WordPress has great filter support for getting at all sorts of specific bits of content and modifying it before output. Like the_content filter, which lets you access the markup for a post before it's output to the screen.
I'm trying to find a catch-all filter that gives me one last crack at modifying the final markup in its entirety before output.
I've browsed the list of filters a number of times, but nothing jumps out at me:
https://codex.wordpress.org/Plugin_API/Filter_Reference
Anyone know of one?
WordPress doesn't have a "final output" filter, but you can hack together one. The below example resides within a "Must Use" plugin I've created for a project.
Note: I haven't tested with any plugins that might make use of the "shutdown" action.
The plugin works by iterating through all the open buffer levels, closing them and capturing their output. It then fires off the "final_output" filter, echoing the filtered content.
Sadly, WordPress performs almost the exact same process (closing the open buffers), but doesn't actually capture the buffer for filtering (just flushes it), so additional "shutdown" actions won't have access to it. Because of this, the below action is prioritized above WordPress's.
wp-content/mu-plugins/buffer.php
<?php
/**
* Output Buffering
*
* Buffers the entire WP process, capturing the final output for manipulation.
*/
ob_start();
add_action('shutdown', function() {
$final = '';
// We'll need to get the number of ob levels we're in, so that we can iterate over each, collecting
// that buffer's output into the final output.
$levels = ob_get_level();
for ($i = 0; $i < $levels; $i++) {
$final .= ob_get_clean();
}
// Apply any filters to the final output
echo apply_filters('final_output', $final);
}, 0);
An example of hooking into the final_output filter:
<?php
add_filter('final_output', function($output) {
return str_replace('foo', 'bar', $output);
});
Edit:
This code uses anonymous functions, which are only supported in PHP 5.3 or newer. If you're running a website using PHP 5.2 or older, you're doing yourself a disservice. PHP 5.2 was released in 2006, and even though Wordpress (edit: in WP version < 5.2) STILL supports it, you should not use it.
The question is may be old, but I have found a better way to do it:
function callback($buffer) {
// modify buffer here, and then return the updated code
return $buffer;
}
function buffer_start() { ob_start("callback"); }
function buffer_end() { ob_end_flush(); }
add_action('wp_head', 'buffer_start');
add_action('wp_footer', 'buffer_end');
Explanation
This plugin code registers two actions – buffer_start and buffer_end.
buffer_start is executed at the end of the header section of the html. The parameter, the callback function, is called at the end of the output buffering. This occurs at the footer of the page, when the second registered action, buffer_end, executes.
The callback function is where you add your code to change the value of the output (the $buffer variable). Then you simply return the modified code and the page will be displayed.
Notes
Be sure to use unique function names for buffer_start, buffer_end, and callback, so they do not conflict with other functions you may have in plugins.
AFAIK, there is no hook for this, since the themes uses HTML which won't be processed by WordPress.
You could, however, use output buffering to catch the final HTML:
<?php
// example from php.net
function callback($buffer) {
// replace all the apples with oranges
return (str_replace("apples", "oranges", $buffer));
}
ob_start("callback");
?>
<html><body>
<p>It's like comparing apples to oranges.</p>
</body></html>
<?php ob_end_flush(); ?>
/* output:
<html><body>
<p>It's like comparing oranges to oranges.</p>
</body></html>
*/
#jacer, if you use the following hooks, the header.php also gets included.
function callback($buffer) {
$buffer = str_replace('replacing','width',$buffer);
return $buffer;
}
function buffer_start() { ob_start("callback"); }
function buffer_end() { ob_end_flush(); }
add_action('after_setup_theme', 'buffer_start');
add_action('shutdown', 'buffer_end');
I was using the top solution of this post (by kfriend) for a while. It uses an mu-plugin to buffer the whole output.
But this solution breaks the caching of wp-super-cache and no supercache-files are generated when i upload the mu-plugin.
So: If you are using wp-super-cache, you can use the filter of this plugin like this:
add_filter('wp_cache_ob_callback_filter', function($buffer) {
$buffer = str_replace('foo', 'bar', $buffer);
return $buffer;
});
Modified https://stackoverflow.com/users/419673/kfriend answer.
All code will be on functions.php. You can do whatever you want with the html on the "final_output" filter.
On your theme's 'functions.php'
//we use 'init' action to use ob_start()
add_action( 'init', 'process_post' );
function process_post() {
ob_start();
}
add_action('shutdown', function() {
$final = '';
// We'll need to get the number of ob levels we're in, so that we can iterate over each, collecting
// that buffer's output into the final output.
$levels = ob_get_level();
for ($i = 0; $i < $levels; $i++) {
$final .= ob_get_clean();
}
// Apply any filters to the final output
echo apply_filters('final_output', $final);
}, 0);
add_filter('final_output', function($output) {
//this is where changes should be made
return str_replace('foo', 'bar', $output);
});
You might try looking in the wp-includes/formatting.php file. For example, the wpautop function.
If you are looking for doing something with the entire page, look at the Super Cache plugin. That writes the final web page to a file for caching. Seeing how that plug-in works may give you some ideas.
Indeed there was a discusussion recently on the WP-Hackers mailing list about the topic of full page modification and it seems the consensus was that output buffering with ob_start() etc was the only real solution. There was also some discussion about the upsides and downsides of it: http://groups.google.com/group/wp-hackers/browse_thread/thread/e1a6f4b29169209a#
To summarize: It works and is the best solution when necessary (like in the WP-Supercache plugin) but slows down overall speeds because your content isn't allowed to be sent to the browser as its ready, but instead has to wait for the full document to be rendered (for ob_end() ) before it can be processed by you and sent to the browser.
To simplify previous answers, just use this in functions.php:
ob_start();
add_action('shutdown', function () {
$html = ob_get_clean();
// ... modify $html here
echo $html;
}, 0);
I've been testing the answers here now for a while, and since the cache breaking thing is still an issue, I came up with a slightly different solution. In my tests no page cache broke. This solution has been implemented into my WordPress plugin OMGF (which has 50k+ users right now) and no issues with page cache breaking has been reported.
First, we start an output buffer on template redirect:
add_action('template_redirect', 'maybe_buffer_output', 3);
function maybe_buffer_output()
{
/**
* You can run all sorts of checks here, (e.g. if (is_admin()) if you don't want the buffer to start in certain situations.
*/
ob_start('return_buffer');
}
Then, we apply our own filter to the HTML.
function return_buffer($html)
{
if (!$html) {
return $html;
}
return apply_filters('buffer_output', $html);
}
And then we can hook into the output by adding a filter:
add_filter('buffer_output', 'parse_output');
function parse_output($html)
{
// Do what you want. Just don't forget to return the $html.
return $html;
}
Hope it helps anyone.
I have run into problems with this code, as I end up with what seems to be the original source for the page so that some plugins has no effect on the page. I am trying to solve this now - I haven't found much info regarding best practises for collecting the output from WordPress.
Update and solution:
The code from KFRIEND didnt work for me as this captures unprocessed source from WordPress, not the same output that ends up in the browser in fact. My solution is probably not elegant using a globals variable to buffer up the contents - but at least I know get the same collected HTML as is delivered to the browser. Could be that different setups of plugins creates problems but thanks to code example by Jacer Omri above I ended up with this.
This code is in my case located typically in functions.php in theme folder.
$GLOBALS['oldschool_buffer_variable'] = '';
function sc_callback($data){
$GLOBALS['final_html'] .= $data;
return $data;
}
function sc_buffer_start(){
ob_start('sc_callback');
}
function sc_buffer_end(){
// Nothing makes a difference in my setup here, ob_get_flush() ob_end_clean() or whatever
// function I try - nothing happens they all result in empty string. Strange since the
// different functions supposedly have very different behaviours. Im guessing there are
// buffering all over the place from different plugins and such - which makes it so
// unpredictable. But that's why we can do it old school :D
ob_end_flush();
// Your final HTML is here, Yeeha!
$output = $GLOBALS['oldschool_buffer_variable'];
}
add_action('wp_loaded', 'sc_buffer_start');
add_action('shutdown', 'sc_buffer_end');
If you want to modify the output, you can use template_include:
add_filter( 'template_include', static function ( $template ) {
if ( basename( $template ) === 'foo-template.php' ) {
echo str_replace( 'foo', 'bar', file_get_contents( $template ) );
}
return null;
} );
If instead you want to override the output completely, you can use the action template_redirect.
add_action( 'template_redirect', static function () {
wp_head();
echo 'My output.';
wp_footer();
exit;
} );
I have a WP shortcode that is giving me problems.
Basically, the shortcode just pulls content from another post using a couple of parameters. It then loads up a partial template.
The problem occurs in WP Admin when saving the page that contains the shortcode. When saving the page updates do in fact save correctly but the resulting page is a page that outputs the contents of the shortcode.
I'm using output buffering around get_template_part() for two reasons: 1. So I only have one instance of the template in my code - and - 2. Because the template is actually pretty substantial and appending all of it to an output variable would be a daunting task.
The shortcode works fine in every way except when saving the page.
Here is a video demonstrating the issue:
https://www.awesomescreenshot.com/video/1146323?key=103ae00d841b47cee8a902eb18c8988a
Here is my code:
function get_main_page_content( $atts ) {
$main_page_id = $atts['main_page_id'];
$section = $atts['section'];
$people_display_option = $atts['people_display_option'];
$GLOBALS['sc_display_option'] = $people_display_option;
ob_start();
if(have_rows('flexible_content', $main_page_id)):
while(have_rows('flexible_content', $main_page_id)): the_row();
if ( $section == 'agenda' ) {
get_template_part('partials/agenda');
}
if ( $section == 'people_cards' ) {
get_template_part('partials/people-cards');
}
endwhile;
endif;
ob_end_flush();
$output = ob_get_contents();
ob_end_clean();
return $output;
}
add_shortcode('get_main_page_content', 'get_main_page_content');
It looks to me like ob_end_flush() is not needed and is redundant. That might be causing the OB to send twice, resulting in that code on your screen.
I'd be curious if your problem persists if you drop that line. Also, for a very simplified version of your exact usecase, check this blog post:
https://konstantin.blog/2013/get_template_part-within-shortcodes
I am having a bit of trouble here understanding how to do the following. I have searched for weeks now but cannot seem to find what I am looking for.
I have a custom post type 'product' and want to change which template gets loaded for the single product page as well as the archive for the products. I am using the following code to load include and load templates.
add_filter('template_include', function() {
if (is_post_type_archive('product')) {
$templatefilename = 'archive-product.php';
$template = WPVS_PATH . 'templates/' . $templatefilename;
return $template;
}
if ('product' == get_post_type() ){
$templatefilename = 'single-product.php';
$template = WPVS_PATH . 'templates/' . $templatefilename;
return $template;
}
});
The problem I am having is that it replaces the current theme's template instead of just the inner part of the content and archive areas.
Here is what I want to achieve:
Create a custom post type 'product' in a plugin - DONE (Was kinda easy!)
When opening a single product only change the content part. - I can do this with the_content filter hook. Simple enough. Any other suggestions is welcome.
When I go to the archive view for the 'product' custom post type I don't want to have it load the theme's default archive (list) view but instead a grid view from my plugin which I cannot seem to get right. I only want to change the inner part of the template, not the whole page.
I have created this plugin a few weeks ago using only shortcodes which works good but want to see if I can do it without the use of shortcodes by means of creating the custom post type and changing the inner template parts of the current active theme.
Can anybody steer me into the right direction here?
If I create a theme I can do what I am looking for but I want to create this into a plugin instead without adding or making changes to the active theme. The plugin should handle what is needed.
The same issue is discussed here but what I want is to develop something that is theme independent. No changes should be made in theme files and no theme files should be copied to the plugin.
WP - Use file in plugin directory as custom Page Template?
Recently I also had the same problem. Here's how I worked it out.
template_include filter accepts a parameter which is the selected template that you want to override (this what you are missing in your code).
I don't know but sometimes the filter hook need higher priority to work like 9999. But first check if it work with default priority, if don't change it.
I assume your both archive and single product template both have include get_header() and get_footer() which can be used for default selected theme (Or if the theme has different setup, setup accordingly).
This is simplified code:
add_filter('template_include', function($default_template) {
if (is_post_type_archive('product')) {
$templatefilename = 'archive-product.php';
$template = WPVS_PATH . 'templates/' . $templatefilename;
$default_template = $template;
} else if ('product' == get_post_type() ) {
$templatefilename = 'single-product.php';
$template = WPVS_PATH . 'templates/' . $templatefilename;
$default_template = $template;
}
// Load new template also fallback if both condition fails load default
return $default_template;
}, 9999); // set priority, only if not worked with default one
The best option in this case is to provide a shortcode to the user. So they can place it on any page that they want (or that you auto generate). That way you will place your content inside their theme.
Something like this:
add_shortcode( 'slotsl-game', 'embed_game' );
/**
* Print the game
* #return false|string
*/
function embed_game(){
ob_start();
$game = get_post();
include_once SLOTSL_PLUGIN_DIR . 'templates/slotsl-single-game.php';
return ob_get_clean();
}
In my functions file I have this:
function caption_shortcode( $atts, $content = null ) {
return '<span class="caption">' . $content . '</span>';
}
add_shortcode( 'caption', 'caption_shortcode' );
In the CMS page editor I have this:
[caption]My Caption[/caption]
This page is utilizing a custom template file template-mypage.php. My question is: I would like to create multiple short codes types within the CMS such as:
[caption1]My Caption[/caption1]
[caption2]My Caption[/caption2]
[caption3]My Caption[/caption3]
then in my template-mypage.php... I would like to selectively choose where to place [caption1], [caption2], [caption3]... for example [caption1] will go somewhere on the top... [caption2] in the middle and [caption3] towards the bottom of the template-mypage.php, all seperated by some huge chunks of HTML content. I do not want to write any HTML within the WP CMS... all HTML should be written in the template-mypage.php.
Currently I believe WP limits shortcode output to come out of the_content(); Is it possible to do something like the_content_of_caption1(), the_content_of_caption2(), the_content_of_caption3()?
Thanks please let me know!
this product does this perfectly
http://wordpress.org/plugins/multiple-content-blocks/
I'm looking for a plugin (or better yet, not a plugin) for wordpress that lets me generate standard content elements, or includes for posts and pages.
For example, my_content_1 could be:
buy it now for $23!!
Which could then be included in posts and pages using some kind of syntax (or whatever) like:
Welcome to my site, blah blah blah.. check out this product - %my_content_1%
Not looking for anything fancy, anything that does this sort of thing would be awesome.
The point of this being much like a regular php include I could have the same information updated in one place and applied over many pages/posts.
I found something that is pretty much what I'm looking for:
http://wordpress.org/extend/plugins/reusables/
However, other suggestions would be good as I'm not too confident in the quality of the code for that plugin.
Not sure about a plugin, but how about simply creating something yourself? If you created a PHP page and set up variables such as
$content->title = "This is a title"
$content->smallText = "Insert some short paragraph here"
And then just include it in your header? You could store it in your theme directory and then call it like so
<?php $themeFolder = get_bloginfo("template_url"); ?>
<?php include($themeFolder."/content.php") ?>
Would that be suitable?
How about creating a few files and link them in using shortcode?
ie: open your themes/functions.php file add this..
<?php
function wp_my_shortcodes($atts)
{
extract(shortcode_atts(array(
'type' => '', //author, rss, adverts
), $atts));
switch($type) {
case 'author' : $display = wp_display_author_info(); break;
case 'rssview' : $display = wp_display_rss_info(); break;
case 'adverts' : $display = wp_display_adverts(); break;
default : $display = wp_display_author_info(); break;
}
return $display ;
}
add_shortcode('mycontent', wp_my_shortcodes);
function wp_display_author_info()
{
include(TEMPLATEPATH.'/my_author_info.php');
}
function wp_display_rss_info()
{
include(TEMPLATEPATH.'/my_rss_info.php');
}
function wp_display_adverts()
{
include(TEMPLATEPATH.'/my_adverts.php');
}
?>
using shortcodes inside your posts you can then bring in which ever piece of content that you want.. in the example above I've created 3 pages in the template root folder called
my_author_info.php, my_rss_info.php, my_adverts.php all of which speak for themself..
my_author_info.php
this page could use the the_author_meta() to populate a div box with included author info,
my_rss_info.php
include your subscription box to let users subscribe to your blog
my_adverts.php
include 4x 125x125 adverts?
so in the post i could use
[mycontent type='author']
[mycontent type='rssview']
[mycontent type='adverts']
if no argument is added to the shortcode then the default view is shown, in this case..
[mycontent]
would return the authorview as default...
this would then include that file in the content...
just remember to create the included files :)
I found something that is pretty much what I'm looking for:
http://wordpress.org/extend/plugins/reusables/