add_post_meta( int $post_id, string $meta_key, mixed $meta_value, bool $unique = false )

Add meta data field to a post.

Description

Post meta data is called "Custom Fields" on the Administration Screen.

Parameters

$post_id

(Required) Post ID.

$meta_key

(Required) Metadata name.

$meta_value

(Required) Metadata value. Must be serializable if non-scalar.

$unique

(Optional) Whether the same key should not be added.

Default value: false

Return

(int|false) Meta ID on success, false on failure.

Source

File: wp-includes/post.php 

function add_post_meta( $post_id, $meta_key, $meta_value, $unique = false ) {
	// Make sure meta is added to the post, not a revision.
	if ( $the_post = wp_is_post_revision($post_id) )
		$post_id = $the_post;

	$added = add_metadata( 'post', $post_id, $meta_key, $meta_value, $unique );
	if ( $added ) {
		wp_cache_set( 'last_changed', microtime(), 'posts' );
	}
	return $added;
}

Expand Source Code View on GitHub

Related

Uses

Uses
Uses Description
wp-includes/meta.php: add_metadata()

Add metadata for the specified object.
wp-includes/cache.php: wp_cache_set()

Saves the data to the cache.
wp-includes/revision.php: wp_is_post_revision()

Determines if the specified post is a revision.

Used By

Used By
Used By Description
wp-includes/class-wp-xmlrpc-server.php: wp_xmlrpc_server::add_enclosure_if_new()

Adds an enclosure to a post if it’s new.
wp-includes/class-wp-xmlrpc-server.php: wp_xmlrpc_server::set_custom_fields()

Set custom fields for post.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::trash_changeset_post()

Trash or delete a changeset post.
wp-includes/post.php: wp_add_trashed_suffix_to_post_name_for_post()

Adds a trashed suffix for a given post.
wp-includes/post.php: _publish_post_hook()

Hook to schedule pings and enclosures when a post is published.
wp-includes/post.php: wp_check_for_changed_slugs()

Check for changed slugs for published post objects and save the old slug.
wp-includes/post.php: wp_check_for_changed_dates()

Check for changed dates for published post objects and save the old date.
wp-includes/post.php: wp_trash_post()

Move a post or page to the Trash
wp-includes/post.php: wp_trash_post_comments()

Moves comments for a post to the trash.
wp-includes/post.php: wp_insert_post()

Insert or update a post.
wp-includes/functions.php: do_enclose()

Check content for video and audio links to add as enclosures.
wp-admin/includes/image.php: wp_generate_attachment_metadata()

Generate post thumbnail attachment meta data.
wp-admin/includes/misc.php: WP_Privacy_Policy_Content::_policy_page_updated()

Update the cached policy info when the policy page is updated.
wp-admin/includes/misc.php: WP_Privacy_Policy_Content::get_suggested_policy_text()

Check for updated, added or removed privacy policy information from plugins.
wp-admin/includes/post.php: wp_write_post()

Creates a new post from the “Write Post” form using $_POST information.
wp-admin/includes/post.php: add_meta()

Add post meta data defined in $_POST superglobal for post with given ID.
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Changelog

Changelog
Version Description
WP-1.5.0 Introduced.