Title: [PATH] Clear cache button
Last modified: August 21, 2016
---
# [PATH] Clear cache button
* [flynsarmy](https://wordpress.org/support/users/flynsarmy/)
* (@flynsarmy)
* [13 years ago](https://wordpress.org/support/topic/path-clear-cache-button/)
* I noticed there’s no clear cache button. This can be an issue for example when
you change the date or add new posts that should relate to a previous one.
* As an example if you have Post X that has a Post Y in its related post list then
change the date on Post Y, the URL on the cached post list on the Post X page
won’t update accordingly and it’ll lead to a 404.
Another example is if you
create Post X and it has no related posts. If you then create Post Y and want
it to relate to X, you probably want Y to appear in X’s related post list. A
clear cache button is required to do this so next page load a new related post
list is generated.
* I added a simple ‘Clear Cache’ button to the admin like so. In _admin.inc.php_
below
* ```
```
* add
* ```
```
* and above
* ```
function checkForm() {
```
* in the JS at the bottom of the file add
* ```
function clearCache() {
// since 2.8 ajaxurl is always defined in the admin header and points to admin-ajax.php
jQuery.post(ajaxurl, {action: 'crp_clear_cache'}, function(response, textStatus, jqXHR) {
alert( response.message );
}, 'json');
}
```
*
That’s the HTML taken care of, now for the actual logic to delete the cache.
In _contextual-related-posts.php_ at the bottom above
* ```
// End admin.inc
```
* add
* ```
add_action('wp_ajax_crp_clear_cache', 'crp_ajax_clearcache');
function crp_ajax_clearcache() {
global $wpdb; // this is how you get access to the database
$rows = $wpdb->query("
DELETE FROM " . $wpdb->postmeta . "
WHERE meta_key='crp_related_posts'
");
// Did an error occur?
if ( $rows === false )
exit(json_encode(array(
'success' => 0,
'message' => "An error occurred clearing the cache. Please contact your site administrator.\n\nError message:\n" . $wpdb->print_error(),
)));
// No error, return the number of
else
exit(json_encode(array(
'success' => 1,
'message' => $rows . " cached row(s) cleared.",
)));
}
```
*
While I was in there I also fixed an error you get when updating settings with
WP_DEBUG turned on:
* > Notice: Undefined index: post_types in _/path/to/wp-content/plugins/contextual-
> related-posts/admin.inc.php_ on line 84
* by changing
* ```
$post_types_arr = (is_array($_POST['post_types'])) ? $_POST['post_types'] : array('post' => 'post');
```
* to
* ```
$post_types_arr = (isset($_POST['post_types']) && is_array($_POST['post_types'])) ? $_POST['post_types'] : array('post' => 'post');
```
* [http://wordpress.org/extend/plugins/contextual-related-posts/](http://wordpress.org/extend/plugins/contextual-related-posts/)
Viewing 4 replies - 1 through 4 (of 4 total)
* Plugin Author [Ajay](https://wordpress.org/support/users/ajay/)
* (@ajay)
* [13 years ago](https://wordpress.org/support/topic/path-clear-cache-button/#post-3797596)
* Thank you. Two quick questions.
* 1. Do we need to use nonces to secure the response?
* 2. You have `{action: 'crp_clear_cache'}` and `function crp_ajax_clearcache(){`
Do these have to be same?
* Thread Starter [flynsarmy](https://wordpress.org/support/users/flynsarmy/)
* (@flynsarmy)
* [13 years ago](https://wordpress.org/support/topic/path-clear-cache-button/#post-3797597)
* No nonce required. The response comes from WP AJAX url which is secure and we
don’t do anything with it other than alert anyway.
* The action ‘wp_ajax_crp_clear_cache’ triggers the wordpress event wp_ajax_crp_clear_cache
which I’ve attached to the callback function crp_ajax_clearcache. You can rename
the callback function to anything you like, that’s just what I named mine.
* If you want to change the action name, you’ll need to change teh WP event name
to match.
* ```
{action: 'foo'}
add_action('wp_ajax_foo', ...
```
* See [AJAX in Plugins](http://codex.wordpress.org/AJAX_in_Plugins) for more information.
* Plugin Author [Ajay](https://wordpress.org/support/users/ajay/)
* (@ajay)
* [13 years ago](https://wordpress.org/support/topic/path-clear-cache-button/#post-3797600)
* Thank you. That clears. I’m giving the code a test drive on my install
* Plugin Author [Ajay](https://wordpress.org/support/users/ajay/)
* (@ajay)
* [12 years, 12 months ago](https://wordpress.org/support/topic/path-clear-cache-button/#post-3797751)
* This has been implemented in v1.8.8 that I released today
Viewing 4 replies - 1 through 4 (of 4 total)
The topic ‘[PATH] Clear cache button’ is closed to new replies.
* 
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* 4 replies
* 2 participants
* Last reply from: [Ajay](https://wordpress.org/support/users/ajay/)
* Last activity: [12 years, 12 months ago](https://wordpress.org/support/topic/path-clear-cache-button/#post-3797751)
* Status: not a support question