Hooks, In a Nutshell – WP Daily

I’ve published another article over on wpdaily.co exploring the concept of hooks. I remember when starting out that people kept mentioning hooks and filters and actions and… it took a while to grasp what they each meant. I think the first time I started to grasp it was when I read the codex and saw this:

You can sometimes accomplish the same goal with either an action or a filter. For example, if you want your plugin to change the text of a post, you might add an action function to publish_post (so the post is modified as it is saved to the database), or a filter function to the_content (so the post is modified as it is displayed in the browser screen).

And realized that actions and filters are each kinds of hooks. In the post I use a metaphor of procedural programming as people standing in a line waiting to register at the DMV. I hope it will help you understand hooks a little bit better. read it now at Hooks, In a Glorious Nutshell – WP Daily.

Add Parent Page Slug and Parent Template to WordPress Body Class

Add CSS body classes for the parent page on all child pages and the parent page template on of a WordPress site with this body_class filter. Ever need to style all child pages of a parent page in the same way or have you wanted to access every child page of a parent page via css selectors for styling? What about selecting all pages that are descendants of a page which is using a specific template?

body_classes_htmlBuilding large websites gets complicated, even in WordPress. Large sites usually mean there are many subpages and sections to the website that may need to be styled similarly. I’ve found it helpful to add a page’s parent page slug to the body class to allow me to alter or target the page or group of pages via css. By default the themes I’ve used have been generous in adding classes to the html body element for easy css selection rules. Things like the post slug, page template, logged in status, page vs post (or custom post type), post id, author… you get the idea. While half the time I don’t need half of this and the other half the time I find myself needing more.

Place this code into your functions.php file and your html body element will have a couple additional classes if they apply. It will have a class delineating the slug for the parent page on all child pages as well as a class delineating the template used by the parent page. This lets me apply styles to a whole sibling-section of a site pretty easily by just targeting the parent-slug on the body. Also adding the template of the parent in case I needed to use that.

post_parent_classesWalking through the code here we’re filtering the body_class function is how we are able to add this. We name our own function and give it a $classes parameter. Then throughout our function we can add classes to this $classes array and they will be output with the rest of the body classes. We need to hook into WordPress at the body_class function with add_filter and specify the hook and specify our own function to be called. In this case we grab the page properties of post_parent and the template of that parent. First set the post variable to reference the global scope, and then check to see if the post is a page with is_page. Then if the post object has a value for the parent (post_parent) we add the parent’s name to the classes array. Then we get the _wp_page_template meta data from the parent to find the template it’s using (if there is no template specified, then it returns default). This is added to our classes if it exists and then we return the classes array to the original body_class WP core function.

[cc lang=”php”]
/////////////////////////////////////////////////////////////////////////////////
// Body class adding page-parent
//
function cc_body_class( $classes ) {
global $post;
if ( is_page() ) {
// Has parent / is sub-page
if ( $post->post_parent ) {
# Parent post name/slug
$parent = get_post( $post->post_parent );
$classes[] = ‘parent-slug-‘.$parent->post_name;
// Parent template name
$parent_template = get_post_meta( $parent->ID, ‘_wp_page_template’, true);
if ( !empty($parent_template) )
$classes[] = ‘parent-template-‘.sanitize_html_class( str_replace( ‘.’, ‘-‘, $parent_template ), ” );
}
}
return $classes;
}
add_filter( ‘body_class’, ‘cc_body_class’ );
[/cc]

There are many more classes we can add to the body_class and like I said, sometimes you need more than what’s already provided and sometimes you need nothing. It all depends on the theme you’re using, what it provides and what your specific site and design require. What other classes have you wanted to see here? How have you filtered body_class to fit your site’s needs?

Set Default Terms for your Custom Taxonomies

Custom Taxonomy Default Term(s) for when it’s left blank

After looking through the WP codex and various plugins, I couldn’t find anywhere to set a custom taxonomy default term. WordPress has allowed us to create custom taxonomies for a while. Before we only had categories and tags hard coded in core. One feature from those days that didn’t seem to make it to the custom taxonomies of today is the possibility to select a default taxonomy term if none are selected. Did you know about this feature? Odds are you did, even if you didn’t realize it. Have you ever seen that ‘uncategorized’ category? That was the default category added for any content that didn’t have a specific category and was left, well, uncategorized.
uncategorized-default-post-category
An annoying feature if you weren’t expecting it, but nice to have if you took the moment to actually set up your default properly. I was working on a project recently with custom post types and custom taxonomies and suddenly needed this feature, but it didn’t seem to exist, so a few google’s later I found this nice snippet from Micheal Fields. Adopting the hook and adding some to allow for custom post types I wanted to share it here for my own safe keeping as well as the benefit of the community.

To Code Custom Taxonomy Default Terms

[cc lang=”php”]
/**
* Define default terms for custom taxonomies in WordPress 3.0.1
*
* @author Michael Fields http://wordpress.mfields.org/
* @props John P. Bloch http://www.johnpbloch.com/
* @props Evan Mulins https://circlecube.com/circlecube/
*
* @since 2010-09-13
* @alter 2013-01-31
*
* @license GPLv2
*/
function mfields_set_default_object_terms( $post_id, $post ) {
if ( ‘publish’ === $post->post_status && $post->post_type === ‘your_custom_post_type’ ) {
$defaults = array(
‘your_taxonomy_id’ => array( ‘your_term_slug’ )
//’your_taxonomy_id’ => array( ‘your_term_slug’, ‘your_term_slug’ )
);
$taxonomies = get_object_taxonomies( $post->post_type );
foreach ( (array) $taxonomies as $taxonomy ) {
$terms = wp_get_post_terms( $post_id, $taxonomy );
if ( empty( $terms ) && array_key_exists( $taxonomy, $defaults ) ) {
wp_set_object_terms( $post_id, $defaults[$taxonomy], $taxonomy );
}
}
}
}
add_action( ‘save_post’, ‘mfields_set_default_object_terms’, 100, 2 );
[/cc]
This code hooks to ‘save_post’ and fires when the post is saved. It will check the post status and only execute if the post status is set to publish. My addition will also check the post type against your custom post type. Then it sets the default for any taxonomy that you want to set a default for. Either a single term or multiple terms can be set as the default taxonomy term. If you want multiple default terms then you just use a comma separated list. This hook will then load the existing taxonomies and if they are not yet set on the post it will set them to your designated default(s). It’s nice and flexible as you can have multiple taxonomy defaults set quickly in the defaults array. Thanks Michael!

Set Default Terms for your Custom Taxonomies via Michael Fields » Set Default Terms for your Custom Taxonomies.