WordPress Primary Category

Select the primary category

https://wordpress.org/plugins/wp-primary-category

• Installation
• Settings
• Selecting
• Functions
• Filters
• Shortcode
• WP_Query
• REST API
• To Do

Installation

1. Copy the wp-primary-category folder into your wp-content/plugins folder
2. Activate the WordPress Primary Category plugin via the plugin admin page

Settings

How to able the primary category feature?

1. Open the settings page ( To open that page, we have to two alternatives );
2. Select the taxonomies what you want to able the feature;
3. After selected all taxonomies, click in the save button.

First Alternative: Settings > Primary Category

Second Alternative: Plugins admin page > Settings link in WordPress Primary Category

Settings Page

Selecting

After edit your settings, now you can select which will be your primaries categories.

Functions

Name	Argument(s)
get_primary_categories	mixed ( int, WP_Post, NULL ) $post required -- string $output default value: OBJECT others values: OBJECT, ARRAY_A, ARRAY_N or "ID" optional
get_primary_category	mixed ( int, WP_Term, object, string ) $taxonomy required -- mixed ( int, WP_Post, NULL ) $post default value: NULL optional -- string $output default value: OBJECT others values: OBJECT, ARRAY_A, ARRAY_N or "ID" optional
the_primary_category	mixed ( int, WP_Term, object, string ) $taxonomy required -- mixed ( int, WP_Post, NULL ) $post default value: NULL optional -- string $output default value: "link" others values: "name" optional-- string $echo default value: true optional
is_primary_category	mixed ( int, WP_Term, object ) $term required -- mixed ( string, NULL ) $taxonomy default value: NULL optional -- mixed ( int, WP_Post, NULL ) $post default value: NULL optional
has_primary_category	mixed ( int, WP_Post, NULL ) $post default value: NULL optional

Basic example

$args = array(
	'post_type' => 'book',
);

$query = new WP_Query( $args );
if ( $query->have_posts() ) {
	echo '<ul>';
	while ( $query->have_posts() ) {
		$query->the_post();
		echo '<li>' . get_the_title();
		if ( has_primary_category() ) {
			echo ' - ';
			the_primary_category( 'genre' );
		}
		echo '</li>';
	}
	echo '</ul>';
	wp_reset_postdata();
}

Filters

Filter	Argument(s)
wp_primary_category_update_option	array $data mixed ( array, boolean, NULL ) $option
wp_primary_category_option	array $data
wp_primary_category_not_allowed_post_types	array $post_types
wp_primary_category_post_types_args	array $args
wp_primary_category_post_types	mixed ( array, boolean ) $post_types
wp_primary_category_not_allowed_taxonomies	array $taxonomies
wp_primary_category_taxonomies_args	array $args
wp_primary_category_taxonomies	mixed ( array, boolean ) $taxonomies
wp_primary_category_html	string $html mixed ( int, WP_Term, object, string ) $taxonomy mixed ( int, WP_Post, NULL ) $post string $output
wp_primary_category_rest_api_output	string ( OBJECT, ARRAY_A, ARRAY_N or "ID" ) $output array $request
wp_primary_category_rest_api_data	array $data array $request

How to use the filters?

See bellow how to exclude page post type.

add_filter( 'wp_primary_category_post_types', function( $post_types ) {
	if ( isset( $post_types['page'] ) ) {
		unset( $post_types['page'] );
	}

	return $post_types;
} );

or

add_filter( 'wp_primary_category_not_allowed_post_types', function( $post_types ) {
	$post_types['page'] = 'page';

	return $post_types;
} );

Shortcode

Tag	Attribute(s)
the_primary_category	mixed ( int, WP_Term, object, string ) $taxonomy required -- mixed ( int, WP_Post, NULL ) $post default value: NULL optional -- string $output default value: "link" others values: "name" optional

How to use

[wp_primary_category taxonomy="genre"]

[wp_primary_category taxonomy="genre" post="1"]

[wp_primary_category taxonomy="genre" post="1" output="name"]

WP_Query

See below how get posts with genre primary category

$args = array(
	'post_type' => 'book',
	'meta_query' => array(
		array(
			'key'     => '_wp_primary_category_genre',
			'value'   => array( 2, 4 ), // terms id
			'compare' => 'IN',
		)
	),
);

$query = new WP_Query( $args );
if ( $query->have_posts() ) {
	while ( $query->have_posts() ) {
		$query->the_post();
		// your code here
	}
}

https://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters

REST API

Endpoint: /wp-json/wp/v2/posts/1

Default answer:

{
	"id": 1,
	"title": {
		"rendered": "Hello world!"
	},
	...
	"primary_categories": {
		"category": 1,
		"genre": 2
	},
	...
}

Use the filter below to change the answer:

add_filter( 'wp_primary_category_rest_api_data', function( $data ) {
	if ( isset( $data['genre'] ) ) {
		unset( $data['genre'] );
	}

	return $data;
} );

The new answer:

{
	"id": 1,
	"title": {
		"rendered": "Hello world!"
	},
	...
	"primary_categories": {
		"category": 1
	},
	...
}

Use the filter below to change the output:

add_filter( 'wp_primary_category_rest_api_output', function() {
	return OBJECT; // OBJECT, ARRAY_A, ARRAY_N or 'ID'
} );

The new answer:

{
	"id": 1,
	"title": {
		"rendered": "Hello world!"
	},
	...
	"primary_categories": {
		"category": {
			"term_id": 1,
			"name": "My category",
			"slug": "my-category",
			"term_group": 0,
			"term_taxonomy_id": 2,
			"taxonomy": "category",
			"description": "",
			"parent": 0,
			"count": 1,
			"filter": "raw"
		}
	},
	...
}

To Do

• add support to Gutenberg ( block editor )