update_post_meta( int $post_id, string $meta_key, mixed $meta_value, mixed $prev_value = '' )

Update post meta field based on post ID.

Description

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.

Parameters

$post_id

(int) (Required) Post ID.

$meta_key

(string) (Required) Metadata key.

$meta_value

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

$prev_value

(mixed) (Optional) Previous value to check before removing.

Default value: ''

Return

(int|bool) Meta ID if the key didn't exist, true on successful update, false on failure.

Source

File: wp-includes/post.php 

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

	$updated = update_metadata( 'post', $post_id, $meta_key, $meta_value, $prev_value );
	if ( $updated ) {
		wp_cache_set( 'last_changed', microtime(), 'posts' );
	}
	return $updated;
}

Expand Source Code View on GitHub

Related

Uses

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

Update metadata for the specified object. If no value already exists for the specified object ID and metadata key, the metadata will be added.
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/rest-api/endpoints/class-wp-rest-attachments-controller.php: WP_REST_Attachments_Controller::create_item()

Creates a single attachment.
wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php: WP_REST_Attachments_Controller::update_item()

Updates a single attachment.
wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php: WP_REST_Posts_Controller::handle_template()

Sets the template for a post.
wp-includes/nav-menu.php: wp_update_nav_menu_item()

Save the properties of a menu item or create a new one.
wp-includes/class-wp-embed.php: WP_Embed::shortcode()

The do_shortcode() callback function.
wp-includes/user.php: _wp_privacy_account_request_confirmed()

Update log when privacy request is confirmed.
wp-includes/user.php: _wp_privacy_send_request_confirmation_notification()

Notify the site administrator via email when a request is confirmed.
wp-includes/user.php: _wp_privacy_send_erasure_fulfillment_notification()

Notify the user when their erasure request is fulfilled.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::dismiss_user_auto_draft_changesets()

Dismiss all of the current user’s auto-drafts (other than the present one).
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::import_theme_starter_content()

Import theme starter content into the customized state.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::set_changeset_lock()

Marks the changeset post as being currently edited by the current user.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::refresh_changeset_lock()

Refreshes changeset lock with the current time if current user edited the changeset before.
wp-includes/post.php: set_post_thumbnail()

Set a post thumbnail.
wp-includes/post.php: wp_update_attachment_metadata()

Update metadata for an attachment.
wp-includes/post.php: wp_insert_post()

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

Update attachment file path based on attachment ID.
wp-includes/revision.php: wp_restore_post_revision()

Restores a post to the specified revision.
wp-admin/custom-background.php: Custom_Background::handle_upload()

Handle an Image upload for the background image.
wp-admin/custom-background.php: Custom_Background::ajax_background_add()

Ajax handler for adding custom background context to an attachment.
wp-admin/custom-background.php: Custom_Background::wp_set_background_image()
wp-admin/custom-header.php: Custom_Image_Header::set_header_image()

Choose a header image, selected from existing uploaded and default headers, or provide an array of uploaded header data (either new, or from media library).
wp-admin/custom-header.php: Custom_Image_Header::ajax_header_add()

Given an attachment ID for a header image, updates its “last used” timestamp to now.
wp-admin/custom-header.php: Custom_Image_Header::customize_set_last_used()

Updates the last-used postmeta on a header image attachment after saving a new header image via the Customizer.
wp-admin/includes/image.php: wp_generate_attachment_metadata()

Generate post thumbnail attachment meta data.
wp-admin/includes/media.php: media_upload_form_handler()

Handles form submissions for the legacy media uploader.
wp-admin/includes/image-edit.php: wp_save_image()

Saves image to post along with enqueued changes in $_REQUEST[‘history’]
wp-admin/includes/image-edit.php: wp_restore_image()

Restores the metadata for a given attachment.
wp-admin/includes/ajax-actions.php: wp_ajax_wp_remove_post_lock()

Ajax handler for removing a post lock.
wp-admin/includes/ajax-actions.php: wp_ajax_save_attachment()

Ajax handler for updating attachment attributes.
wp-admin/includes/ajax-actions.php: wp_ajax_upload_attachment()

Ajax handler for uploading attachments
wp-admin/includes/user.php: _wp_privacy_completed_request()

Marks a request as completed by the admin and logs the current timestamp.
wp-admin/includes/file.php: wp_privacy_generate_personal_data_export_file()

Generate the personal data export file.
wp-admin/includes/file.php: wp_privacy_process_personal_data_export_page()

Intercept personal data exporter page ajax responses in order to assemble the personal data export file.
wp-admin/includes/post.php: wp_set_post_lock()

Mark the post as currently being edited by the current user
wp-admin/includes/post.php: edit_post()

Update an existing post with values provided in $_POST.
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Changelog

Changelog
Version Description
WP-1.5.0 Introduced.