Add missing doc blocks to post.php.

Clarify some existing values for `@param` and `@return`.
Some functions do not need to set a variable before immediately returning it.

See #32444.

Built from https://develop.svn.wordpress.org/trunk@32619


git-svn-id: http://core.svn.wordpress.org/trunk@32589 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Scott Taylor 2015-05-27 17:05:26 +00:00
parent 2f75a74b3e
commit 2ebce023df
2 changed files with 94 additions and 74 deletions

View File

@ -181,7 +181,7 @@ function create_initial_post_types() {
*
* @param int $attachment_id Attachment ID.
* @param bool $unfiltered Optional. Whether to apply filters. Default false.
* @return string|bool The file path to where the attached file should be, false otherwise.
* @return string|false The file path to where the attached file should be, false otherwise.
*/
function get_attached_file( $attachment_id, $unfiltered = false ) {
$file = get_post_meta( $attachment_id, '_wp_attached_file', true );
@ -308,6 +308,8 @@ function _wp_relative_upload_path( $path ) {
* @see get_posts()
* @todo Check validity of description.
*
* @global WP_Post $post
*
* @param mixed $args Optional. User defined arguments for replacing the defaults. Default empty.
* @param string $output Optional. Constant for return type. Accepts OBJECT, ARRAY_A, ARRAY_N.
* Default OBJECt.
@ -410,11 +412,13 @@ function get_extended( $post ) {
*
* @since 1.5.1
*
* @param int|WP_Post $post Optional. Post ID or post object. Defaults to global $post.
* @param string $output Optional, default is Object. Accepts OBJECT, ARRAY_A, or ARRAY_N.
* Default OBJECT.
* @param string $filter Optional. Type of filter to apply. Accepts 'raw', 'edit', 'db',
* or 'display'. Default 'raw'.
* @global WP_Post $post
*
* @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
* @param string $output Optional, default is Object. Accepts OBJECT, ARRAY_A, or ARRAY_N.
* Default OBJECT.
* @param string $filter Optional. Type of filter to apply. Accepts 'raw', 'edit', 'db',
* or 'display'. Default 'raw'.
* @return WP_Post|array|null Type corresponding to $output on success or null on failure.
* When $output is OBJECT, a `WP_Post` instance is returned.
*/
@ -644,8 +648,10 @@ final class WP_Post {
* @static
* @access public
*
* @global wpdb $wpdb
*
* @param int $post_id Post ID.
* @return WP_Post|bool Post object, false otherwise.
* @return WP_Post|false Post object, false otherwise.
*/
public static function get_instance( $post_id ) {
global $wpdb;
@ -707,7 +713,7 @@ final class WP_Post {
* Getter.
*
* @param string $key Key to get.
* @return array|mixed
* @return mixed
*/
public function __get( $key ) {
if ( 'page_template' == $key && $this->__isset( $key ) ) {
@ -750,7 +756,7 @@ final class WP_Post {
* {@Missing Summary}
*
* @param string $filter Filter.
* @return $this|array|bool|object|WP_Post
* @return self|array|bool|object|WP_Post
*/
public function filter( $filter ) {
if ( $this->filter == $filter )
@ -950,7 +956,7 @@ function get_page_statuses() {
* Arguments prefixed with an _underscore shouldn't be used by plugins and themes.
*
* @since 3.0.0
* @uses $wp_post_statuses Inserts new post status object into the list
* @global array $wp_post_statuses Inserts new post status object into the list
*
* @param string $post_status Name of the post status.
* @param array|string $args {
@ -981,6 +987,7 @@ function get_page_statuses() {
* e.g. All (12) | Published (9) | My Custom Status (2)
* Default is value of $internal.
* }
* @return object
*/
function register_post_status( $post_status, $args = array() ) {
global $wp_post_statuses;
@ -1057,7 +1064,7 @@ function register_post_status( $post_status, $args = array() ) {
* @see register_post_status()
*
* @param string $post_status The name of a registered post status.
* @return object A post status object.
* @return object|null A post status object.
*/
function get_post_status_object( $post_status ) {
global $wp_post_statuses;
@ -1132,8 +1139,8 @@ function post_type_exists( $post_type ) {
*
* @since 2.1.0
*
* @param int|WP_Post $post Optional. Post ID or post object. Default is global $post.
* @return string|false Post type on success, false on failure.
* @param int|WP_Post|null $post Optional. Post ID or post object. Default is global $post.
* @return string|false Post type on success, false on failure.
*/
function get_post_type( $post = null ) {
if ( $post = get_post( $post ) )
@ -1152,7 +1159,7 @@ function get_post_type( $post = null ) {
* @see register_post_type()
*
* @param string $post_type The name of a registered post type.
* @return object A post type object.
* @return object|null A post type object.
*/
function get_post_type_object( $post_type ) {
global $wp_post_types;
@ -1581,7 +1588,9 @@ function get_post_type_capabilities( $args ) {
* @since 3.1.0
* @access private
*
* @param null|array $capabilities Post type meta capabilities.
* @staticvar array $meta_caps
*
* @param array|void $capabilities Post type meta capabilities.
*/
function _post_type_meta_capabilities( $capabilities = null ) {
static $meta_caps = array();
@ -1695,7 +1704,7 @@ function _get_custom_object_labels( $object, $nohier_vs_hier_defaults ) {
$defaults[$key] = $object->hierarchical ? $value[1] : $value[0];
}
$labels = array_merge( $defaults, $object->labels );
return (object)$labels;
return (object) $labels;
}
/**
@ -1728,6 +1737,8 @@ function _add_post_type_submenus() {
*
* @since 3.0.0
*
* @global array $_wp_post_type_features
*
* @param string $post_type The post type for which to add the feature.
* @param string|array $feature The feature being added, accepts an array of
* feature strings or a single string.
@ -1749,6 +1760,8 @@ function add_post_type_support( $post_type, $feature ) {
*
* @since 3.0.0
*
* @global array $_wp_post_type_features
*
* @param string $post_type The post type for which to remove the feature.
* @param string $feature The feature being removed.
*/
@ -1763,6 +1776,8 @@ function remove_post_type_support( $post_type, $feature ) {
*
* @since 3.4.0
*
* @global array $_wp_post_type_features
*
* @param string $post_type The post type.
* @return array Post type supports list.
*/
@ -1780,8 +1795,10 @@ function get_all_post_type_supports( $post_type ) {
*
* @since 3.0.0
*
* @global array $_wp_post_type_features
*
* @param string $post_type The post type being checked.
* @param string $feature the feature being checked.
* @param string $feature The feature being checked.
* @return bool Whether the post type supports the given feature.
*/
function post_type_supports( $post_type, $feature ) {
@ -1802,7 +1819,7 @@ function post_type_supports( $post_type, $feature ) {
* @param int $post_id Optional. Post ID to change post type. Default 0.
* @param string $post_type Optional. Post type. Accepts 'post' or 'page' to
* name a few. Default 'post'.
* @return int Amount of rows changed. Should be 1 for success and 0 for failure.
* @return int|false Amount of rows changed. Should be 1 for success and 0 for failure.
*/
function set_post_type( $post_id = 0, $post_type = 'post' ) {
global $wpdb;
@ -1892,7 +1909,7 @@ function get_posts( $args = null ) {
* @param mixed $meta_value Metadata value. Must be serializable if non-scalar.
* @param bool $unique Optional. Whether the same key should not be added.
* Default false.
* @return int|bool Meta ID on success, false on failure.
* @return int|false Meta ID on success, false on failure.
*/
function add_post_meta( $post_id, $meta_key, $meta_value, $unique = false ) {
// Make sure meta is added to the post, not a revision.
@ -2006,8 +2023,7 @@ function get_post_custom( $post_id = 0 ) {
* @since 1.2.0
*
* @param int $post_id Optional. Post ID. Default is ID of the global $post.
* @return array|null Either array of the keys, or null if keys could not be
* retrieved.
* @return array|void Array of the keys, if retrieved.
*/
function get_post_custom_keys( $post_id = 0 ) {
$custom = get_post_custom( $post_id );
@ -2029,7 +2045,7 @@ function get_post_custom_keys( $post_id = 0 ) {
*
* @param string $key Optional. Meta field key. Default empty.
* @param int $post_id Optional. Post ID. Default is ID of the global $post.
* @return array Meta field values.
* @return array|null Meta field values.
*/
function get_post_custom_values( $key = '', $post_id = 0 ) {
if ( !$key )
@ -2342,6 +2358,8 @@ function _count_posts_cache_key( $type = 'post', $perm = '' ) {
*
* @since 2.5.0
*
* @global wpdb $wpdb
*
* @param string $type Optional. Post type to retrieve count. Default 'post'.
* @param string $perm Optional. 'readable' or empty. Default empty.
* @return object Number of posts for each status.
@ -2405,6 +2423,8 @@ function wp_count_posts( $type = 'post', $perm = '' ) {
*
* @since 2.5.0
*
* @global wpdb $wpdb
*
* @param string|array $mime_type Optional. Array or comma-separated list of
* MIME patterns. Default empty.
* @return object An object containing the attachment counts by mime type.
@ -2579,7 +2599,7 @@ function wp_post_mime_type_where( $post_mime_types, $table_alias = '' ) {
* @param int $postid Optional. Post ID. Default 0.
* @param bool $force_delete Optional. Whether to bypass trash and force deletion.
* Default false.
* @return array|bool|WP_Post False on failure.
* @return array|false|WP_Post False on failure.
*/
function wp_delete_post( $postid = 0, $force_delete = false ) {
global $wpdb;
@ -2722,7 +2742,7 @@ function _reset_front_page_settings_for_post( $post_id ) {
*
* @param int $post_id Optional. Post ID. Default is ID of the global $post
* if EMPTY_TRASH_DAYS equals true.
* @return bool|array Post data array, otherwise false.
* @return false|array|WP_Post|null Post data array, otherwise false.
*/
function wp_trash_post( $post_id = 0 ) {
if ( !EMPTY_TRASH_DAYS )
@ -2769,7 +2789,7 @@ function wp_trash_post( $post_id = 0 ) {
* @since 2.9.0
*
* @param int $post_id Optional. Post ID. Default is ID of the global $post.
* @return WP_Post|bool WP_Post object. False on failure.
* @return WP_Post|false WP_Post object. False on failure.
*/
function wp_untrash_post( $post_id = 0 ) {
if ( !$post = get_post($post_id, ARRAY_A) )
@ -2817,8 +2837,8 @@ function wp_untrash_post( $post_id = 0 ) {
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param int|WP_Post $post Optional. Post ID or post object. Defaults to global $post.
* @return mixed False on failure.
* @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
* @return mixed|void False on failure.
*/
function wp_trash_post_comments( $post = null ) {
global $wpdb;
@ -2871,8 +2891,10 @@ function wp_trash_post_comments( $post = null ) {
*
* @since 2.9.0
*
* @param int|WP_Post $post Optional. Post ID or post object. Defaults to global $post.
* @return null|bool Null on failure.
* @global wpdb $wpdb
*
* @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
* @return true|void
*/
function wp_untrash_post_comments( $post = null ) {
global $wpdb;
@ -3002,7 +3024,7 @@ function wp_get_post_terms( $post_id = 0, $taxonomy = 'post_tag', $args = array(
*
* @param array $args Optional. Arguments to retrieve posts. Default empty array.
* @param string $output Optional. Type of output. Accepts ARRAY_A or ''. Default ARRAY_A.
* @return array|bool Associative array if $output equals ARRAY_A, array or false if no results.
* @return array|false Associative array if $output equals ARRAY_A, array or false if no results.
*/
function wp_get_recent_posts( $args = array(), $output = ARRAY_A ) {
@ -3661,11 +3683,8 @@ function wp_publish_post( $post ) {
* @since 2.5.0
*
* @param int|WP_Post $post_id Post ID or post object.
* @return null Nothing is returned. Which can mean that no action is required
* or post was published.
*/
function check_and_publish_future_post( $post_id ) {
$post = get_post($post_id);
if ( empty($post) )
@ -3683,7 +3702,8 @@ function check_and_publish_future_post( $post_id ) {
return;
}
return wp_publish_post($post_id);
// wp_publish_post(_ returns no meaninful value
wp_publish_post( $post_id );
}
/**
@ -3691,7 +3711,7 @@ function check_and_publish_future_post( $post_id ) {
*
* @since 2.8.0
*
* @global wpdb $wpdb WordPress database abstraction object.
* @global wpdb $wpdb WordPress database abstraction object.
* @global WP_Rewrite $wp_rewrite
*
* @param string $slug The desired slug (post_name).
@ -3839,7 +3859,7 @@ function _truncate_post_slug( $slug, $length = 200 ) {
* @param int $post_id Optional. The Post ID. Does not default to the ID of the global $post.
* Default 0.
* @param string $tags Optional. The tags to set for the post, separated by commas. Default empty.
* @return bool|null Will return false if $post_id is not an integer or is 0. Will return null otherwise.
* @return array|false|WP_Error Will return false if $post_id is not an integer or is 0.
*/
function wp_add_post_tags( $post_id = 0, $tags = '' ) {
return wp_set_post_tags($post_id, $tags, true);
@ -3857,7 +3877,7 @@ function wp_add_post_tags( $post_id = 0, $tags = '' ) {
* Default empty.
* @param bool $append Optional. If true, don't delete existing tags, just add on. If false,
* replace the tags with the new tags. Default false.
* @return mixed Array of affected term IDs. WP_Error or false on failure.
* @return array|false|WP_Error Array of affected term IDs. WP_Error or false on failure.
*/
function wp_set_post_tags( $post_id = 0, $tags = '', $append = false ) {
return wp_set_post_terms( $post_id, $tags, 'post_tag', $append);
@ -3875,7 +3895,7 @@ function wp_set_post_tags( $post_id = 0, $tags = '', $append = false ) {
* @param string $taxonomy Optional. Taxonomy name. Default 'post_tag'.
* @param bool $append Optional. If true, don't delete existing tags, just add on. If false,
* replace the tags with the new tags. Default false.
* @return mixed Array of affected term IDs. WP_Error or false on failure.
* @return array|false|WP_Error Array of affected term IDs. WP_Error or false on failure.
*/
function wp_set_post_terms( $post_id = 0, $tags = '', $taxonomy = 'post_tag', $append = false ) {
$post_id = (int) $post_id;
@ -3918,7 +3938,7 @@ function wp_set_post_terms( $post_id = 0, $tags = '', $taxonomy = 'post_tag', $a
* Default empty array.
* @param bool $append If true, don't delete existing categories, just add on.
* If false, replace the categories with the new categories.
* @return bool|mixed
* @return array|bool|WP_Error
*/
function wp_set_post_categories( $post_ID = 0, $post_categories = array(), $append = false ) {
$post_ID = (int) $post_ID;
@ -4017,7 +4037,7 @@ function wp_transition_post_status( $new_status, $old_status, $post ) {
*
* @param int $post_id Post ID.
* @param string $uri Ping URI.
* @return int How many rows were updated.
* @return int|false How many rows were updated.
*/
function add_ping( $post_id, $uri ) {
global $wpdb;
@ -4072,8 +4092,7 @@ function get_enclosed( $post_id ) {
* @param array $pung Array of enclosures for the given post.
* @param int $post_id Post ID.
*/
$pung = apply_filters( 'get_enclosed', $pung, $post_id );
return $pung;
return apply_filters( 'get_enclosed', $pung, $post_id );
}
/**
@ -4099,8 +4118,7 @@ function get_pung( $post_id ) {
*
* @param array $pung Array of URLs already pinged for the given post.
*/
$pung = apply_filters( 'get_pung', $pung );
return $pung;
return apply_filters( 'get_pung', $pung );
}
/**
@ -4126,8 +4144,7 @@ function get_to_ping( $post_id ) {
*
* @param array $to_ping List of URLs yet to ping.
*/
$to_ping = apply_filters( 'get_to_ping', $to_ping );
return $to_ping;
return apply_filters( 'get_to_ping', $to_ping );
}
/**
@ -4196,7 +4213,7 @@ function get_all_page_ids() {
* Default OBJECT.
* @param string $filter Optional. How the return value should be filtered. Accepts 'raw',
* 'edit', 'db', 'display'. Default 'raw'.
* @return WP_Post|null WP_Post on success or null on failure.
* @return WP_Post|array|null WP_Post on success or null on failure.
*/
function get_page( $page, $output = OBJECT, $filter = 'raw') {
return get_post( $page, $output, $filter );
@ -4213,7 +4230,7 @@ function get_page( $page, $output = OBJECT, $filter = 'raw') {
* @param string $output Optional. Output type. Accepts OBJECT, ARRAY_N, or ARRAY_A.
* Default OBJECT.
* @param string|array $post_type Optional. Post type or array of post types. Default 'page'.
* @return WP_Post|null WP_Post on success or null on failure.
* @return WP_Post|array|void WP_Post on success.
*/
function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
global $wpdb;
@ -4267,10 +4284,9 @@ function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
}
}
if ( $foundid )
if ( $foundid ) {
return get_post( $foundid, $output );
return null;
}
}
/**
@ -4284,7 +4300,7 @@ function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
* @param string $output Optional. Output type. OBJECT, ARRAY_N, or ARRAY_A.
* Default OBJECT.
* @param string|array $post_type Optional. Post type or array of post types. Default 'page'.
* @return WP_Post|null WP_Post on success or null on failure
* @return WP_Post|array|void WP_Post on success or null on failure
*/
function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' ) {
global $wpdb;
@ -4309,10 +4325,9 @@ function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' )
$page = $wpdb->get_var( $sql );
if ( $page )
if ( $page ) {
return get_post( $page, $output );
return null;
}
}
/**
@ -4369,8 +4384,7 @@ function get_page_children( $page_id, $pages ) {
*/
function get_page_hierarchy( &$pages, $page_id = 0 ) {
if ( empty( $pages ) ) {
$result = array();
return $result;
return array();
}
$children = array();
@ -4470,7 +4484,7 @@ function get_page_uri( $page ) {
* @type string $post_status A comma-separated list of post status types to include.
* Default 'publish'.
* }
* @return array List of pages matching defaults or `$args`.
* @return array|false List of pages matching defaults or `$args`.
*/
function get_pages( $args = array() ) {
global $wpdb;
@ -4722,9 +4736,7 @@ function get_pages( $args = array() ) {
* @param array $pages List of pages to retrieve.
* @param array $r Array of get_pages() arguments.
*/
$pages = apply_filters( 'get_pages', $pages, $r );
return $pages;
return apply_filters( 'get_pages', $pages, $r );
}
//
@ -4910,7 +4922,7 @@ function wp_delete_attachment( $post_id, $force_delete = false ) {
*
* @param int $post_id Attachment ID. Default 0.
* @param bool $unfiltered Optional. If true, filters are not run. Default false.
* @return string|bool Attachment meta field. False on failure.
* @return mixed Attachment meta field. False on failure.
*/
function wp_get_attachment_metadata( $post_id = 0, $unfiltered = false ) {
$post_id = (int) $post_id;
@ -4967,8 +4979,10 @@ function wp_update_attachment_metadata( $post_id, $data ) {
*
* @since 2.1.0
*
* @global string $pagenow
*
* @param int $post_id Optional. Attachment ID. Default 0.
* @return string|bool Attachment URL, otherwise false.
* @return string|false Attachment URL, otherwise false.
*/
function wp_get_attachment_url( $post_id = 0 ) {
$post_id = (int) $post_id;
@ -5031,7 +5045,7 @@ function wp_get_attachment_url( $post_id = 0 ) {
* @since 2.1.0
*
* @param int $post_id Optional. Attachment ID. Default 0.
* @return mixed False on failure. Thumbnail file path on success.
* @return string|false False on failure. Thumbnail file path on success.
*/
function wp_get_attachment_thumb_file( $post_id = 0 ) {
$post_id = (int) $post_id;
@ -5062,7 +5076,7 @@ function wp_get_attachment_thumb_file( $post_id = 0 ) {
* @since 2.1.0
*
* @param int $post_id Optional. Attachment ID. Default 0.
* @return string|bool False on failure. Thumbnail URL on success.
* @return string|false False on failure. Thumbnail URL on success.
*/
function wp_get_attachment_thumb_url( $post_id = 0 ) {
$post_id = (int) $post_id;
@ -5160,7 +5174,7 @@ function wp_attachment_is_image( $post = 0 ) {
* @since 2.1.0
*
* @param string|int $mime MIME type or attachment ID.
* @return string|bool Icon, false otherwise.
* @return string|false Icon, false otherwise.
*/
function wp_mime_type_icon( $mime = 0 ) {
if ( !is_numeric($mime) )
@ -5294,7 +5308,6 @@ function wp_mime_type_icon( $mime = 0 ) {
* @param int $post_id Post ID.
* @param WP_Post $post The Post Object
* @param WP_Post $post_before The Previous Post Object
* @return int Same as $post_id
*/
function wp_check_for_changed_slugs( $post_id, $post, $post_before ) {
// Don't bother if it hasnt changed.
@ -5342,6 +5355,8 @@ function get_private_posts_cap_sql( $post_type ) {
*
* @see get_private_posts_cap_sql()
*
* @global wpdb $wpdb
*
* @param array|string $post_type Single post type or an array of post types.
* @param bool $full Optional. Returns a full WHERE statement instead of just
* an 'andalso' term. Default true.
@ -5483,10 +5498,12 @@ function get_lastpostmodified( $timezone = 'server' ) {
* @since 3.1.0
* @access private
*
* @global wpdb $wpdb
*
* @param string $timezone The timezone for the timestamp. See {@see get_lastpostmodified()}
* for information on accepted values.
* @param string $field Post field to check. Accepts 'date' or 'modified'.
* @return string The timestamp.
* @return string|false The timestamp.
*/
function _get_last_post_time( $timezone, $field ) {
global $wpdb;
@ -5552,6 +5569,7 @@ function update_post_cache( &$posts ) {
*
* @since 2.0.0
*
* @global bool $_wp_suspend_cache_invalidation
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param int|WP_Post $post Post ID or post object to remove from the cache.
@ -5655,8 +5673,8 @@ function update_post_caches( &$posts, $post_type = 'post', $update_term_cache =
* @since 2.1.0
*
* @param array $post_ids List of post IDs.
* @return bool|array Returns false if there is nothing to update or an array
* of metadata.
* @return array|false Returns false if there is nothing to update or an array
* of metadata.
*/
function update_postmeta_cache( $post_ids ) {
return update_meta_cache('post', $post_ids);
@ -5672,7 +5690,7 @@ function update_postmeta_cache( $post_ids ) {
*
* @since 3.0.0
*
* @see wp_suspend_cache_invalidation()
* @global bool $_wp_suspend_cache_invalidation
*
* @param int $id The attachment ID in the cache to clean.
* @param bool $clean_terms Optional. Whether to clean terms cache. Default false.
@ -5812,7 +5830,7 @@ function _publish_post_hook( $post_id ) {
*
* @param int $post_ID
*
* @return int|bool Post parent ID, otherwise false.
* @return int|false Post parent ID, otherwise false.
*/
function wp_get_post_parent_id( $post_ID ) {
$post = get_post( $post_ID );
@ -5870,7 +5888,7 @@ function wp_check_post_hierarchy_for_loops( $post_parent, $post_ID ) {
*
* @param int|WP_Post $post Post ID or post object where thumbnail should be attached.
* @param int $thumbnail_id Thumbnail to attach.
* @return bool True on success, false on failure.
* @return int|bool True on success, false on failure.
*/
function set_post_thumbnail( $post, $thumbnail_id ) {
$post = get_post( $post );
@ -5946,6 +5964,8 @@ function _update_term_count_on_transition_post_status( $new_status, $old_status,
*
* @see update_post_caches()
*
* @global wpdb $wpdb
*
* @param array $ids ID list
* @param bool $update_term_cache Optional. Whether to update the term cache. Default true.
* @param bool $update_meta_cache Optional. Whether to update the meta cache. Default true.

View File

@ -4,7 +4,7 @@
*
* @global string $wp_version
*/
$wp_version = '4.3-alpha-32618';
$wp_version = '4.3-alpha-32619';
/**
* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.