update_post_meta( int $post_id, string $meta_key, mixed $meta_value, mixed $prev_value =  ): int|bool

Updates a post meta field based on the given post ID.


Use the $prev_value parameter to differentiate between meta fields with the same key and post ID.

If the meta field for the post does not exist, it will be added and its ID returned.

Can be used in place of add_post_meta() .


Post ID.
Metadata key.
Metadata value. Must be serializable if non-scalar.
Previous value to check before updating.
If specified, only update existing metadata entries with this value. Otherwise, update all entries.



int|bool Meta ID if the key didn’t exist, true on successful update, false on failure or if the value passed to the function is the same as the one that is already in the database.

More Information

Character Escaping

Post meta values are passed through the stripslashes() function upon being stored, so you will need to be careful when passing in values (such as JSON) that might include \ escaped characters.

Do not store escaped values

Consider the JSON value {"key":"value with \"escaped quotes\""}

$escaped_json = '{"key":"value with \\"escaped quotes\\""}';
update_post_meta( $id, 'escaped_json', $escaped_json );
$broken = get_post_meta( $id, 'escaped_json', true );
$broken, after passing through stripslashes() ends up unparsable:
{"key":"value with "escaped quotes""}


By adding one more level of \ escaping using function wp_slash (introduced in WP 3.6), you can compensate for the call to stripslashes()

$escaped_json = '{"key":"value with \\"escaped quotes\\""}';
update_post_meta( $id, 'double_escaped_json', wp_slash( $escaped_json ) );
$fixed = get_post_meta( $id, 'double_escaped_json', true );
$fixed, after stripslashes(), ends up being stored as desired:
{"key":"value with \"escaped quotes\""}


function update_post_meta( $post_id, $meta_key, $meta_value, $prev_value = '' ) {
	// Make sure meta is updated for the post, not for a revision.
	$the_post = wp_is_post_revision( $post_id );
	if ( $the_post ) {
		$post_id = $the_post;

	return update_metadata( 'post', $post_id, $meta_key, $meta_value, $prev_value );



User Contributed Notes

  1. Skip to note 11 content

    ¡IMPORTANT If you are working with serialized data, the array is updated with an extra nested array
    In order to keep the same structure, update the Object in the 1rst nested position.

    $ticket_meta = get_post_meta($azgTorneoID,"mep_event_ticket_type",)
    $ticket_meta[0][0]["option_rsv_t"] = "9";
  2. Skip to note 12 content

    Other Examples
    Assuming a post has an ID of 76, and the following 4 custom fields:

    [key_1] => 'Happy'
    [key_1] => 'Sad'
    [key_2] => 'Gregory'
    [my_key] => 'Steve'

    To change key_2’s value to Hans:

    <?php update_post_meta( 76, 'key_2', 'Hans' ); ?>

    To change key_1’s value from Sad to Happy:

    <?php update_post_meta( 76, 'key_1', 'Happy', 'Sad' ); ?>

    The fields would now look like this:

    [key_1] => 'Happy'
    [key_1] => 'Happy'
    [key_2] => 'Hans'
    [my_key] => 'Steve'

    Note: This function will update only the first field that matches the criteria.

    To change the first key_1’s value from Happy to Excited:

    update_post_meta( 76, 'key_1', 'Excited', 'Happy' );
    update_post_meta( 76, 'key_1', 'Excited' );
    //To change all fields with the key "key_1":
    $key1_values = get_post_custom_values( 'key_1', 76 );
    foreach ( $key1_values as $value )
    	update_post_meta( 76, 'key_1', 'Excited', $value );

    Edit Page template


    For a more detailed example, go to the post_meta Functions Examples page.

  3. Skip to note 13 content

    Please note that if your database collation is case insensitive (as with suffix _ci) then update_post_meta() and delete_post_meta() and get_posts() will update/delete/query the meta records with keys that are upper or lower case. However get_post_meta() will be case sensitive due to WordPress caching. See https://core.trac.wordpress.org/ticket/18210 for more info.

You must log in before being able to contribute a note or feedback.