get_terms ( array|string $args = array(), array $deprecated = '' )

Retrieve the terms in a given taxonomy or list of taxonomies.

You can fully inject any customizations to the query before it is sent, as well as control the output with a filter.

The ‘get_terms’ filter will be called when the cache has the term and will pass the found term along with the array of $taxonomies and array of $args. This filter is also called before the array of terms is passed and will pass the array of terms, along with the $taxonomies and $args.

The ‘list_terms_exclusions’ filter passes the compiled exclusions along with the $args.

The ‘get_terms_orderby’ filter passes the ORDER BY clause for the query along with the $args array.

Prior to 4.5.0, the first parameter of get_terms() was a taxonomy or list of taxonomies:

$terms = get_terms( 'post_tag', array(
    'hide_empty' => false,
) );

Since 4.5.0, taxonomies should be passed via the ‘taxonomy’ argument in the $args array:

$terms = get_terms( array(
    'taxonomy' => 'post_tag',
    'hide_empty' => false,
) );

Return: (array|int|WP_Error) List of WP_Term instances and their children. Will return WP_Error, if any of $taxonomies do not exist.

Source file: wp-includes/taxonomy.php

View source


Parameters

$args

(array|string) (Optional) Array or string of arguments to get terms.

  • 'taxonomy'
    (string|array) Taxonomy name, or array of taxonomies, to which results should be limited.
  • 'orderby'
    (string) Field(s) to order terms by. Accepts term fields ('name', 'slug', 'term_group', 'term_id', 'id', 'description'), 'count' for term taxonomy count, 'include' to match the 'order' of the $include param, 'meta_value', 'meta_value_num', the value of $meta_key, the array keys of $meta_query, or 'none' to omit the ORDER BY clause. Defaults to 'name'.
  • 'order'
    (string) Whether to order terms in ascending or descending order. Accepts 'ASC' (ascending) or 'DESC' (descending). Default 'ASC'.
  • 'hide_empty'
    (bool|int) Whether to hide terms not assigned to any posts. Accepts 1|true or 0|false. Default 1|true.
  • 'include'
    (array|string) Array or comma/space-separated string of term ids to include.
  • 'exclude'
    (array|string) Array or comma/space-separated string of term ids to exclude. If $include is non-empty, $exclude is ignored.
  • 'exclude_tree'
    (array|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.
  • 'number'
    (int|string) Maximum number of terms to return. Accepts ''|0 (all) or any positive number. Default ''|0 (all).
  • 'offset'
    (int) The number by which to offset the terms query.
  • 'fields'
    (string) Term fields to query for. Accepts 'all' (returns an array of complete term objects), 'ids' (returns an array of ids), 'id=>parent' (returns an associative array with ids as keys, parent term IDs as values), 'names' (returns an array of term names), 'count' (returns the number of matching terms), 'id=>name' (returns an associative array with ids as keys, term names as values), or 'id=>slug' (returns an associative array with ids as keys, term slugs as values). Default 'all'.
  • 'name'
    (string|array) Optional. Name or array of names to return term(s) for.
  • 'slug'
    (string|array) Optional. Slug or array of slugs to return term(s) for.
  • 'hierarchical'
    (bool) Whether to include terms that have non-empty descendants (even if $hide_empty is set to true). Default true.
  • 'search'
    (string) Search criteria to match terms. Will be SQL-formatted with wildcards before and after.
  • 'name__like'
    (string) Retrieve terms with criteria by which a term is LIKE $name__like.
  • 'description__like'
    (string) Retrieve terms where the description is LIKE $description__like.
  • 'pad_counts'
    (bool) Whether to pad the quantity of a term's children in the quantity of each term's "count" object variable. Default false.
  • 'get'
    (string) Whether to return terms regardless of ancestry or whether the terms are empty. Accepts 'all' or empty (disabled).
  • 'child_of'
    (int) Term ID to retrieve child terms of. If multiple taxonomies are passed, $child_of is ignored. Default 0.
  • 'parent'
    (int|string) Parent term ID to retrieve direct-child terms of.
  • 'childless'
    (bool) True to limit results to terms that have no children. This parameter has no effect on non-hierarchical taxonomies. Default false.
  • 'cache_domain'
    (string) Unique cache key to be produced when this query is stored in an object cache. Default is 'core'.
  • 'update_term_meta_cache'
    (bool) Whether to prime meta caches for matched terms. Default true.
  • 'meta_query'
    (array) Meta query clauses to limit retrieved terms by. See WP_Meta_Query.
  • 'meta_key'
    (string) Limit terms to those matching a specific metadata key. Can be used in conjunction with $meta_value.
  • 'meta_value'
    (string) Limit terms to those matching a specific metadata value. Usually used in conjunction with $meta_key.

Default value: array()

$deprecated

(array) (Optional) Argument array, when using the legacy function parameter format. If present, this parameter will be interpreted as $args, and the first function parameter will be parsed as a taxonomy or array of taxonomies.

Default value: ''


Used by

Uses


Source

function get_terms( $args = array(), $deprecated = '' ) {
	global $wpdb;

	$defaults = array(
		'taxonomy'               => null,
		'orderby'                => 'name',
		'order'                  => 'ASC',
		'hide_empty'             => true,
		'include'                => array(),
		'exclude'                => array(),
		'exclude_tree'           => array(),
		'number'                 => '',
		'offset'                 => '',
		'fields'                 => 'all',
		'name'                   => '',
		'slug'                   => '',
		'hierarchical'           => true,
		'search'                 => '',
		'name__like'             => '',
		'description__like'      => '',
		'pad_counts'             => false,
		'get'                    => '',
		'child_of'               => 0,
		'parent'                 => '',
		'childless'              => false,
		'cache_domain'           => 'core',
		'update_term_meta_cache' => true,
		'meta_query'             => ''
	);

	/*
	 * Legacy argument format ($taxonomy, $args) takes precedence.
	 *
	 * We detect legacy argument format by checking if
	 * (a) a second non-empty parameter is passed, or
	 * (b) the first parameter shares no keys with the default array (ie, it's a list of taxonomies)
	 */
	$key_intersect  = array_intersect_key( $defaults, (array) $args );
	$do_legacy_args = $deprecated || empty( $key_intersect );

	$taxonomies = null;
	if ( $do_legacy_args ) {
		$taxonomies = (array) $args;
		$args = $deprecated;
	} elseif ( isset( $args['taxonomy'] ) && null !== $args['taxonomy'] ) {
		$taxonomies = (array) $args['taxonomy'];
		unset( $args['taxonomy'] );
	}

	$empty_array = array();

	if ( $taxonomies ) {
		foreach ( $taxonomies as $taxonomy ) {
			if ( ! taxonomy_exists($taxonomy) ) {
				return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy' ) );
			}
		}
	}

	/**
	 * Filter the terms query default arguments.
	 *
	 * Use 'get_terms_args' to filter the passed arguments.
	 *
	 * @since 4.4.0
	 *
	 * @param array $defaults   An array of default get_terms() arguments.
	 * @param array $taxonomies An array of taxonomies.
	 */
	$args = wp_parse_args( $args, apply_filters( 'get_terms_defaults', $defaults, $taxonomies ) );

	$args['number'] = absint( $args['number'] );
	$args['offset'] = absint( $args['offset'] );

	// Save queries by not crawling the tree in the case of multiple taxes or a flat tax.
	$has_hierarchical_tax = false;
	if ( $taxonomies ) {
		foreach ( $taxonomies as $_tax ) {
			if ( is_taxonomy_hierarchical( $_tax ) ) {
				$has_hierarchical_tax = true;
			}
		}
	}

	if ( ! $has_hierarchical_tax ) {
		$args['hierarchical'] = false;
		$args['pad_counts'] = false;
	}

	// 'parent' overrides 'child_of'.
	if ( 0 < intval( $args['parent'] ) ) {
		$args['child_of'] = false;
	}

	if ( 'all' == $args['get'] ) {
		$args['childless'] = false;
		$args['child_of'] = 0;
		$args['hide_empty'] = 0;
		$args['hierarchical'] = false;
		$args['pad_counts'] = false;
	}

	/**
	 * Filter the terms query arguments.
	 *
	 * @since 3.1.0
	 *
	 * @param array $args       An array of get_terms() arguments.
	 * @param array $taxonomies An array of taxonomies.
	 */
	$args = apply_filters( 'get_terms_args', $args, $taxonomies );

	// Avoid the query if the queried parent/child_of term has no descendants.
	$child_of = $args['child_of'];
	$parent   = $args['parent'];

	if ( $child_of ) {
		$_parent = $child_of;
	} elseif ( $parent ) {
		$_parent = $parent;
	} else {
		$_parent = false;
	}

	if ( $_parent ) {
		$in_hierarchy = false;
		foreach ( $taxonomies as $_tax ) {
			$hierarchy = _get_term_hierarchy( $_tax );

			if ( isset( $hierarchy[ $_parent ] ) ) {
				$in_hierarchy = true;
			}
		}

		if ( ! $in_hierarchy ) {
			return $empty_array;
		}
	}

	$_orderby = strtolower( $args['orderby'] );
	if ( 'count' == $_orderby ) {
		$orderby = 'tt.count';
	} elseif ( 'name' == $_orderby ) {
		$orderby = 't.name';
	} elseif ( 'slug' == $_orderby ) {
		$orderby = 't.slug';
	} elseif ( 'include' == $_orderby && ! empty( $args['include'] ) ) {
		$include = implode( ',', array_map( 'absint', $args['include'] ) );
		$orderby = "FIELD( t.term_id, $include )";
	} elseif ( 'term_group' == $_orderby ) {
		$orderby = 't.term_group';
	} elseif ( 'description' == $_orderby ) {
		$orderby = 'tt.description';
	} elseif ( 'none' == $_orderby ) {
		$orderby = '';
	} elseif ( empty( $_orderby ) || 'id' == $_orderby || 'term_id' === $_orderby ) {
		$orderby = 't.term_id';
	} else {
		$orderby = 't.name';
	}

	/**
	 * Filter the ORDERBY clause of the terms query.
	 *
	 * @since 2.8.0
	 *
	 * @param string $orderby    `ORDERBY` clause of the terms query.
	 * @param array  $args       An array of terms query arguments.
	 * @param array  $taxonomies An array of taxonomies.
	 */
	$orderby = apply_filters( 'get_terms_orderby', $orderby, $args, $taxonomies );

	$order = strtoupper( $args['order'] );
	if ( ! empty( $orderby ) ) {
		$orderby = "ORDER BY $orderby";
	} else {
		$order = '';
	}

	if ( '' !== $order && ! in_array( $order, array( 'ASC', 'DESC' ) ) ) {
		$order = 'ASC';
	}

	$where_conditions = array();

	if ( $taxonomies ) {
		$where_conditions[] = "tt.taxonomy IN ('" . implode("', '", array_map( 'esc_sql', $taxonomies ) ) . "')";
	}

	$exclude = $args['exclude'];
	$exclude_tree = $args['exclude_tree'];
	$include = $args['include'];

	$inclusions = '';
	if ( ! empty( $include ) ) {
		$exclude = '';
		$exclude_tree = '';
		$inclusions = implode( ',', wp_parse_id_list( $include ) );
	}

	if ( ! empty( $inclusions ) ) {
		$where_conditions[] = 't.term_id IN ( ' . $inclusions . ' )';
	}

	$exclusions = array();
	if ( ! empty( $exclude_tree ) ) {
		$exclude_tree = wp_parse_id_list( $exclude_tree );
		$excluded_children = $exclude_tree;
		foreach ( $exclude_tree as $extrunk ) {
			$excluded_children = array_merge(
				$excluded_children,
				(array) get_terms( $taxonomies[0], array( 'child_of' => intval( $extrunk ), 'fields' => 'ids', 'hide_empty' => 0 ) )
			);
		}
		$exclusions = array_merge( $excluded_children, $exclusions );
	}

	if ( ! empty( $exclude ) ) {
		$exclusions = array_merge( wp_parse_id_list( $exclude ), $exclusions );
	}

	// 'childless' terms are those without an entry in the flattened term hierarchy.
	$childless = (bool) $args['childless'];
	if ( $childless ) {
		foreach ( $taxonomies as $_tax ) {
			$term_hierarchy = _get_term_hierarchy( $_tax );
			$exclusions = array_merge( array_keys( $term_hierarchy ), $exclusions );
		}
	}

	if ( ! empty( $exclusions ) ) {
		$exclusions = 't.term_id NOT IN (' . implode( ',', array_map( 'intval', $exclusions ) ) . ')';
	} else {
		$exclusions = '';
	}

	/**
	 * Filter the terms to exclude from the terms query.
	 *
	 * @since 2.3.0
	 *
	 * @param string $exclusions `NOT IN` clause of the terms query.
	 * @param array  $args       An array of terms query arguments.
	 * @param array  $taxonomies An array of taxonomies.
	 */
	$exclusions = apply_filters( 'list_terms_exclusions', $exclusions, $args, $taxonomies );

	if ( ! empty( $exclusions ) ) {
		// Must do string manipulation here for backward compatibility with filter.
		$where_conditions[] = preg_replace( '/^\s*AND\s*/', '', $exclusions );
	}

	if ( ! empty( $args['name'] ) ) {
		$names = (array) $args['name'];
		foreach ( $names as &$_name ) {
			// `sanitize_term_field()` returns slashed data.
			$_name = stripslashes( sanitize_term_field( 'name', $_name, 0, reset( $taxonomies ), 'db' ) );
		}

		$where_conditions[] = "t.name IN ('" . implode( "', '", array_map( 'esc_sql', $names ) ) . "')";
	}

	if ( ! empty( $args['slug'] ) ) {
		if ( is_array( $args['slug'] ) ) {
			$slug = array_map( 'sanitize_title', $args['slug'] );
			$where_conditions[] = "t.slug IN ('" . implode( "', '", $slug ) . "')";
		} else {
			$slug = sanitize_title( $args['slug'] );
			$where_conditions[] = "t.slug = '$slug'";
		}
	}

	if ( ! empty( $args['name__like'] ) ) {
		$where_conditions[] = $wpdb->prepare( "t.name LIKE %s", '%' . $wpdb->esc_like( $args['name__like'] ) . '%' );
	}

	if ( ! empty( $args['description__like'] ) ) {
		$where_conditions[] = $wpdb->prepare( "tt.description LIKE %s", '%' . $wpdb->esc_like( $args['description__like'] ) . '%' );
	}

	if ( '' !== $parent ) {
		$parent = (int) $parent;
		$where_conditions[] = "tt.parent = '$parent'";
	}

	$hierarchical = $args['hierarchical'];
	if ( 'count' == $args['fields'] ) {
		$hierarchical = false;
	}
	if ( $args['hide_empty'] && !$hierarchical ) {
		$where_conditions[] = 'tt.count > 0';
	}

	$number = $args['number'];
	$offset = $args['offset'];

	// Don't limit the query results when we have to descend the family tree.
	if ( $number && ! $hierarchical && ! $child_of && '' === $parent ) {
		if ( $offset ) {
			$limits = 'LIMIT ' . $offset . ',' . $number;
		} else {
			$limits = 'LIMIT ' . $number;
		}
	} else {
		$limits = '';
	}

	if ( ! empty( $args['search'] ) ) {
		$like = '%' . $wpdb->esc_like( $args['search'] ) . '%';
		$where_conditions[] = $wpdb->prepare( '((t.name LIKE %s) OR (t.slug LIKE %s))', $like, $like );
	}

	// Meta query support.
	$join = '';
	$distinct = '';

	$mquery = new WP_Meta_Query();
	$mquery->parse_query_vars( $args );
	$mq_sql = $mquery->get_sql( 'term', 't', 'term_id' );
	$meta_clauses = $mquery->get_clauses();

	if ( ! empty( $meta_clauses ) ) {
		$join .= $mq_sql['join'];
		$where_conditions[] = preg_replace( '/^\s*AND\s*/', '', $mq_sql['where'] );
		$distinct .= "DISTINCT";

		// 'orderby' support.
		$allowed_keys = array();
		$primary_meta_key   = null;
		$primary_meta_query = reset( $meta_clauses );
		if ( ! empty( $primary_meta_query['key'] ) ) {
			$primary_meta_key = $primary_meta_query['key'];
			$allowed_keys[] = $primary_meta_key;
		}
		$allowed_keys[] = 'meta_value';
		$allowed_keys[] = 'meta_value_num';
		$allowed_keys   = array_merge( $allowed_keys, array_keys( $meta_clauses ) );

		if ( ! empty( $args['orderby'] ) && in_array( $args['orderby'], $allowed_keys ) ) {
			switch( $args['orderby'] ) {
				case $primary_meta_key:
				case 'meta_value':
					if ( ! empty( $primary_meta_query['type'] ) ) {
						$orderby = "ORDER BY CAST({$primary_meta_query['alias']}.meta_value AS {$primary_meta_query['cast']})";
					} else {
						$orderby = "ORDER BY {$primary_meta_query['alias']}.meta_value";
					}
					break;

				case 'meta_value_num':
					$orderby = "ORDER BY {$primary_meta_query['alias']}.meta_value+0";
					break;

				default:
					if ( array_key_exists( $args['orderby'], $meta_clauses ) ) {
						// $orderby corresponds to a meta_query clause.
						$meta_clause = $meta_clauses[ $args['orderby'] ];
						$orderby = "ORDER BY CAST({$meta_clause['alias']}.meta_value AS {$meta_clause['cast']})";
					}
					break;
			}
		}
	}

	$selects = array();
	switch ( $args['fields'] ) {
		case 'all':
			$selects = array( 't.*', 'tt.*' );
			break;
		case 'ids':
		case 'id=>parent':
			$selects = array( 't.term_id', 'tt.parent', 'tt.count', 'tt.taxonomy' );
			break;
		case 'names':
			$selects = array( 't.term_id', 'tt.parent', 'tt.count', 't.name', 'tt.taxonomy' );
			break;
		case 'count':
			$orderby = '';
			$order = '';
			$selects = array( 'COUNT(*)' );
			break;
		case 'id=>name':
			$selects = array( 't.term_id', 't.name', 'tt.count', 'tt.taxonomy' );
			break;
		case 'id=>slug':
			$selects = array( 't.term_id', 't.slug', 'tt.count', 'tt.taxonomy' );
			break;
	}

	$_fields = $args['fields'];

	/**
	 * Filter the fields to select in the terms query.
	 *
	 * Field lists modified using this filter will only modify the term fields returned
	 * by the function when the `$fields` parameter set to 'count' or 'all'. In all other
	 * cases, the term fields in the results array will be determined by the `$fields`
	 * parameter alone.
	 *
	 * Use of this filter can result in unpredictable behavior, and is not recommended.
	 *
	 * @since 2.8.0
	 *
	 * @param array $selects    An array of fields to select for the terms query.
	 * @param array $args       An array of term query arguments.
	 * @param array $taxonomies An array of taxonomies.
	 */
	$fields = implode( ', ', apply_filters( 'get_terms_fields', $selects, $args, $taxonomies ) );

	$join .= " INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id";

	$where = implode( ' AND ', $where_conditions );

	$pieces = array( 'fields', 'join', 'where', 'distinct', 'orderby', 'order', 'limits' );

	/**
	 * Filter the terms query SQL clauses.
	 *
	 * @since 3.1.0
	 *
	 * @param array $pieces     Terms query SQL clauses.
	 * @param array $taxonomies An array of taxonomies.
	 * @param array $args       An array of terms query arguments.
	 */
	$clauses = apply_filters( 'terms_clauses', compact( $pieces ), $taxonomies, $args );

	$fields = isset( $clauses[ 'fields' ] ) ? $clauses[ 'fields' ] : '';
	$join = isset( $clauses[ 'join' ] ) ? $clauses[ 'join' ] : '';
	$where = isset( $clauses[ 'where' ] ) ? $clauses[ 'where' ] : '';
	$distinct = isset( $clauses[ 'distinct' ] ) ? $clauses[ 'distinct' ] : '';
	$orderby = isset( $clauses[ 'orderby' ] ) ? $clauses[ 'orderby' ] : '';
	$order = isset( $clauses[ 'order' ] ) ? $clauses[ 'order' ] : '';
	$limits = isset( $clauses[ 'limits' ] ) ? $clauses[ 'limits' ] : '';

	if ( $where ) {
		$where = "WHERE $where";
	}

	$query = "SELECT $distinct $fields FROM $wpdb->terms AS t $join $where $orderby $order $limits";

	// $args can be anything. Only use the args defined in defaults to compute the key.
	$key = md5( serialize( wp_array_slice_assoc( $args, array_keys( $defaults ) ) ) . serialize( $taxonomies ) . $query );
	$last_changed = wp_cache_get( 'last_changed', 'terms' );
	if ( ! $last_changed ) {
		$last_changed = microtime();
		wp_cache_set( 'last_changed', $last_changed, 'terms' );
	}
	$cache_key = "get_terms:$key:$last_changed";
	$cache = wp_cache_get( $cache_key, 'terms' );
	if ( false !== $cache ) {
		if ( 'all' === $_fields ) {
			$cache = array_map( 'get_term', $cache );
		}

		/**
		 * Filter the given taxonomy's terms cache.
		 *
		 * @since 2.3.0
		 *
		 * @param array $cache      Cached array of terms for the given taxonomy.
		 * @param array $taxonomies An array of taxonomies.
		 * @param array $args       An array of get_terms() arguments.
		 */
		return apply_filters( 'get_terms', $cache, $taxonomies, $args );
	}

	if ( 'count' == $_fields ) {
		return $wpdb->get_var( $query );
	}

	$terms = $wpdb->get_results($query);
	if ( 'all' == $_fields ) {
		update_term_cache( $terms );
	}

	// Prime termmeta cache.
	if ( $args['update_term_meta_cache'] ) {
		$term_ids = wp_list_pluck( $terms, 'term_id' );
		update_termmeta_cache( $term_ids );
	}

	if ( empty($terms) ) {
		wp_cache_add( $cache_key, array(), 'terms', DAY_IN_SECONDS );

		/** This filter is documented in wp-includes/taxonomy.php */
		return apply_filters( 'get_terms', array(), $taxonomies, $args );
	}

	if ( $child_of ) {
		foreach ( $taxonomies as $_tax ) {
			$children = _get_term_hierarchy( $_tax );
			if ( ! empty( $children ) ) {
				$terms = _get_term_children( $child_of, $terms, $_tax );
			}
		}
	}

	// Update term counts to include children.
	if ( $args['pad_counts'] && 'all' == $_fields ) {
		foreach ( $taxonomies as $_tax ) {
			_pad_term_counts( $terms, $_tax );
		}
	}

	// Make sure we show empty categories that have children.
	if ( $hierarchical && $args['hide_empty'] && is_array( $terms ) ) {
		foreach ( $terms as $k => $term ) {
			if ( ! $term->count ) {
				$children = get_term_children( $term->term_id, $term->taxonomy );
				if ( is_array( $children ) ) {
					foreach ( $children as $child_id ) {
						$child = get_term( $child_id, $term->taxonomy );
						if ( $child->count ) {
							continue 2;
						}
					}
				}

				// It really is empty.
				unset($terms[$k]);
			}
		}
	}

	$_terms = array();
	if ( 'id=>parent' == $_fields ) {
		foreach ( $terms as $term ) {
			$_terms[ $term->term_id ] = $term->parent;
		}
	} elseif ( 'ids' == $_fields ) {
		foreach ( $terms as $term ) {
			$_terms[] = $term->term_id;
		}
	} elseif ( 'names' == $_fields ) {
		foreach ( $terms as $term ) {
			$_terms[] = $term->name;
		}
	} elseif ( 'id=>name' == $_fields ) {
		foreach ( $terms as $term ) {
			$_terms[ $term->term_id ] = $term->name;
		}
	} elseif ( 'id=>slug' == $_fields ) {
		foreach ( $terms as $term ) {
			$_terms[ $term->term_id ] = $term->slug;
		}
	}

	if ( ! empty( $_terms ) ) {
		$terms = $_terms;
	}

	// Hierarchical queries are not limited, so 'offset' and 'number' must be handled now.
	if ( $hierarchical && $number && is_array( $terms ) ) {
		if ( $offset >= count( $terms ) ) {
			$terms = array();
		} else {
			$terms = array_slice( $terms, $offset, $number, true );
		}
	}

	wp_cache_add( $cache_key, $terms, 'terms', DAY_IN_SECONDS );

	if ( 'all' === $_fields ) {
		$terms = array_map( 'get_term', $terms );
	}

	/** This filter is documented in wp-includes/taxonomy.php */
	return apply_filters( 'get_terms', $terms, $taxonomies, $args );
}


Changelog

  • Since: WordPress 2.3.0
  • Since: WordPress 4.2.0 Introduced 'name' and 'childless' parameters.
  • Since: WordPress 4.4.0 Introduced the ability to pass 'term_id' as an alias of 'id' for the orderby parameter. Introduced the 'meta_query' and 'update_term_meta_cache' parameters. Converted to return a list of WP_Term objects.
  • Since: WordPress 4.5.0 Changed the function signature so that the $args array can be provided as the first parameter. Introduced 'meta_key' and 'meta_value' parameters. Introduced the ability to order results by metadata.

User Contributed Notes

  1. Get all post categories ordered by count.

    String syntax:

    $categories = get_terms( 'category', 'orderby=count&hide_empty=0' );
    

    Array syntax:

    $categories = get_terms( 'category', array(
     	'orderby'    => 'count',
     	'hide_empty' => 0
    ) );
    
  2. Get all post categories ordered by count.

    String syntax:

    $categories = get_terms( 'category', 'orderby=count&hide_empty=0' );
    

    Array syntax:

    $categories = get_terms( 'category', array(
    	'orderby'    => 'count',
    	'hide_empty' => 0,
    ) );
    

    Get all the links categories:

    $my_links_categories = get_terms( 'link_category', 'orderby=count&hide_empty=0' );
    

    List all the terms in a custom taxonomy, without a link:

    $terms = get_terms( 'my_taxonomy' );
    if ( ! empty( $terms ) && ! is_wp_error( $terms ) ){
    	echo '<ul>';
    	foreach ( $terms as $term ) {
    		echo '<li>' . $term->name . '</li>';
    	}
    	echo '</ul>';
    }
    

    List all the terms, with link to term archive, separated by an interpunct (ยท):

    $args = array( 'hide_empty=0' );
    
    $terms = get_terms( 'my_term', $args );
    if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {
    	$count = count( $terms );
    	$i = 0;
    	$term_list = '<p class="my_term-archive">';
    	foreach ( $terms as $term ) {
    		$i++;
    		$term_list .= '<a href="' . esc_url( get_term_link( $term ) ) . '" alt="' . esc_attr( sprintf( __( 'View all post filed under %s', 'my_localization_domain' ), $term->name ) ) . '">' . $term->name . '</a>';
    		if ( $count != $i ) {
    			$term_list .= ' &middot; ';
    		}
    		else {
    			$term_list .= '</p>';
    		}
    	}
    	echo $term_list;
    }
    
  3. The array this pushes back, follows the following structure:


    array(
    [0] => WP_Term Object
    (
    [term_id] =>
    [name] =>
    [slug] =>
    [term_group] =>
    [term_taxonomy_id] =>
    [taxonomy] =>
    [description] =>
    [parent] =>
    [count] =>
    [filter] =>
    )

  4. If parent => 0 is passed, only top-level terms will be returned

    $terms = get_terms( array( 
        'taxonomy' => 'tax_name',
        'parent'   => 0
    ) );
    

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