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update_post_meta()

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

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Updates a post meta field based on the given 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 and its ID returned.

Can be used in place of add_post_meta() .

Parameters

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

Default:''

Return

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\""}

<?php $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""} */ ?>

Workaround

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

<?php $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\""} */ ?>

Source

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 ); }

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UsesDescription
wp_is_post_revision()wp-includes/revision.php

Determines if the specified post is a revision.

update_metadata()wp-includes/meta.php

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

Used byDescription
WP_REST_Attachments_Controller::edit_media_item()wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

Applies edits to a media item and creates a new attachment record.

_wp_privacy_account_request_confirmed()wp-includes/user.php

Updates log when privacy request is confirmed.

_wp_privacy_send_request_confirmation_notification()wp-includes/user.php

Notifies the site administrator via email when a request is confirmed.

_wp_privacy_send_erasure_fulfillment_notification()wp-includes/user.php

Notifies the user when their erasure request is fulfilled.

wp_privacy_process_personal_data_export_page()wp-admin/includes/privacy-tools.php

Intercept personal data exporter page Ajax responses in order to assemble the personal data export file.

wp_privacy_generate_personal_data_export_file()wp-admin/includes/privacy-tools.php

Generate the personal data export file.

_wp_privacy_completed_request()wp-admin/includes/privacy-tools.php

Marks a request as completed by the admin and logs the current timestamp.

WP_Customize_Manager::set_changeset_lock()wp-includes/class-wp-customize-manager.php

Marks the changeset post as being currently edited by the current user.

WP_Customize_Manager::refresh_changeset_lock()wp-includes/class-wp-customize-manager.php

Refreshes changeset lock with the current time if current user edited the changeset before.

WP_Customize_Manager::dismiss_user_auto_draft_changesets()wp-includes/class-wp-customize-manager.php

Dismisses all of the current user’s auto-drafts (other than the present one).

WP_Customize_Manager::import_theme_starter_content()wp-includes/class-wp-customize-manager.php

Imports theme starter content into the customized state.

WP_REST_Attachments_Controller::create_item()wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php

Creates a single attachment.

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

Updates a single attachment.

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

Sets the template for a post.

Custom_Background::ajax_background_add()wp-admin/includes/class-custom-background.php

Handles Ajax request for adding custom background context to an attachment.

wp_restore_image()wp-admin/includes/image-edit.php

Restores the metadata for a given attachment.

wp_save_image()wp-admin/includes/image-edit.php

Saves image to post, along with enqueued changes in $_REQUEST['history'].

wp_generate_attachment_metadata()wp-admin/includes/image.php

Generates attachment meta data and create image sub-sizes for images.

media_upload_form_handler()wp-admin/includes/media.php

Handles form submissions for the legacy media uploader.

wp_set_post_lock()wp-admin/includes/post.php

Marks the post as currently being edited by the current user.

edit_post()wp-admin/includes/post.php

Updates an existing post with values provided in $_POST.

bulk_edit_posts()wp-admin/includes/post.php

Processes the post data for the bulk editing of posts.

wp_ajax_upload_attachment()wp-admin/includes/ajax-actions.php

Handles uploading attachments via AJAX.

wp_ajax_wp_remove_post_lock()wp-admin/includes/ajax-actions.php

Handles removing a post lock via AJAX.

wp_ajax_save_attachment()wp-admin/includes/ajax-actions.php

Handles updating attachment attributes via AJAX.

Custom_Image_Header::ajax_header_add()wp-admin/includes/class-custom-image-header.php

Given an attachment ID for a header image, updates its “last used” timestamp to now.

Custom_Image_Header::customize_set_last_used()wp-admin/includes/class-custom-image-header.php

Updates the last-used postmeta on a header image attachment after saving a new header image via the Customizer.

Custom_Image_Header::set_header_image()wp-admin/includes/class-custom-image-header.php

Chooses a header image, selected from existing uploaded and default headers, or provides an array of uploaded header data (either new, or from media library).

Custom_Background::wp_set_background_image()wp-admin/includes/class-custom-background.php
Custom_Background::handle_upload()wp-admin/includes/class-custom-background.php

Handles an Image upload for the background image.

WP_Embed::shortcode()wp-includes/class-wp-embed.php

The do_shortcode() callback function.

set_post_thumbnail()wp-includes/post.php

Sets the post thumbnail (featured image) for the given post.

wp_update_attachment_metadata()wp-includes/post.php

Updates metadata for an attachment.

wp_insert_post()wp-includes/post.php

Inserts or update a post.

update_attached_file()wp-includes/post.php

Updates attachment file path based on attachment ID.

wp_restore_post_revision()wp-includes/revision.php

Restores a post to the specified revision.

wp_update_nav_menu_item()wp-includes/nav-menu.php

Saves the properties of a menu item or create a new one.

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Changelog

VersionDescription
1.5.0Introduced.

User Contributed Notes

  4. Skip to note 11 content
    elmachoiq
    You must log in to vote on the helpfulness of this noteVote results for this note: 1You must log in to vote on the helpfulness of this note

    ¡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",) $ticket_meta[0][0]["option_rsv_t"] = "9"; update_post_meta($azgTorneoID,"mep_event_ticket_type",$ticket_meta[0]);
  5. Skip to note 12 content
    Codex
    You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note

    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 ); ?>

    Edit Page template

    [/php]

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

  6. Skip to note 13 content
    Drew Jaynes
    You must log in to vote on the helpfulness of this noteVote results for this note: -1You must log in to vote on the helpfulness of this note

    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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