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

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

Contents

Description 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 and its ID returned.

Can be used in place of add_post_meta().

Parameters 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 updating.

Default value: ''

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Return Return

(int|bool) The new meta field ID if a field with the given key didn't exist and was therefore added, true on successful update, false on failure.

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Source 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.
	$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 );
}

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Changelog Changelog

Changelog
Version Description
1.5.0 Introduced.

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Uses Uses

Uses
Uses Description
wp-includes/revision.php: wp_is_post_revision()

Determines if the specified post is a revision.
wp-includes/meta.php: update_metadata()

Updates metadata for the specified object. If no value already exists for the specified object ID and metadata key, the metadata will be added.

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Used By Used By

Used By
Used By Description
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-admin/includes/privacy-tools.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/privacy-tools.php: wp_privacy_generate_personal_data_export_file()

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

Marks a request as completed by the admin and logs the current timestamp.
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/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/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-admin/includes/class-custom-background.php: Custom_Background::ajax_background_add()

Ajax handler for adding custom background context to an attachment.
wp-admin/includes/image-edit.php: wp_restore_image()

Restores the metadata for a given attachment.
wp-admin/includes/image-edit.php: wp_save_image()

Saves image to post, along with enqueued changes in $_REQUEST['history'].
wp-admin/includes/image.php: wp_generate_attachment_metadata()

Generate attachment meta data and create image sub-sizes for images.
wp-admin/includes/media.php: media_upload_form_handler()

Handles form submissions for the legacy media uploader.
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.
wp-admin/includes/ajax-actions.php: wp_ajax_upload_attachment()

Ajax handler for uploading attachments
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/class-custom-image-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/includes/class-custom-image-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/class-custom-image-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/includes/class-custom-background.php: Custom_Background::wp_set_background_image()
wp-admin/includes/class-custom-background.php: Custom_Background::handle_upload()

Handle an Image upload for the background image.
wp-includes/class-wp-embed.php: WP_Embed::shortcode()

The do_shortcode() callback function.
wp-includes/post.php: set_post_thumbnail()

Sets the post thumbnail (featured image) for the given post.
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-includes/nav-menu.php: wp_update_nav_menu_item()

Save the properties of a menu item or create a new one.
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User Contributed Notes User Contributed Notes

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    Contributed by Drew Jaynes —

    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.

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    Contributed by Codex —

    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:

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

//Or

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 );
?>

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    Edit Page template

    [/php]

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

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