zaone_varnish_urls' );

That’s just a sanity check of course. You COULD just do this:

<?php
function zaone_varnish_urls( $urls, $postid ) {
	array_push($urls, 'https://www.domain.com/json/get_recent_posts/?count=100');
	array_push($urls,'https://www.domain.com/json/feedURLthingy');
	array_push($urls,'https://www.domain.com/anotherURL');
	return $urls;
}
add_filter( 'vhp_purge_urls', 'zaone_varnish_urls' );

The code passes in the Post ID so you can do all sorts of tricks like “If this post has a post type of custom, purge this OTHER URL instead!”