[wp-trac] [WordPress Trac] #56025: wp_validate_boolean() not doing what it describes, causes issues with [video] shortcode

WordPress Trac noreply at wordpress.org
Tue Jun 21 08:51:00 UTC 2022

#56025: wp_validate_boolean() not doing what it describes, causes issues with
[video] shortcode
 Reporter:  arnodeleeuw   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Shortcodes    |    Version:  6.0
 Severity:  normal        |   Keywords:
  Focuses:                |
 == The function in question:

 * Filter/validate a variable as a boolean.
 * Alternative to `filter_var( $var, FILTER_VALIDATE_BOOLEAN )`.
 * @since 4.0.0
 * @param mixed $var Boolean value to validate.
 * @return bool Whether the value is validated.
 function wp_validate_boolean( $var ) {
     if ( is_bool( $var ) ) {
         return $var;

     if ( is_string( $var ) && 'false' === strtolower( $var ) ) {
         return false;

     return (bool) $var;

 == Steps to recreate the issue:
 Add the following shortcodes to a page:

 [video src="YOUR-SOURCE-HERE"]
 [video src="YOUR-SOURCE-HERE" loop="off"]
 [video src="YOUR-SOURCE-HERE" loop="0"]
 [video src="YOUR-SOURCE-HERE" loop="false"]

 - The first shortcode works as intended, rendering a video on the frontend
 without the loop attribute.
 - The second shortcode's <video> element will have the attribute
 {{{loop="1"}}} despite the loop attribute being set to off.
 - The third and fourth shortcode's <video> elements will **not** have the
 loop attribute set.

 == Description:
 wp_validate_boolean() says it 's an alternative to {{{ filter_var( $var,
 {{{filter_var( $var, FILTER_VALIDATE_BOOLEAN )}}} will return **FALSE**
 when you pass the string "off" whereas {{{wp_validate_boolean()}}} will
 return **TRUE** in this case.
 (See this for the documentation for filter_validate_boolean:

 Currently, {{{wp_validate_boolean()}}} only returns **FALSE** if the $var
 is a string and if it is === "false", or if the $var passed is the int 0.

 This causes unexpected behaviour in the [video] shortcode. The
 documentation of the video shortcode
 ([https://wordpress.org/support/article/video-shortcode/]) mentions that
 the loop attribute needs to be either "on"/"off". Because they are strings
 {{{wp_validate_boolean()}}} will return **TRUE**, causing the loop
 attribute to always be added with a value of "1" unless you change the
 value of the attribute to be specifically the string "false", the int 0,
 or leave it completely empty.

 The parsing of the attributes of the [video] shortcode happens here:
 As you can see on line 3340 it uses {{{wp_validate_boolean()}}} to get
 filter value of the loop attribute. Passing "off" here returns true,
 causing the loop attribute to always be added to the eventual HTML output
 later down the line with a value of "1".

 == Potential fix:
 - Change the working of {{{wp_validate_boolean()}}} to do as it says in
 its description. Make it smarter, and thus also return **FALSE** when the
 strings "off","OFF","no","NO", etc. are passed just like {{{filter_var(
 $var, FILTER_VALIDATE_BOOLEAN )}}} does (See this documentation link:

 - Change how the parsing of attributes happens in the [video] shortcode so
 that it also works as the documentation says: not adding certain
 attributes when they are set to "off". However there may be other
 instances where {{{wp_validate_boolean()}}} is used that I'm currently not
 aware of, so this would be more like a band-aid fix and similar issues may
 arise in the future.

Ticket URL: <https://core.trac.wordpress.org/ticket/56025>
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