wp_set_post_terms( int $post_id, string|array $terms = , string $taxonomy = ‘post_tag’, bool $append = false ): array|false|WP_Error

Sets the terms for a post.


See also


The Post ID. Does not default to the ID of the global $post.
An array of terms to set for the post, or a string of terms separated by commas. Hierarchical taxonomies must always pass IDs rather than names so that children with the same names but different parents aren’t confused.


Taxonomy name. Default 'post_tag'.


If true, don’t delete existing terms, just add on. If false, replace the terms with the new terms.



array|false|WP_Error Array of term taxonomy IDs of affected terms. WP_Error or false on failure.


function wp_set_post_terms( $post_id = 0, $terms = '', $taxonomy = 'post_tag', $append = false ) {
	$post_id = (int) $post_id;

	if ( ! $post_id ) {
		return false;

	if ( empty( $terms ) ) {
		$terms = array();

	if ( ! is_array( $terms ) ) {
		$comma = _x( ',', 'tag delimiter' );
		if ( ',' !== $comma ) {
			$terms = str_replace( $comma, ',', $terms );
		$terms = explode( ',', trim( $terms, " \n\t\r\0\x0B," ) );

	 * Hierarchical taxonomies must always pass IDs rather than names so that
	 * children with the same names but different parents aren't confused.
	if ( is_taxonomy_hierarchical( $taxonomy ) ) {
		$terms = array_unique( array_map( 'intval', $terms ) );

	return wp_set_object_terms( $post_id, $terms, $taxonomy, $append );



User Contributed Notes

  1. Skip to note 4 content

    Non hierarchical term example

    For non-hierarchical terms (such as tags), you can pass either the term name or id. If you pass the id there is only one caveat: You must pass it as an integer, and it must be in an array. This is necessary because any non-array value passed will be converted to a string, which will be interpreted as a term name.

    $tag = '5'; // Wrong. This will add the tag with the *name* '5'.
    $tag = 5; // Wrong. This will also add the tag with the name '5'.
    $tag = array( '5' ); // Wrong. Again, this will be interpreted as a term name rather than an id.
    $tag = array( 5 ); // Correct. This will add the tag with the id 5.
    wp_set_post_terms( $post_id, $tag, $taxonomy );

    This function will only work on the native post type. For a taxonomy on a custom post type use wp_set_object_terms()

  2. Skip to note 5 content

    I do not know why, but you need to wrap your term_id in Array ((int) $ Term_id) – Then it will work as id … otherwise it is to create a term with name = $ Term_id

    $exchange = term_exists( $this->response['exchangeShortName'], 'exchange' );
    if ( ! $exchange ) {
        $exchange = wp_insert_term( $this->response['exchange'], 'exchange', array( 'slug' => $this->response['exchangeShortName'] ) );
    // create new term with name = $exchange['term_id'] - BUG?
    wp_set_post_terms( $this->postID, array( $exchange['term_id'] ), 'exchange', false ); 
    // It works fine, does not create a new term, and simply attaches the existing ID
    wp_set_post_terms( $this->postID, array( (int) $exchange['term_id'] ), 'exchange', false );
  3. Skip to note 6 content

    Hierarchical term example

    For hierarchical terms (such as categories), you must always pass the id rather than the term name to avoid confusion where there may be another child with the same name.

    To get the term id you can use:

    $term_id = term_exists( $term, $taxonomy, $parent );

    You may also need to pass by reference:

    wp_set_post_terms( $post_id, $term, &$taxonomy );

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