wp_get_post_categories() │ WP 2.1.0

Gets the list of post categories as an array.

This function is a wrapper for wp_get_object_terms() and is designed for abstraction away from the complexity of "WordPress taxonomy" concept.

No Hooks.

Return

Array|WP_Error. List of categories. If the $fields argument passed via $args is:

• all or all_with_object_id - an array of WP_Term objects will be returned.
• ids - an array of category IDs.
• names - an array of category names.
• WP_Error object if 'category' taxonomy doesn't exist.

Usage

wp_get_post_categories( $post_id, $args );

$post_id(int)

The Post ID. Does not default to the ID of the global $post.
Default: 0

$args(array)

Category query parameters.
Default: array()

$args Arguments

orderby(string)

By which criterion to sort the result. Could be:

• count - by number of posts;
• name - by name. (default);
• slug - by slug;
• none - output without sorting.

Default: 'name'

order(string)

Sort direction. ASC - in order, DESC - in reverse order.
Default: 'ASC'

fields(string)

Which fields to include in the resulting array. Could be:

• all - an array of WP_Term objects with all the information about each category;
• all_with_object_id - the same as all, plus term IDs;
• ids - get term IDs only;
• names - get term names only.

Default: 'ids'

Examples

#1 Demonstration of the function

This example shows the result of a basic use of this function:

$test = wp_get_post_categories( $post->ID );

print_r( $test );

/* Displays:
Array
(
	[0] => 1
	[1] => 2
)
*/

echo $test[1]; // Displays: 2

#2 Let's collect the categories information

The example below shows how to get the post categories and then collect the required data into the $cats array.

$post_categories = wp_get_post_categories( $post_id );

$cats = array();

foreach( $post_categories as $c ){

	$cat = get_category( $c );

	$cats[] = [ 'name' => $cat->name, 'slug' => $cat->slug ];
}

#3 Get all the data of the post categories

$test = wp_get_post_categories( $post->ID, [ 'fields' => 'all' ] );

print_r( $test );

/* Displays:
Array
(
	[0] => stdClass Object
		(
			[term_id] => 1
			[name] => No Category
			[slug] => no-category
			[term_group] => 0
			[term_taxonomy_id] => 1
			[taxonomy] => category
			[description] =>
			[parent] => 0
			[count] => 2
			[filter] => raw
		)

	[1] => stdClass Object
		(
			[term_id] => 2
			[name] => Some category
			[slug] => some-category
			[term_group] => 0
			[term_taxonomy_id] => 2
			[taxonomy] => category
			[description] =>
			[parent] => 0
			[count] => 1
			[filter] => raw
		)

)
*/

foreach( $test as $cat ){
	echo $cat->name .'<br>';
}

/* Displays:
No Category<br>
Some category<br>
*/