Custom taxonomies in Wordpress - Step-by-Step Execution

Concept Flow - Custom taxonomies

Start: Define taxonomy args

↓

Call register_taxonomy()

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WordPress stores taxonomy

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Attach taxonomy to post types

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Use taxonomy in admin & front-end

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Add terms, assign to posts

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Query posts by taxonomy terms

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End

This flow shows how you define and register a custom taxonomy, attach it to post types, then use it to organize and query content.

Execution Sample

Wordpress

function create_genre_taxonomy() {
  register_taxonomy('genre', 'book', [
    'label' => 'Genre',
    'hierarchical' => true
  ]);
}
add_action('init', 'create_genre_taxonomy');

This code registers a hierarchical custom taxonomy 'genre' for the 'book' post type.

Execution Table

Step	Action	Function Call	Parameters	Result
1	Define function create_genre_taxonomy	N/A	N/A	Function ready to register taxonomy
2	Call register_taxonomy inside function	register_taxonomy	'genre', 'book', args	Taxonomy 'genre' registered for 'book'
3	Hook function to 'init' action	add_action	'init', 'create_genre_taxonomy'	Function will run on WordPress init
4	WordPress runs 'init' hook	create_genre_taxonomy	N/A	Taxonomy 'genre' is now active
5	Admin shows 'Genre' taxonomy for 'book'	N/A	N/A	User can add/edit 'genre' terms
6	Assign 'genre' terms to 'book' posts	N/A	N/A	Posts organized by genre
7	Query posts by 'genre' term	WP_Query	tax_query with 'genre'	Posts filtered by genre term
8	End	N/A	N/A	Custom taxonomy fully functional

💡 Process ends after taxonomy is registered, used in admin, and posts can be queried by it.

Variable Tracker

Variable	Start	After Step 2	After Step 4	Final
taxonomy 'genre'	undefined	registered	active	active and usable
function create_genre_taxonomy	undefined	defined	hooked to init	called on init

Key Moments - 3 Insights

Why do we hook the taxonomy registration function to 'init' instead of calling it directly?

WordPress needs taxonomies registered during initialization to properly set up. Hooking to 'init' ensures the taxonomy is registered at the right time, as shown in execution_table step 3 and 4.

What does 'hierarchical' => true mean in the taxonomy args?

It means the taxonomy behaves like categories with parent-child terms, not like tags. This affects how terms are displayed and organized, as seen in step 2 parameters.

How do we use the custom taxonomy after registering it?

After registration, WordPress shows it in admin for adding terms and assigning them to posts (step 5 and 6). Then you can query posts by taxonomy terms (step 7).

Visual Quiz - 3 Questions

Look at the execution table, at which step is the taxonomy 'genre' actually registered?

A Step 3

B Step 4

C Step 2

D Step 5

💡 Hint

Check the 'Result' column in step 2 where register_taxonomy is called.

According to variable_tracker, what is the state of 'taxonomy genre' after step 4?

A undefined

B active

C registered

D inactive

💡 Hint

Look at the 'After Step 4' column for 'taxonomy genre' in variable_tracker.

If we set 'hierarchical' => false in the args, how would the taxonomy behave?

A Like tags without hierarchy

B Like categories with parent-child terms

C It would not register

D It would register but not show in admin

💡 Hint

Refer to key_moments explanation about 'hierarchical' in step 2.

Concept Snapshot

Custom taxonomies organize content beyond default categories/tags.
Use register_taxonomy('name', 'post_type', args) inside a function.
Hook this function to 'init' to register at the right time.
Set 'hierarchical' true for category-like, false for tag-like.
After registering, add terms in admin and assign to posts.
Query posts by taxonomy terms using tax_query in WP_Query.

Full Transcript

Custom taxonomies in WordPress let you create new ways to group content. You write a function that calls register_taxonomy with a name, post type, and options like 'hierarchical'. This function is hooked to the 'init' action so WordPress runs it at the right time. Once registered, the taxonomy appears in the admin area where you can add terms and assign them to posts. You can then query posts filtered by these taxonomy terms. The key is registering during 'init' and choosing if the taxonomy is hierarchical (like categories) or not (like tags). This process helps organize content better and customize your site.