Method by which plugins and themes extend core WordPress functionality.

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38
votes
6answers
8k views

Where can I find a list of WordPress hooks?

Where can I find a list of all the WordPress hooks and over-ridable functions (pluggable, scriptable, etc)? Edit: Plugin is listed here.
36
votes
4answers
13k views

Passing a parameter to filter and action functions

Is a way to pass my own parameters to the function in add_filter or add_action. For example take a look in the following code: function my_content($content, $my_param) { do something... using $...
36
votes
1answer
7k views

Where is the right place to register/enqueue scripts & styles

I am using WordPress 3.1.4 by now. I am confused with where (which hook) do I use: to register and/or enqueue scripts and styles on front- and back-ends? Questions: Which are right hooks to ...
32
votes
2answers
13k views

Difference Between Filter and Action Hooks?

I have been looking at the plugin API a bit more in depth recently and I was wondering what real differences there were between action and filter hooks. They both are events that receive data as a ...
17
votes
5answers
4k views

How do you use a CPT as the default home page?

I have a client who's site will be making heavy use of custom post types to configure their site. But I'm between a rock and a hard place for their requested home page. In reality, the home page ...
17
votes
1answer
10k views

how to limit search to post titles?

Is there a way to limit search to post titles? I know I can modify query.php core file but there must be a way to do it with hooks right? Thanks in advance!
17
votes
4answers
12k views

How to know what functions are hooked to an action/filter?

Is there a way to know what functions are hooked to a particular hook? For example if I'd like to know what functions are hooked to the wp_head hook.
16
votes
2answers
9k views

How to get WordPress' hook run sequence?

What is WordPress' hooks execution sequence? I mean, I want to know the order, how add_action hooks are executed, i.e. init wp_head wp_footer after_theme_setup and etc.. I want to know the ...
16
votes
3answers
2k views

How many times will this code run? (or, how rich is grandma?)

Hypothetical example but real world applicability (for someone learning, like me). Given this code: <?php function send_money_to_grandma() { internetofThings("send grandma","$1"); } ...
15
votes
2answers
25k views

WordPress hooks/filters insert before content or after title

trying to insert content before the post content in my functions.php - I know how to use the regular wp hooks, but unsure how to insert into other areas. Tried this, but it kills content on any other ...
15
votes
3answers
10k views

How to enqueue scripts on custom post add/edit pages?

I'm trying to enqueue a JS script only when someone is adding or editing a custom post type I created called "recipes". Currently the script works ok when I do this: if (is_admin()){ ...
14
votes
2answers
14k views

How to hook update_post_meta and delete_post_meta?

I'm still struggling to get my head around this whole hooking into things, so I'm really stuck on trying to do the following task: If update_post_meta is fired then check to see if the meta_key is ...
14
votes
2answers
1k views

How do filters and hooks really work in PHP

How does filters and hooks actually work in WordPress? I'm asking about something advanced. How is it implemented in PHP? E.g how does it collect all the hooks from the different plugins and "attach" ...
14
votes
2answers
13k views

Is there a hook that runs after a user logs in?

I am writing a plugin that fetches some extended user info from a remote service and I need it to execute its function each time a user logs in. Is there a hook that gets fired after login that I can ...
13
votes
3answers
6k views

Are there any hooks that alter the 404 logic?

Provided you have a 404 page defined in your theme, Wordpress will display a 404 page if "tag" is defined in $wp_query->query_vars, and there are no posts matching that tag. I'm writing a plugin that ...
13
votes
3answers
4k views

How to add Custom Blog Options to new blog setup form?

Seems like a simple enough requirement, but I'm struggling: I want to add an option field to the "Add New Site". A simple text option is fine. How do I do this? I need to save this custom blog ...
12
votes
2answers
8k views

Save_post for custom post type?

Is there a save_post hook for custom post types? example: save_my_post_type I know there is publish_my_post_type but I'm looking for a save hook.
12
votes
3answers
2k views

get_template_part vs action hooks in themes

It seems to me both of these afford the opportunity for the end user to modify a theme without actually editing the themes files (via child themes). My question is, is one method preferred over the ...
12
votes
4answers
1k views

Hooking in to plugins

I'm working on a plugin that would ideally be able to do things when a user does something through a different plugin. I can add custom hooks in those plugins but obviously this wouldn't work well ...
12
votes
6answers
3k views

How to include code only on specific pages?

I'm learning about plugins and shortcodes. I noticed that when I activate my plugin its code gets loaded on all of my pages-- even pages that don't have my shortcode. (I don't mean content vs. admin ...
11
votes
2answers
5k views

Why do some hooks not work inside class context?

I'm pretty stumped on this one. I'm using add_action inside my plugin class to do certain things- add scripts & styles to the head, wp_ajax, etc. Here's the actions, in the __construct: function ...
10
votes
1answer
885 views

Changing the “Plugin Activated” Message Default

Whenever an administrator in WordPress activates a plugin, upon the reload of the plugin page, a notice will appear upon successful activation reporting "Plugin Activated". Is there a way to change ...
10
votes
2answers
600 views

Hierarchical taxonomy UI

I don't like the way the taxonomies are displayed within the Wordpress admin and was wondering if anyone knew the best way to hook in and change it. Currently if I select some terms within my post ...
10
votes
2answers
11k views

Difference between do_action and add_action

This question might be wrong, I am not sure about it. Because I am not clear on this. I know add_action it is used to to hook our function to the specified function. For example add_action('wp_head'.'...
9
votes
5answers
9k views

Theme Activate Hook

I would like to write a function to email me the URL of the website when my theme is activated. What is the hook initiated when the theme is activated?
9
votes
2answers
8k views

Use wp init hook to call other hooks?

I want to know if it is a good practice according to WordPress theme or plugin development. add_action('init','all_my_hooks'); function all_my_hooks(){ // some initialization stuff here and then ...
9
votes
3answers
146 views

Generate dormant hook references

It seems a lot of plugin developers take the time to add filter/action hooks to let users tweak their products’ functionality. Which is great, but what they often don’t do is provide a list of hooks ...
9
votes
4answers
2k views

Move excerpt meta box to above content editor

I found a WordPress hook called "edit_form_after_title" to add a text box after the title. How can I use this hook to display the excerpt after the title while creating a new post?
9
votes
2answers
173 views

What is “all” in isset($wp_filter['all])

I'm a newbie in WordPress. I'm trying to understand how it generates the XHTML pages. I guess it's the function of do_action( 'hook-name' ) , but I'm stuck with the understanding of the instruction ...
9
votes
2answers
2k views

Registering Class methods as hook callbacks

I'm not sure if I have done this correctly. As I understand it: if I have a class foo and a static method bar I can register that as the callback by passing the array array("foo","bar") as the ...
8
votes
2answers
11k views

Trouble understanding apply_filters()

In apply_filters() apply_filters( $tag, $value, $var ... ); I'm having trouble wrapping my head around the $value and $var. I read the codex and it sounds like the $value can be modified, $var not, ...
8
votes
4answers
270 views

Is it possible to completely stop WP_Query retrieving posts?

I'm trying to use WP Redis to cache entire $wp_query object with key is $query_vars_hash. This is how $wp_query was added to $wp_object_cache: add_action('wp', function($wp) { if ( is_admin() ) ...
8
votes
2answers
34k views

How to customize woocommerce related products? [closed]

I have the following lines of code in my website that will display the related products at the bottom of my single product page in WooCommerce... functions.php: // display upsells and related ...
8
votes
3answers
19k views

Hook for post and page load

I need to run a function when a particular post or page is loaded. Is there any hook that lets me check whether a post is being displayed during page load ?
8
votes
1answer
125 views

Add a new tab to Wordpress Plugin install Listing

When an user searches for a plugin from the WP Admin's Add Plugin area, I want to add a new tab(with a link to a page) next to the current tabs. The location where I want the link is marked in the ...
8
votes
1answer
1k views

Whats worth using add_action when we can simply use add_filter?

I've just looked into wordpress code and found this definition of add_action: function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) { return add_filter($tag, $...
7
votes
3answers
17k views

Is there a way to send HTML formatted emails with Wordpress' wp_mail function?

Is there an action_hook or something similar that could help me achieve this? I tried adding markup in a PHP string variable and just fired off an email with the wp_mail function like so: $email_to =...
7
votes
2answers
4k views

How do I implement the WordPress Iris picker into my plugin on the front-end?

This question here is asking the same question as I am, but there were no adequate answers nor a selected correct answer so I am asking again hoping if I ask in a more coherent manner I might get a ...
7
votes
5answers
7k views

Is there a way to set default custom fields when creating a post?

When I'm creating a new post, just after clicking "Add New", when the post editor shows, instead of having to use the dropdown and choose a custom field to use, I'd like to have some default custom ...
7
votes
1answer
101 views

Hook that get's triggered when the author of a post is changed

Is there any hook that gets trigged when the author of a post is modified from the edit post screen? I can list to the update post hook, but then I will not know whether the author of the post was ...
7
votes
2answers
856 views

Wordpress and event-driven programming - what is it about?

I want to state very clearly that this does not intend to revive the discussion about functional/procedural programming versus object-oriented programming. There is plenty said about that, on WPSE and ...
7
votes
2answers
171 views

Better to fire specific hooks or generic hooks with parameters?

I'm creating a form plugin to handle forms that can be hooked into using actions/filters by developers. My plug-in needs to be able to handle different forms with different sets of filters and I see ...
7
votes
1answer
230 views

What is the difference between update_post_meta and update_postmeta hooks?

I am working on an enhanced revisioning system, to create a log file for all changes made by users and/or algorithms concerning metadata attached to specific post types. While I am perfectly aware ...
6
votes
4answers
6k views

Import Wordpress XML File from Within Functions.php

I am developing a theme which has a different method of adding in content and so, the default install of Wordpress won't show any content because of this. I was wondering if it is possible to ...
6
votes
3answers
6k views

Which hook should be used to add an action containing a redirect?

I want to build a plugin that grabs certain url params from the query string to build a new query string for the same page. I'm following the excellent the Professional WordPress Plugin Development ...
6
votes
4answers
3k views

Is there a limit to hook priority?

When I wish my filter or action hook to override all others, I will assign it a priority of 999. However, lately I have been seeing some people use extreme values for the priority, such as 20000, and ...
6
votes
2answers
2k views

Action hook for custom tax edit

So, i have a function in my template file functions.php which cache a search form that contain a custom taxonomie terms. I want to flush cache (or delete one cache group) when I add/delete/edit terms ...
6
votes
4answers
7k views

Auto-retrieve YouTube Image for Thumbnail?

I have a custom post type that accepts a YouTube embed HTML snippet, title, and a featured image. Currently, I'm going and finding an image for the featured image, but ideally I would be able to ...
6
votes
2answers
157 views

Valid characters for actions, hooks and filters

I haven't ever seen a tag such as do_action('something_10'). Is it invalid if I use numbers? If the method is valid, how can I write different numbers in the tag string conditionally? For example, is ...
6
votes
2answers
3k views

Earliest hook to reliably get $post/$posts

What's the earliest possible action I can hook into where I'll be able to access the global $post/$posts variables on both the front and back ends? I've tried looking through the Codex reference, Adam ...