get_terms( array|string $args = array(), array|string $deprecated =  ): WP_Term[]|int[]|string[]|string|WP_Error

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

Description

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

The return type varies depending on the value passed to $args['fields']. See WP_Term_Query::get_terms() for details. In all cases, a WP_Error object will be returned if an invalid taxonomy is requested.

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.

Taxonomy or an array of taxonomies should be passed via the ‘taxonomy’ argument in the $args array:

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

Prior to 4.5.0, taxonomy was passed as the first parameter of get_terms().

Parameters

$argsarray|stringoptional
Array or string of arguments. See WP_Term_Query::__construct() for information on accepted arguments.

Default:array()

$deprecatedarray|stringoptional
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:''

Return

WP_Term[]|int[]|string[]|string|WP_Error Array of terms, a count thereof as a numeric string, or WP_Error if any of the taxonomies do not exist.
See the function description for more information.

Source

function get_terms( $args = array(), $deprecated = '' ) {
	$term_query = new WP_Term_Query();

	$defaults = array(
		'suppress_filter' => false,
	);

	/*
	 * 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)
	 */
	$_args          = wp_parse_args( $args );
	$key_intersect  = array_intersect_key( $term_query->query_var_defaults, (array) $_args );
	$do_legacy_args = $deprecated || empty( $key_intersect );

	if ( $do_legacy_args ) {
		$taxonomies       = (array) $args;
		$args             = wp_parse_args( $deprecated, $defaults );
		$args['taxonomy'] = $taxonomies;
	} else {
		$args = wp_parse_args( $args, $defaults );
		if ( isset( $args['taxonomy'] ) && null !== $args['taxonomy'] ) {
			$args['taxonomy'] = (array) $args['taxonomy'];
		}
	}

	if ( ! empty( $args['taxonomy'] ) ) {
		foreach ( $args['taxonomy'] as $taxonomy ) {
			if ( ! taxonomy_exists( $taxonomy ) ) {
				return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
			}
		}
	}

	// Don't pass suppress_filter to WP_Term_Query.
	$suppress_filter = $args['suppress_filter'];
	unset( $args['suppress_filter'] );

	$terms = $term_query->query( $args );

	// Count queries are not filtered, for legacy reasons.
	if ( ! is_array( $terms ) ) {
		return $terms;
	}

	if ( $suppress_filter ) {
		return $terms;
	}

	/**
	 * Filters the found terms.
	 *
	 * @since 2.3.0
	 * @since 4.6.0 Added the `$term_query` parameter.
	 *
	 * @param array         $terms      Array of found terms.
	 * @param array|null    $taxonomies An array of taxonomies if known.
	 * @param array         $args       An array of get_terms() arguments.
	 * @param WP_Term_Query $term_query The WP_Term_Query object.
	 */
	return apply_filters( 'get_terms', $terms, $term_query->query_vars['taxonomy'], $term_query->query_vars, $term_query );
}

Hooks

apply_filters( ‘get_terms’, array $terms, array|null $taxonomies, array $args, WP_Term_Query $term_query )

Filters the found terms.

Changelog

VersionDescription
4.8.0Introduced 'suppress_filter' parameter.
4.5.0Changed 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.
4.4.0Introduced 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.
4.2.0Introduced 'name' and 'childless' parameters.
2.3.0Introduced.

User Contributed Notes

  1. Skip to note 25 content

    All get_terms attributes with default values:
    (I try default from this article and it didn’t work. This works.)

    $get_terms_default_attributes = array (
    			'taxonomy' => 'category', //empty string(''), false, 0 don't work, and return empty array
    			'orderby' => 'name',
    			'order' => 'ASC',
    			'hide_empty' => true, //can be 1, '1' too
    			'include' => 'all', //empty string(''), false, 0 don't work, and return empty array
    			'exclude' => 'all', //empty string(''), false, 0 don't work, and return empty array
    			'exclude_tree' => 'all', //empty string(''), false, 0 don't work, and return empty array
    			'number' => false, //can be 0, '0', '' too
    			'offset' => '',
    			'fields' => 'all',
    			'name' => '',
    			'slug' => '',
    			'hierarchical' => true, //can be 1, '1' too
    			'search' => '',
    			'name__like' => '',
    			'description__like' => '',
    			'pad_counts' => false, //can be 0, '0', '' too
    			'get' => '',
    			'child_of' => false, //can be 0, '0', '' too
    			'childless' => false,
    			'cache_domain' => 'core',
    			'update_term_meta_cache' => true, //can be 1, '1' too
    			'meta_query' => '',
    			'meta_key' => array(),
    			'meta_value'=> '',
    	);
  2. Skip to note 26 content

    As of WordPress 4.6.1, here’s the array that’s returned (to add to Leo’s helpful note above)

    array(1) {
      [0]=>
      object(WP_Term) (11) {
        ["term_id"]=>  //int
        ["name"]=>	//string 
        ["slug"]=>  //string 
        ["term_group"]=>  //int
        ["term_taxonomy_id"]=> //int
        ["taxonomy"]=>	//string
        ["description"]=>	//string
        ["parent"]=>	//int
        ["count"]=>	// int
        ["filter"]=>	//string
        ["meta"]=> array(0) { // presumably this would be some returned meta-data?
        }
      }
    }
  3. Skip to note 28 content

    Get categories and subcategories by custom taxonomies:

    $taxonomies = get_terms( array(
    	'taxonomy' => 'taxonomy_name',
    	'hide_empty' => false
    ) );
    
    if ( !empty($taxonomies) ) :
    	$output = '<select>';
    	foreach( $taxonomies as $category ) {
    		if( $category->parent == 0 ) {
    			$output.= '<optgroup label="'. esc_attr( $category->name ) .'">';
    			foreach( $taxonomies as $subcategory ) {
    				if($subcategory->parent == $category->term_id) {
    				$output.= '<option value="'. esc_attr( $subcategory->term_id ) .'">
    					'. esc_html( $subcategory->name ) .'</option>';
    				}
    			}
    			$output.='</optgroup>';
    		}
    	}
    	$output.='</select>';
    	echo $output;
    endif;
  4. Skip to note 29 content

    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 (·):

    $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;
    }
  5. Skip to note 30 content

    Working with Advanced Custom Fields (field type: Taxonomy, output: Object) for filtering taxonomies.

    Case: Create a filter with main categories defined by ACF field, and all another should belongs to *others*.

    Solution:

    // Define Featured Category IDs first
    $featured_category_ids = array();
    // It must be output WP_Object
    $featured_categories = get_field('main_category_filters');
    
    // Creating loop to insert IDs to array.
    foreach( $featured_categories as $cat ) {
    	$featured_category_ids[] = $cat-&gt;term_id;
    }
    
    // Now, if Featured Categories are match, add their IDs via 'exclude'
    if( $featured_categories ) {
    	$args = array(
    		'taxonomy' =&gt; 'event_cat',
    		'parent' =&gt; 0,
    		'exclude' =&gt; $featured_category_ids
    	);
    } else {
        // If no featured, just display all terms
    	$args = array(
    		'taxonomy' =&gt; 'event_cat',
    		'parent' =&gt; 0
    	);
    }
    
    // Starting query terms now
    $other_categories = get_terms($args);
  6. Skip to note 33 content

    Meta Query using a custom field, and then ordering using a different custom field.

    $terms = get_terms( array(
        'taxonomy' => 'tax_slug',
        'hide_empty' => false,
        'meta_query' => array(
            [
                'key' => 'meta_key_slug_1',
                'value' => 'desired value to look for'
            ]
        ),
        'meta_key' => 'meta_key_slug_2',
        'orderby' => 'meta_key_slug_2'
    
    ) );
  7. Skip to note 35 content

    If `get_terms` doesnt works for some odd reason with custom taxonomy not showing registered, try using `WP_Term_Query`:

    $term_query = new WP_Term_Query( array( 
        'taxonomy' => 'regions', // <-- Custom Taxonomy name..
        'orderby'                => 'name',
        'order'                  => 'ASC',
        'child_of'               => 0,
        'parent'                 => 0,
        'fields'                 => 'all',
        'hide_empty'             => false,
    ) );
    
    // Show Array info
    echo '<pre>';
    print_r( $term_query->terms );
    echo '</pre>';
    
    
    //Render html
    if ( ! empty( $term_query->terms ) ) {
        foreach ( $term_query->terms as $term ) {
            echo wp_kses_post( $term->name ) . ", ";
            echo esc_html( $term->term_id ) . ", ";
            echo esc_html( $term->slug ) . ", ";
            echo "<br>";
        }
    } else {
        echo 'No term found.';
    }

    Get all args from here: https://developer.wordpress.org/reference/classes/WP_Term_Query/__construct/

  8. Skip to note 36 content

    Custom Taxonomy and Sub Category Lists.
    Your can use this to create list table also.

    $taxonomies = get_terms( array(
        'taxonomy' => 'product_cat', //Custom taxonomy name
        'hide_empty' => false
    ) );
    if ( !empty($taxonomies) ) :
        foreach( $taxonomies as $category ) {
            if( $category->parent == 0 ) {
                
                //remove uncategorized from loop
                if( $category->slug == 'uncategorized' ){
                    continue;
                }
    
                //Parent category information
     			echo esc_html__($category->name, 'text-domain');
     			echo esc_html__($category->description, 'text-domain');
     			echo esc_html__($category->slug, 'text-domain');
     			echo esc_html__($category->count, 'text-domain');
    
    
     			//Sub category information
    	        foreach( $taxonomies as $subcategory ) {
    	            if($subcategory->parent == $category->term_id) {
    			        echo esc_html__($subcategory->name, 'text-domain');
    			        echo esc_html__($subcategory->description, 'text-domain');
    			        echo esc_html__($subcategory->slug, 'text-domain');
    			        echo esc_html__($subcategory->count, 'text-domain');
    	            }
    	        }
    
            }
        }
    endif;
  9. Skip to note 37 content

    If you want to `get_terms() ` by `post_type`, here’s a way to do it:

    // First, get the post IDs
    $my_ids = get_posts(
        array(
            'post_type' => 'my_post_type',
            'posts_per_page' => -1,
            'fields' => 'ids',
        )
    );
    
    // Then pass the the array of IDs to get_terms()
    $terms = get_terms(
        array(
            'taxonomy' => 'my_taxonomy',
            'object_ids' => $my_ids,
            'hide_empty' => true,
        )
    );
  10. Skip to note 39 content

    Get All Terms id and name in a array for make dropdown select:

    function custom_get_term_lit( $taxonomy = 'category' ) {
        $terms = get_terms( [
            'taxonomy'   => $taxonomy,
            'hide_empty' => false,
        ] );
        if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {
            return wp_list_pluck( $terms, 'name', 'term_id' );
        }
        return false;
    }
    
    $category = custom_get_term_lit('custom-taxonomy-id');
    echo "<select name='category' id='category-dropdown'>";
    foreach ( $category as $cat_id => $cat_name ) {
        echo "<option value='" . esc_attr( $cat_id ) . "'>" . esc_html__( $cat_name, 'text-domain' ) . "</option>";
    }
    echo "</select>";
  11. Skip to note 40 content

    list categories( or custom taxonomy ) and subcategory in organazid way

            
            //parent category (then child(category) and subchild, then posts in each category ) 
            $parent_ID = 0; 
            
            //-level_one_clilds-
            $level_one_clilds = get_terms( array(
                'taxonomy'   => 'lecture_category',
                'parent'     => $parent_ID ,
                'depth'      => 1,
                'hide_empty' => false
            ) );
            foreach( $level_one_clilds as $level_one_clild ):
                
                echo $level_one_clild->name . "<hr>" ;
                
                //--level_tow_clilds--
                $level_tow_clilds = get_terms( array(
                  'taxonomy'    => 'lecture_category',
                  'parent'      => $level_one_clild->term_id, 
                  'depth'       => 1,
                  'hide_empty'  => false
                ));
                foreach( $level_tow_clilds as $level_tow_clild ):
                  echo "- " . $level_tow_clild->name . "<hr>" ;
                  
                   //---level_three_clild ---
                   $level_three_clilds = get_terms( array(
                    'taxonomy'    => 'lecture_category',
                    'parent'      => $level_tow_clild->term_id, 
                    'depth'       => 1,
                    'hide_empty'  => false
                  ));
                  foreach( $level_three_clilds as $level_three_clild ):
                    echo "-- " . $level_three_clild->name . "<hr>" ;
                  endforeach ; //level_three_clild
                  
                endforeach ;  //level_tow_clild
                
            endforeach ; //level_one_clilds
            
  12. Skip to note 41 content

    If you have a term assigned to something else than a post, here is a warning:
    'hide_empty' is default true so it only shows terms assigned to posts. So if you get an empty Array returned be aware that terms (e.g. categories) assigned to attachments for example are not shown by default unless you use 'hide_empty' => false:

    $wpdocs_categories = get_terms( array(
    	'taxonomy' => 'category',
    	'hide_empty' => false,
    	'name__like' => 'foo'
    ) );
  13. Skip to note 42 content

    Be very careful as the code below:

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

    can return valid terms, but can also return a WP_Error if, for example, the taxonomy is invalid…

    Therefore this check alone isn’t enough to save you from bugs in your code:

       
    if ( ! empty( $terms ) ) {
        // whatever code
    }

    Instead, better to use the one below:

    if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {
        // whatever code
    }
  14. Skip to note 43 content

    Categories and Tags are the two pre-defined Taxonomies. The Taxonomy Name, when included as an element ‘taxonomy’ of the array specified as the first parameter $args, has a value of ‘category’ for Categories and ‘post_tag’ for Tags.
    'taxonomy' => 'category'
    'taxonomy' => 'post_tag'

  15. Skip to note 44 content

    As per https://core.trac.wordpress.org/ticket/41813 if you use this to in combination with a custom taxonomy which is used for media/attachments. You may find that all works well except the count of the terms when using get_terms ( which returns nothing ).

    To fix this you may need to use this call in register_taxonomy
    'update_count_callback' => '_update_generic_term_count',
    ( https://core.trac.wordpress.org/ticket/41813#comment:8 )

  16. Skip to note 45 content

    Loop through taxonomy and list all subcategories.

        $taxonomy = 'my_taxonomy';
    
        function listTaxonomies($taxonomy,$term_id = '0') {
            $output = '';
    
            $args = array(
                'taxonomy' => $taxonomy,
                'parent' => $term_id
            );
            $categories = get_terms($args);
    
            if($categories) {
    			$output.= '<div style="padding-left:2em;">';
                foreach( $categories as $category ) {
                    $output.= esc_attr( $category->name ) . ' (' . $category->slug . ')<br>';
                    $output.= listTaxonomies($taxonomy,$category->term_id);
                }
    			$output.= '</div>';
            }
            return $output;
        }
    
        listTaxonomies($taxonomy);
  17. Skip to note 46 content

    Get all child taxonomy of a parent taxonomy

    function get_child_taxonomies( $taxonomy_name, $termId, $args = array() ) {
    	$defaults = array(
    		'taxonomy'   => $taxonomy_name,
    		'orderby'    => 'name',
    		'order'      => 'ASC',
    		'hide_empty' => true,
    		'child_of'   => $termId,
    	);
    
    	$args       = wp_parse_args( $args, $defaults );
    	$taxonomies = get_terms( $args );
    
    	if ( empty( $taxonomies ) || is_wp_error( $taxonomies ) ) {
    		return false;
    	}	
    	return $taxonomies;
    
    }
  18. Skip to note 47 content

    Get Terms filtered by first letter

    $authors = get_terms('book-authors', array('name__like' => $first_l));
    
    function custom_tax_query( $pieces, $taxonomies, $args ) {
      if ( 'book-authors' == $taxonomies[0] ) {
        $pieces['where'] = str_replace("LIKE '%", "LIKE '", $pieces['where']);
      }
    return $pieces;
    }

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