wp_get_post_categories( int $post_id, array $args = array() ): array|WP_Error

Retrieve the list of categories for a post.


Description

Compatibility layer for themes and plugins. Also an easy layer of abstraction away from the complexity of the taxonomy layer.

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See also


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Parameters

$post_id int Optional
The Post ID. Does not default to the ID of the global $post. Default 0.
$args array Optional
Category query parameters.
See WP_Term_Query::__construct() for supported arguments.
More Arguments from WP_Term_Query::__construct( ... $query ) Array or query string of term query parameters.
  • taxonomystring|string[]
    Taxonomy name, or array of taxonomy names, to which results should be limited.
  • object_idsint|int[]
    Object ID, or array of object IDs. Results will be limited to terms associated with these objects.
  • orderbystring
    Field(s) to order terms by. Accepts:
    • Term fields ('name', 'slug', 'term_group', 'term_id', 'id', 'description', 'parent', 'term_order'). Unless $object_ids is not empty, 'term_order' is treated the same as 'term_id'.
    • 'count' to use the number of objects associated with the term.
    • 'include' to match the 'order' of the $include param.
    • 'slug__in' to match the 'order' of the $slug param.
    • 'meta_value'
    • 'meta_value_num'.
    • The value of $meta_key.
    • The array keys of $meta_query.
    • 'none' to omit the ORDER BY clause.
    Default 'name'.
  • orderstring
    Whether to order terms in ascending or descending order.
    Accepts 'ASC' (ascending) or 'DESC' (descending).
    Default 'ASC'.
  • hide_emptybool|int
    Whether to hide terms not assigned to any posts. Accepts 1|true or 0|false. Default 1|true.
  • includeint[]|string
    Array or comma/space-separated string of term IDs to include.
    Default empty array.
  • excludeint[]|string
    Array or comma/space-separated string of term IDs to exclude.
    If $include is non-empty, $exclude is ignored.
    Default empty array.
  • exclude_treeint[]|string
    Array or comma/space-separated string of term IDs to exclude along with all of their descendant terms. If $include is non-empty, $exclude_tree is ignored. Default empty array.
  • numberint|string
    Maximum number of terms to return. Accepts ''|0 (all) or any positive number. Default ''|0 (all). Note that $number may not return accurate results when coupled with $object_ids.
    See #41796 for details.
  • offsetint
    The number by which to offset the terms query.
  • fieldsstring
    Term fields to query for. Accepts:
    • 'all' Returns an array of complete term objects (WP_Term[]).
    • 'all_with_object_id' Returns an array of term objects with the 'object_id' param (WP_Term[]). Works only when the $object_ids parameter is populated.
    • 'ids' Returns an array of term IDs (int[]).
    • 'tt_ids' Returns an array of term taxonomy IDs (int[]).
    • 'names' Returns an array of term names (string[]).
    • 'slugs' Returns an array of term slugs (string[]).
    • 'count' Returns the number of matching terms (int).
    • 'id=>parent' Returns an associative array of parent term IDs, keyed by term ID (int[]).
    • 'id=>name' Returns an associative array of term names, keyed by term ID (string[]).
    • 'id=>slug' Returns an associative array of term slugs, keyed by term ID (string[]).
    Default 'all'.
  • countbool
    Whether to return a term count. If true, will take precedence over $fields. Default false.
  • namestring|string[]
    Name or array of names to return term(s) for.
  • slugstring|string[]
    Slug or array of slugs to return term(s) for.
  • term_taxonomy_idint|int[]
    Term taxonomy ID, or array of term taxonomy IDs, to match when querying terms.
  • hierarchicalbool
    Whether to include terms that have non-empty descendants (even if $hide_empty is set to true). Default true.
  • searchstring
    Search criteria to match terms. Will be SQL-formatted with wildcards before and after.
  • name__likestring
    Retrieve terms with criteria by which a term is LIKE $name__like.
  • description__likestring
    Retrieve terms where the description is LIKE $description__like.
  • pad_countsbool
    Whether to pad the quantity of a term's children in the quantity of each term's "count" object variable. Default false.
  • getstring
    Whether to return terms regardless of ancestry or whether the terms are empty. Accepts 'all' or '' (disabled). Default ''.
  • child_ofint
    Term ID to retrieve child terms of. If multiple taxonomies are passed, $child_of is ignored. Default 0.
  • parentint
    Parent term ID to retrieve direct-child terms of.
  • childlessbool
    True to limit results to terms that have no children.
    This parameter has no effect on non-hierarchical taxonomies.
    Default false.
  • cache_domainstring
    Unique cache key to be produced when this query is stored in an object cache. Default 'core'.
  • update_term_meta_cachebool
    Whether to prime meta caches for matched terms. Default true.
  • meta_keystring|string[]
    Meta key or keys to filter by.
  • meta_valuestring|string[]
    Meta value or values to filter by.
  • meta_comparestring
    MySQL operator used for comparing the meta value.
    See WP_Meta_Query::__construct() for accepted values and default value.
  • meta_compare_keystring
    MySQL operator used for comparing the meta key.
    See WP_Meta_Query::__construct() for accepted values and default value.
  • meta_typestring
    MySQL data type that the meta_value column will be CAST to for comparisons.
    See WP_Meta_Query::__construct() for accepted values and default value.
  • meta_type_keystring
    MySQL data type that the meta_key column will be CAST to for comparisons.
    See WP_Meta_Query::__construct() for accepted values and default value.
  • meta_queryarray
    An associative array of WP_Meta_Query arguments.
    See WP_Meta_Query::__construct() for accepted values.

Default: array()


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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. If $fields is 'ids', an array of category IDs. If $fields is 'names', an array of category names.
WP_Error object if 'category' taxonomy doesn't exist.


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More Information

The results from wp_get_post_categories() aren’t cached which will result in a database call being made every time this function is called. Use this function with care. For performance, functions like get_the_category() should be used to return categories attached to a post.


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Source

File: wp-includes/post.php. View all references

function wp_get_post_categories( $post_id = 0, $args = array() ) {
	$post_id = (int) $post_id;

	$defaults = array( 'fields' => 'ids' );
	$args     = wp_parse_args( $args, $defaults );

	$cats = wp_get_object_terms( $post_id, 'category', $args );
	return $cats;
}


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Changelog

Changelog
Version Description
2.1.0 Introduced.

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User Contributed Notes

  1. Skip to note 1 content
    Contributed by Codex

    The example below shows how categories are retrieved, and then additional information is retrieved for each category.

    $post_categories = wp_get_post_categories( $post_id );
    $cats = array();
    	
    foreach($post_categories as $c){
    	$cat = get_category( $c );
    	$cats[] = array( 'name' => $cat->name, 'slug' => $cat->slug );
    }
  2. Skip to note 2 content
    Contributed by Sabbir Hasan

    The example below shows how categories are retrieved, and using arguments additional info will be retrieved instead of calling get_category

    $post_categories = wp_get_post_categories( $post_id, array( 'fields' => 'all' ) );
    $cats = array();
    
    if( $post_categories ){ // Always Check before loop!
    	foreach($post_categories as $c){
    		$cats[] = array( 'name' => $c->name, 'slug' => $c->slug );
    		// Or we can just print it directly
    		printf("Category Name: %s, Category Slug: %s, Category Url: %s <br/>", $c->name, $c->slug, esc_url( get_category_link( $c->term_id ) ) );
    	}	
    }

    Only list Category names:

    $post_categories = wp_get_post_categories( $post_id, array( 'fields' => 'names' ) );
    
    if( $post_categories ){ // Always Check before loop!
    	foreach($post_categories as $name){
    		echo $name;
    	}
    }
  3. Skip to note 3 content
    Contributed by Akramul Hasan

    List category names in Descending order:

    $terms_list = wp_get_post_categories( $post_id, array( 'fields'=>'names', 'order'=> 'DESC' ) );
    if ( $terms_list ) { // Check $terms_list has value
    	foreach ( $terms_list as $term ) {
    		echo esc_html( $term ) . '<br />';
    	}
    }

    If you want to exclude any specific term from the list you can do like:

    // Add the 'exclude' key and put the term id you wanted to exclude from the result as key
    // If you want to exclude multiple terms, then put their keys separated by a comma or space
    
    $terms_list = wp_get_post_categories( $post_id, array( 'fields'=>'names', 'exclude'=> '1,7' ) );
    if ( $terms_list ) { // Check $terms_list has value
    	foreach ( $terms_list as $term ) {
    		echo esc_html( $term ) . '<br />';
    	}
    }

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