<?php
/**
* @package ACF
* @author WP Engine
*
* © 2025 Advanced Custom Fields (ACF®). All rights reserved.
* "ACF" is a trademark of WP Engine.
* Licensed under the GNU General Public License v2 or later.
* https://www.gnu.org/licenses/gpl-2.0.html
*/
if ( ! defined( 'ABSPATH' ) ) {
exit; // Exit if accessed directly
}
if ( ! class_exists( 'acf_revisions' ) ) :
class acf_revisions {
/**
* An array to cache post IDs for revisions.
* @var array
*/
public $cache = array();
/**
* Constructs the acf_revisions class.
*/
public function __construct() {
add_action( 'wp_restore_post_revision', array( $this, 'wp_restore_post_revision' ), 10, 2 );
add_filter( '_wp_post_revision_fields', array( $this, 'wp_preview_post_fields' ), 10, 2 );
add_filter( '_wp_post_revision_fields', array( $this, 'wp_post_revision_fields' ), 10, 2 );
add_filter( 'acf/validate_post_id', array( $this, 'acf_validate_post_id' ), 10, 2 );
// WP 6.4+ handles things differently.
if ( version_compare( get_bloginfo( 'version' ), '6.4', '>=' ) ) {
add_action( '_wp_put_post_revision', array( $this, 'maybe_save_revision' ), 10, 2 );
add_filter( 'wp_save_post_revision_post_has_changed', array( $this, 'check_acf_fields_have_changed' ), 9, 3 );
add_filter( 'wp_post_revision_meta_keys', array( $this, 'wp_post_revision_meta_keys' ) );
$this->register_meta();
} else {
add_filter( 'wp_save_post_revision_check_for_changes', array( $this, 'wp_save_post_revision_check_for_changes' ), 10, 3 );
}
}
/**
* Registers any ACF meta that should be sent the REST/Gutenberg request.
* For now, this is just our "_acf_changed" key that we use to detect if ACF fields have changed.
*
* @since 6.2.6
*/
public function register_meta() {
register_meta(
'post',
'_acf_changed',
array(
'type' => 'boolean',
'single' => true,
'show_in_rest' => true,
'revisions_enabled' => true,
'auth_callback' => '__return_true',
)
);
}
/**
* Lets WordPress know which meta keys to include in revisions.
* For now, this is just our "_acf_changed" key, as we still handle revisions ourselves.
*
* @since 6.2.6
*
* @param array $keys The meta keys that should be revisioned.
* @return array
*/
public function wp_post_revision_meta_keys( $keys ) {
$keys[] = '_acf_changed';
return $keys;
}
/**
* Helps WordPress determine if fields have changed, and if in a legacy
* metabox AJAX request, copies the metadata to the new revision.
*
* @since 6.2.6
*
* @param boolean $post_has_changed True if the post has changed, false if not.
* @param WP_Post $last_revision The WP_Post object for the latest revision.
* @param WP_Post $post The WP_Post object for the parent post.
* @return boolean
*/
public function check_acf_fields_have_changed( $post_has_changed, $last_revision, $post ) {
if ( acf_maybe_get_GET( 'meta-box-loader', false ) ) {
// We're in a legacy AJAX request, so we copy fields over to the latest revision.
$this->maybe_save_revision( $last_revision->ID, $post->ID );
} elseif ( acf_maybe_get_POST( '_acf_changed', false ) ) {
// We're in a classic editor save request, so notify WP that fields have changed.
$post_has_changed = true;
}
// Let WordPress decide for REST/block editor requests.
return $post_has_changed;
}
/**
* Copies ACF field data to the latest revision.
*
* @since 6.2.6
*
* @param integer $revision_id The ID of the revision that was just created.
* @param integer $post_id The ID of the post being updated.
* @return void
*/
public function maybe_save_revision( $revision_id, $post_id ) {
// We don't have anything to copy over yet.
if ( ! did_action( 'acf/save_post' ) ) {
delete_metadata( 'post', $post_id, '_acf_changed' );
delete_metadata( 'post', $revision_id, '_acf_changed' );
return;
}
// Bail if this is an autosave in Classic Editor, it already has the field values.
if ( acf_maybe_get_POST( '_acf_changed' ) && wp_is_post_autosave( $revision_id ) ) {
return;
}
// Copy the saved meta from the main post to the latest revision.
acf_save_post_revision( $post_id );
}
/**
* This function is used to trick WP into thinking that one of the $post's fields has changed and
* will allow an autosave to be updated.
* Fixes an odd bug causing the preview page to render the non autosave post data on every odd attempt
*
* @type function
* @date 21/10/2014
* @since 5.1.0
*
* @param $fields (array)
* @return $fields
*/
function wp_preview_post_fields( $fields ) {
// bail early if not previewing a post
if ( acf_maybe_get_POST( 'wp-preview' ) !== 'dopreview' ) {
return $fields;
}
// add to fields if ACF has changed
if ( acf_maybe_get_POST( '_acf_changed' ) ) {
$fields['_acf_changed'] = 'different than 1';
}
// return
return $fields;
}
/**
* This filter will return false and force WP to save a revision. This is required due to
* WP checking only post_title, post_excerpt and post_content values, not custom fields.
*
* @type filter
* @date 19/09/13
*
* @param boolean $return defaults to true
* @param object $last_revision the last revision that WP will compare against
* @param object $post the $post object that WP will compare against
* @return boolean $return
*/
function wp_save_post_revision_check_for_changes( $return, $last_revision, $post ) {
// if acf has changed, return false and prevent WP from performing 'compare' logic
if ( acf_maybe_get_POST( '_acf_changed' ) ) {
return false;
}
// return
return $return;
}
/**
* This filter will add the ACF fields to the returned array
* Versions 3.5 and 3.6 of WP feature different uses of the revisions filters, so there are
* some hacks to allow both versions to work correctly
*
* @type filter
* @date 11/08/13
*
* @param $post_id (int)
* @return $post_id (int)
*/
function wp_post_revision_fields( $fields, $post = null ) {
// validate page
if ( acf_is_screen( 'revision' ) || acf_is_ajax( 'get-revision-diffs' ) ) {
// bail early if is restoring
if ( acf_maybe_get_GET( 'action' ) === 'restore' ) {
return $fields;
}
// allow
} else {
// bail early (most likely saving a post)
return $fields;
}
// vars
$append = array();
$order = array();
$post_id = acf_maybe_get( $post, 'ID' );
// compatibility with WP < 4.5 (test)
if ( ! $post_id ) {
global $post;
$post_id = $post->ID;
}
// get all postmeta
$meta = get_post_meta( $post_id );
// bail early if no meta
if ( ! $meta ) {
return $fields;
}
// loop
foreach ( $meta as $name => $value ) {
// attempt to find key value
$key = acf_maybe_get( $meta, '_' . $name );
// bail early if no key
if ( ! $key ) {
continue;
}
// update vars
$value = $value[0];
$key = $key[0];
// Load field.
$field = acf_get_field( $key );
if ( ! $field ) {
continue;
}
// get field
$field_title = $field['label'] . ' (' . $name . ')';
$field_order = $field['menu_order'];
$ancestors = acf_get_field_ancestors( $field );
// ancestors
if ( ! empty( $ancestors ) ) {
// vars
$count = count( $ancestors );
$oldest = acf_get_field( $ancestors[ $count - 1 ] );
// update vars
$field_title = str_repeat( '- ', $count ) . $field_title;
$field_order = $oldest['menu_order'] . '.1';
}
// append
$append[ $name ] = $field_title;
$order[ $name ] = $field_order;
// hook into specific revision field filter and return local value
add_filter( "_wp_post_revision_field_{$name}", array( $this, 'wp_post_revision_field' ), 10, 4 );
}
// append
if ( ! empty( $append ) ) {
// vars
$prefix = '_';
// add prefix
$append = acf_add_array_key_prefix( $append, $prefix );
$order = acf_add_array_key_prefix( $order, $prefix );
// sort by name (orders sub field values correctly)
array_multisort( $order, $append );
// remove prefix
$append = acf_remove_array_key_prefix( $append, $prefix );
// append
$fields = $fields + $append;
}
// return
return $fields;
}
/**
* Load the value for the given field and return it for rendering.
*
* @param mixed $value Should be false as it has not yet been loaded.
* @param string $field_name The name of the field
* @param mixed $post Holds the $post object to load from - in WP 3.5, this is not passed!
* @param string $direction To / from - not used.
* @return string $value
*/
public function wp_post_revision_field( $value, $field_name, $post = null, $direction = false ) {
// Bail early if is empty.
if ( empty( $value ) ) {
return '';
}
$value = acf_maybe_unserialize( $value );
$post_id = $post->ID;
// load field.
$field = acf_maybe_get_field( $field_name, $post_id );
// default formatting.
if ( is_array( $value ) ) {
$value = implode( ', ', $value );
} elseif ( is_object( $value ) ) {
$value = serialize( $value );
}
// image.
if ( is_array( $field ) && isset( $field['type'] ) && ( $field['type'] === 'image' || $field['type'] === 'file' ) ) {
$url = wp_get_attachment_url( $value );
$value = $value . ' (' . $url . ')';
}
return $value;
}
/**
* This action will copy and paste the metadata from a revision to the post
*
* @type action
* @date 11/08/13
*
* @param $parent_id (int) the destination post
* @return $revision_id (int) the source post
*/
function wp_restore_post_revision( $post_id, $revision_id ) {
// copy postmeta from revision to post (restore from revision)
acf_copy_postmeta( $revision_id, $post_id );
// Make sure the latest revision is also updated to match the new $post data
// get latest revision
$revision = acf_get_post_latest_revision( $post_id );
// save
if ( $revision ) {
// copy postmeta from revision to latest revision (potentialy may be the same, but most likely are different)
acf_copy_postmeta( $revision_id, $revision->ID );
}
}
/**
* This function will modify the $post_id and allow loading values from a revision
*
* @type function
* @date 6/3/17
* @since 5.5.10
*
* @param $post_id (int)
* @param $_post_id (int)
* @return $post_id (int)
*/
function acf_validate_post_id( $post_id, $_post_id ) {
// phpcs:disable WordPress.Security.NonceVerification.Recommended
// bail early if no preview in URL
if ( ! isset( $_GET['preview'] ) ) {
return $post_id;
}
// bail early if $post_id is not numeric
if ( ! is_numeric( $post_id ) ) {
return $post_id;
}
// vars
$k = $post_id;
$preview_id = 0;
// check cache
if ( isset( $this->cache[ $k ] ) ) {
return $this->cache[ $k ];
}
// validate
if ( isset( $_GET['preview_id'] ) ) {
$preview_id = (int) $_GET['preview_id'];
} elseif ( isset( $_GET['p'] ) ) {
$preview_id = (int) $_GET['p'];
} elseif ( isset( $_GET['page_id'] ) ) {
$preview_id = (int) $_GET['page_id'];
}
// phpcs:enable WordPress.Security.NonceVerification.Recommended
// bail early id $preview_id does not match $post_id
if ( $preview_id != $post_id ) {
return $post_id;
}
// attempt find revision
$revision = acf_get_post_latest_revision( $post_id );
// save
if ( $revision && $revision->post_parent == $post_id ) {
$post_id = (int) $revision->ID;
}
// set cache
$this->cache[ $k ] = $post_id;
// return
return $post_id;
}
}
// initialize
acf()->revisions = new acf_revisions();
endif; // class_exists check
/**
* This function will copy meta from a post to it's latest revision
*
* @type function
* @date 26/09/2016
* @since 5.4.0
*
* @param $post_id (int)
* @return n/a
*/
function acf_save_post_revision( $post_id = 0 ) {
// get latest revision
$revision = acf_get_post_latest_revision( $post_id );
// save
if ( $revision ) {
acf_copy_postmeta( $post_id, $revision->ID );
}
}
/**
* This function will return the latest revision for a given post
*
* @type function
* @date 25/06/2016
* @since 5.3.8
*
* @param $post_id (int)
* @return $post_id (int)
*/
function acf_get_post_latest_revision( $post_id ) {
// vars
$revisions = wp_get_post_revisions( $post_id );
// shift off and return first revision (will return null if no revisions)
$revision = array_shift( $revisions );
// return
return $revision;
}
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