* WordPress Administration Revisions API
* @subpackage Administration
* Get the revision UI diff.
* @param WP_Post|int $post The post object or post ID.
* @param int $compare_from The revision ID to compare from.
* @param int $compare_to The revision ID to come to.
* @return array|false Associative array of a post's revisioned fields and their diffs.
function wp_get_revision_ui_diff( $post, $compare_from, $compare_to ) {
$post = get_post( $post );
$compare_from = get_post( $compare_from );
// If we're dealing with the first revision...
$compare_to = get_post( $compare_to );
// If comparing revisions, make sure we're dealing with the right post parent.
// The parent post may be a 'revision' when revisions are disabled and we're looking at autosaves.
if ( $compare_from && $compare_from->post_parent !== $post->ID && $compare_from->ID !== $post->ID ) {
if ( $compare_to->post_parent !== $post->ID && $compare_to->ID !== $post->ID ) {
if ( $compare_from && strtotime( $compare_from->post_date_gmt ) > strtotime( $compare_to->post_date_gmt ) ) {
$compare_from = $compare_to;
// Add default title if title field is empty.
if ( $compare_from && empty( $compare_from->post_title ) ) {
$compare_from->post_title = __( '(no title)' );
if ( empty( $compare_to->post_title ) ) {
$compare_to->post_title = __( '(no title)' );
foreach ( _wp_post_revision_fields( $post ) as $field => $name ) {
* Contextually filter a post revision field.
* The dynamic portion of the hook name, `$field`, corresponds to each of the post
* fields of the revision object being iterated over in a foreach statement.
* @param string $revision_field The current revision field to compare to or from.
* @param string $field The current revision field.
* @param WP_Post $compare_from The revision post object to compare to or from.
* @param string $context The context of whether the current revision is the old
* or the new one. Values are 'to' or 'from'.
$content_from = $compare_from ? apply_filters( "_wp_post_revision_field_{$field}", $compare_from->$field, $field, $compare_from, 'from' ) : '';
/** This filter is documented in wp-admin/includes/revision.php */
$content_to = apply_filters( "_wp_post_revision_field_{$field}", $compare_to->$field, $field, $compare_to, 'to' );
'show_split_view' => true,
'title_left' => __( 'Removed' ),
'title_right' => __( 'Added' ),
* Filters revisions text diff options.
* Filters the options passed to wp_text_diff() when viewing a post revision.
* Associative array of options to pass to wp_text_diff().
* @type bool $show_split_view True for split view (two columns), false for
* un-split view (single column). Default true.
* @param string $field The current revision field.
* @param WP_Post $compare_from The revision post to compare from.
* @param WP_Post $compare_to The revision post to compare to.
$args = apply_filters( 'revision_text_diff_options', $args, $field, $compare_from, $compare_to );
$diff = wp_text_diff( $content_from, $content_to, $args );
if ( ! $diff && 'post_title' === $field ) {
// It's a better user experience to still show the Title, even if it didn't change.
// No, you didn't see this.
$diff = '<table class="diff"><colgroup><col class="content diffsplit left"><col class="content diffsplit middle"><col class="content diffsplit right"></colgroup><tbody><tr>';
// In split screen mode, show the title before/after side by side.
if ( true === $args['show_split_view'] ) {
$diff .= '<td>' . esc_html( $compare_from->post_title ) . '</td><td></td><td>' . esc_html( $compare_to->post_title ) . '</td>';
$diff .= '<td>' . esc_html( $compare_from->post_title ) . '</td>';
// In single column mode, only show the title once if unchanged.
if ( $compare_from->post_title !== $compare_to->post_title ) {
$diff .= '</tr><tr><td>' . esc_html( $compare_to->post_title ) . '</td>';
$diff .= '</tr></tbody>';
* Filters the fields displayed in the post revision diff UI.
* @param array[] $return Array of revision UI fields. Each item is an array of id, name, and diff.
* @param WP_Post $compare_from The revision post to compare from.
* @param WP_Post $compare_to The revision post to compare to.
return apply_filters( 'wp_get_revision_ui_diff', $return, $compare_from, $compare_to );
* Prepare revisions for JavaScript.
* @param WP_Post|int $post The post object or post ID.
* @param int $selected_revision_id The selected revision ID.
* @param int $from Optional. The revision ID to compare from.
* @return array An associative array of revision data and related settings.
function wp_prepare_revisions_for_js( $post, $selected_revision_id, $from = null ) {
$post = get_post( $post );
$revisions = wp_get_post_revisions(
'check_enabled' => false,
// If revisions are disabled, we only want autosaves and the current post.
if ( ! wp_revisions_enabled( $post ) ) {
foreach ( $revisions as $revision_id => $revision ) {
if ( ! wp_is_post_autosave( $revision ) ) {
unset( $revisions[ $revision_id ] );
$revisions = array( $post->ID => $post ) + $revisions;
$show_avatars = get_option( 'show_avatars' );
cache_users( wp_list_pluck( $revisions, 'post_author' ) );
$can_restore = current_user_can( 'edit_post', $post->ID );
foreach ( $revisions as $revision ) {
$modified = strtotime( $revision->post_modified );
$modified_gmt = strtotime( $revision->post_modified_gmt . ' +0000' );
$restore_link = str_replace(
'revision' => $revision->ID,
admin_url( 'revision.php' )
"restore-post_{$revision->ID}"
if ( ! isset( $authors[ $revision->post_author ] ) ) {
$authors[ $revision->post_author ] = array(
'id' => (int) $revision->post_author,
'avatar' => $show_avatars ? get_avatar( $revision->post_author, 32 ) : '',
'name' => get_the_author_meta( 'display_name', $revision->post_author ),
$autosave = (bool) wp_is_post_autosave( $revision );
$current = ! $autosave && $revision->post_modified_gmt === $post->post_modified_gmt;
if ( $current && ! empty( $current_id ) ) {
// If multiple revisions have the same post_modified_gmt, highest ID is current.
if ( $current_id < $revision->ID ) {
$revisions[ $current_id ]['current'] = false;
$current_id = $revision->ID;
$current_id = $revision->ID;
'title' => get_the_title( $post->ID ),
'author' => $authors[ $revision->post_author ],
'date' => date_i18n( __( 'M j, Y @ H:i' ), $modified ),
'dateShort' => date_i18n( _x( 'j M @ H:i', 'revision date short format' ), $modified ),
/* translators: %s: Human-readable time difference. */
'timeAgo' => sprintf( __( '%s ago' ), human_time_diff( $modified_gmt, $now_gmt ) ),
'restoreUrl' => $can_restore ? $restore_link : false,
* Filters the array of revisions used on the revisions screen.
* @param array $revisions_data {
* The bootstrapped data for the revisions screen.
* @type int $id Revision ID.
* @type string $title Title for the revision's parent WP_Post object.
* @type int $author Revision post author ID.
* @type string $date Date the revision was modified.
* @type string $dateShort Short-form version of the date the revision was modified.
* @type string $timeAgo GMT-aware amount of time ago the revision was modified.
* @type bool $autosave Whether the revision is an autosave.
* @type bool $current Whether the revision is both not an autosave and the post
* modified date matches the revision modified date (GMT-aware).
* @type bool|false $restoreUrl URL if the revision can be restored, false otherwise.
* @param WP_Post $revision The revision's WP_Post object.
* @param WP_Post $post The revision's parent WP_Post object.
$revisions[ $revision->ID ] = apply_filters( 'wp_prepare_revision_for_js', $revisions_data, $revision, $post );
* If we only have one revision, the initial revision is missing; This happens
* when we have an autsosave and the user has clicked 'View the Autosave'
if ( 1 === count( $revisions ) ) {
$revisions[ $post->ID ] = array(
'title' => get_the_title( $post->ID ),
'author' => $authors[ $revision->post_author ],
'date' => date_i18n( __( 'M j, Y @ H:i' ), strtotime( $post->post_modified ) ),
'dateShort' => date_i18n( _x( 'j M @ H:i', 'revision date short format' ), strtotime( $post->post_modified ) ),
/* translators: %s: Human-readable time difference. */
'timeAgo' => sprintf( __( '%s ago' ), human_time_diff( strtotime( $post->post_modified_gmt ), $now_gmt ) ),
* If a post has been saved since the last revision (no revisioned fields
* were changed), we may not have a "current" revision. Mark the latest
if ( empty( $current_id ) ) {
if ( $revisions[ $revision->ID ]['autosave'] ) {
$revision = end( $revisions );
while ( $revision['autosave'] ) {
$revision = prev( $revisions );
$current_id = $revision['id'];
$current_id = $revision->ID;
$revisions[ $current_id ]['current'] = true;
// Now, grab the initial diff.
$compare_two_mode = is_numeric( $from );
if ( ! $compare_two_mode ) {
$found = array_search( $selected_revision_id, array_keys( $revisions ), true );
$from = array_keys( array_slice( $revisions, $found - 1, 1, true ) );
'id' => $from . ':' . $selected_revision_id,
'fields' => wp_get_revision_ui_diff( $post->ID, $from, $selected_revision_id ),
'nonce' => wp_create_nonce( 'revisions-ajax-nonce' ),
'revisionData' => array_values( $revisions ),
'to' => $selected_revision_id,
'baseUrl' => parse_url( admin_url( 'revision.php' ), PHP_URL_PATH ),
'compareTwoMode' => absint( $compare_two_mode ), // Apparently booleans are not allowed.
'revisionIds' => array_keys( $revisions ),
* Print JavaScript templates required for the revisions experience.
* @global WP_Post $post Global post object.
function wp_print_revision_templates() {
?><script id="tmpl-revisions-frame" type="text/html">
<div class="revisions-control-frame"></div>
<div class="revisions-diff-frame"></div>
<script id="tmpl-revisions-buttons" type="text/html">
<div class="revisions-previous">
<input class="button" type="button" value="<?php echo esc_attr_x( 'Previous', 'Button label for a previous revision' ); ?>" />
<div class="revisions-next">
<input class="button" type="button" value="<?php echo esc_attr_x( 'Next', 'Button label for a next revision' ); ?>" />
<script id="tmpl-revisions-checkbox" type="text/html">
<div class="revision-toggle-compare-mode">
<input type="checkbox" class="compare-two-revisions"
if ( 'undefined' !== typeof data && data.model.attributes.compareTwoMode ) {
<?php esc_html_e( 'Compare any two revisions' ); ?>
<script id="tmpl-revisions-meta" type="text/html">
<# if ( ! _.isUndefined( data.attributes ) ) { #>
<# if ( 'from' === data.type ) { #>
<strong><?php _ex( 'From:', 'Followed by post revision info' ); ?></strong>
<# } else if ( 'to' === data.type ) { #>
<strong><?php _ex( 'To:', 'Followed by post revision info' ); ?></strong>
<div class="author-card<# if ( data.attributes.autosave ) { #> autosave<# } #>">
{{{ data.attributes.author.avatar }}}
<div class="author-info">
<# if ( data.attributes.autosave ) { #>
/* translators: %s: User's display name. */
'<span class="author-name">{{ data.attributes.author.name }}</span>'
<# } else if ( data.attributes.current ) { #>
/* translators: %s: User's display name. */
__( 'Current Revision by %s' ),
'<span class="author-name">{{ data.attributes.author.name }}</span>'
/* translators: %s: User's display name. */
'<span class="author-name">{{ data.attributes.author.name }}</span>'
<span class="time-ago">{{ data.attributes.timeAgo }}</span>
<span class="date">({{ data.attributes.dateShort }})</span>
<# if ( 'to' === data.type && data.attributes.restoreUrl ) { #>
<input <?php if ( wp_check_post_lock( $post->ID ) ) { ?>
<# if ( data.attributes.current ) { #>
<# if ( data.attributes.autosave ) { #>
type="button" class="restore-revision button button-primary" value="<?php esc_attr_e( 'Restore This Autosave' ); ?>" />
type="button" class="restore-revision button button-primary" value="<?php esc_attr_e( 'Restore This Revision' ); ?>" />
<# if ( 'tooltip' === data.type ) { #>
<div class="revisions-tooltip-arrow"><span></span></div>
<script id="tmpl-revisions-diff" type="text/html">
<div class="loading-indicator"><span class="spinner"></span></div>
<div class="diff-error"><?php _e( 'Sorry, something went wrong. The requested comparison could not be loaded.' ); ?></div>
<# _.each( data.fields, function( field ) { #>
<h3>{{ field.name }}</h3>