Extending Wordpress Capabilities With Custom Post Types, Taxonomies, And Fields

What are Custom Post Types, Taxonomies, and Fields

WordPress allows users to extend and customize its content management capabilities through the registration of custom post types, taxonomies, and fields. At a high level:

Custom post types – Enable creating custom content types beyond the built-in post and page. Examples are products, services, testimonials etc.
Custom taxonomies – Allow categorizing and tagging custom types. For example, product categories for products custom post type.
Custom fields – Allow storing additional metadata and attributes related to custom posts and taxonomies. For illustration, pricing details for products.

By leveraging these constructs, developers and site owners can add fully customized content entities and modeling to WordPress sites for capturing information beyond the typical blog posts and static pages. Some major benefits include:

Clean and consistent data modeling tailored to application needs
Custom presentation templates for surfacing content as needed for visitors
Extended custom functionality via hooks into register/save/render cycles
Streamlines capturing of niche information – e.g products catalog, real estate listings, job board etc.
Conventional admin UI provided for managing all custom entities

In summary, registering custom types and attributes unlocks greatly expanded data capabilities in WordPress, unlocking options for all kinds of purpose-built solutions.

Table of Contents

Registering Custom Post Types

New post types can be introduced by hooking into the init action and calling the register_post_type() function. For example, a basic “product” custom post type can be defined as follows:

add_action( 'init', 'register_product_cpt' );
  
function register_product_cpt() {

  $labels = array(
    'name' => 'Products',
    'singular_name' => 'Product'
  );

  $args = array(
     'labels' => $labels,
     'public' => true,
     'has_archive' => true,
     'rewrite' => array('slug' => 'products'),
     'show_in_rest' => true,
     'menu_icon' => 'dashicons-products',
  );
	
  register_post_type( 'product', $args );
}

Key details in the $args array include:

public – Allows product content to be viewable on the front end
rewrite slug – Pretty permalinks at example.com/products
has_archive – Archives of products accessible
show_in_rest – Allows API access via WP REST API
menu_icon – Icon shown in admin UI; dashicons used

With this basic registration, the WordPress administrator will then expose UI for creating and managing Product posts!

Adding Custom Taxonomies

Taxonomies allow annotating and categorizing post types. They enable capabilities like attaching terms and tags to posts, filtering by terms, and term archives. Examples are categories and tags for regular blog posts.

Custom taxonomies can hook into init similar to custom post types. To add a product category taxonomy for products:

         
add_action( 'init', 'register_product_taxonomy' );
      
function register_product_taxonomy() {

  $labels = array(
    'name' => 'Product Categories' 
  );
		   
  register_taxonomy(
    'product_category',
    'product',
    array(
      'label' => 'Product Categories',
      'labels' => $labels,
      'hierarchical' => true 
    )
  );

}

Alternatively, the taxonomy could be registered just for the ‘product’ post type using:

register_taxonomy_for_object_type( 'product_category', 'product' );

This automatically handles linking the taxonomy to the intended custom post type.

Implementing Custom Fields

Custom fields enable associating additional metadata and attributes to registered posts/pages and taxonomies. For example, products can track pricing, SKU, dimensions, and other product details via custom fields.

The register_meta() function hooks into the init action for defining additional fields. Example code for a basic product price field:

add_action( 'init', 'register_product_fields' );
	
function register_product_fields() {

  register_meta( 
    'product',
    'price',
    array(
      'type'          => 'string',
      'description'   => 'Price of the product',
      'single'        => true,
      'show_in_rest'  => true,
    )
  );

}

This allows setting and getting the ‘price’ custom field values on products using core APIs like update_post_meta() and get_post_meta(). The field appears as “Price” in the post editor.

The meta box UI can also be utilized for friendlier editing using:

add_action( 'add_meta_boxes', 'add_custom_product_fields' );
	
function add_custom_product_fields() {

  add_meta_box( 
    'product-fields',     
    'Product Fields',      
    'render_product_fields',
    'product',            
    'normal',              
    'high'
  );  

}  
		
function render_product_fields( $post ){
  
    wp_nonce_field( 'save_product_fields', 'product_fields_nonce' );
       
    // Render form inputs here 

}

This leverages a meta box during post creation/editing for managing the values.

Displaying Custom Content in Templates

For presentation on the front end, custom templates can utilize a set of template tags, conditionals, and functions for querying details of the custom posts. Some examples:

get_post_type() – Checks current post type inside The Loop
get_the_terms() – Retrieves attached terms
get_post_meta() – Gets values of custom fields
is_post_type_archive() – Conditionally show on archive pages

if( is_post_type_archive( 'product' ) ) {
	
 // Show product archive introp		
 
} 

if( get_post_type() == 'product' ) {

  $terms = get_the_terms( $post->ID, 'product_category' );
  
  $price = get_post_meta( $post->ID, 'price', true );
  
  // Output product specific template
  
}

These provide building blocks for crafting presentation templates around the custom types, taxonomy terms, and field attributes.

Advanced Customizations

Further customizations can tap deeper into the custom post lifecycles using dedicated hooks and filters provided through the post type, taxonomy, and metadata registration APIs.

Examples include:

Managing saved value sanitization and validation
Attaching capabilities required to create/edit
Customizing generated rewrite rules
Adding custom analytics or integration triggers

In addition, sites like the Plugin Developer Handbook offer a wealth of tutorials and examples for implementing advanced capabilities via custom code.

By tapping Register, Save, and Render cycle hooks, extremely customized post management functionality can be attained as needed.

Extending WordPress Capabilities With Custom Post Types, Taxonomies, And Fields