Looking for the filter hook for the admin/comments/reply to process (where you use 'reply to' in the comments administration screen). This will be used in a custom plugin.

(The plugin adds a hidden field to a front-end entered comment to reduce bot-entered comments. The extra field is inserted properly on the front end, but not in the admin comment list page.)

I need to

  • add a hidden field to the comment drop-down on the comments admin list (the comment field that shows when you click the 'reply' link for a comment).
  • add some pre-processing to the comment drop-down when it is submitted and before WP processes the comment.

Not sure where to start on this, although I think it is in https://developer.wordpress.org/reference/files/wp-admin/includes/class-wp-comments-list-table.php/ .

Am I on the right track? Is there a filter for the adding of fields to the comment box form that is on the admin/comments page?

(Note: had posted this question in StackExchange main area by mistake. And got a down-vote and close vote without explanation for my efforts. So duplicating the question here - where I meant to put it.)


The hidden field is added to the comment form on the front end with the 'add_meta_boxes_comment' action hook, which uses the 'add_meta_box' function to specify the field and the callback function for that inserted/hidden field.

The hidden/added field is processed via the 'edit_comment' hook. If the hidden field is not there, then the comment is not saved.

This works fine in the front-end, but the hidden/added field is not added to the comment form in the back-end's "Reply" on the comment list page.

  • 1. "add a hidden field" - you mean, a hidden field with a value that remains unchanged on the same page, regardless which comment being edited or replied to? 2. "add some pre-processing" - what kind of pre-processing? How did you do that on the front-end side (what hook you used)?
    – Sally CJ
    Jan 20, 2022 at 7:33
  • 1
    Added additional info to the question per the request of the above comment. Jan 20, 2022 at 22:46
  • So I wondered if my answer answered your question, either in full or just partially? Could you please let me know?
    – Sally CJ
    Jan 24, 2022 at 9:06
  • 1
    Your answer was helpful, but I decided to do it differently to reduce complexity. My solution (below) worked for my application. My solution might help others, but so will your answer. Jan 24, 2022 at 19:06

2 Answers 2


Is there a filter for the adding of fields to the comment box form that is on the admin/comments page?

If you meant the inline form for editing or replying to a comment at wp-admin/edit-comments.php, then,

  • The form is outputted using wp_comment_reply() which has a hook with the same name, i.e. wp_comment_reply, and you could use that to return your own comment reply form HTML.

  • However, the inline editing is a JavaScript feature, hence I would simply use JS to add custom fields to that form.

Working Example

So here's a sample script for adding a field named hidden_field (labeled Hidden Field) to that form:

jQuery( function ( $ ) {
    // Append the field at the bottom of the inline form, above the submit
    // button. Just customize the HTML, but ensure the selector is correct.
    // ( i.e. I used [name="hidden_field"], so change it based on your HTML. )
    $( '#replysubmit' ).before(
        '<p style="padding: 3px 0 2px 5px; clear: both">' +
            '<label>Hidden Field:</label> ' +
            '<input name="hidden_field" />' +

    // Note: (window.)commentReply is defined by WordPress.
    $( '#the-comment-list' ).on( 'click', '.comment-inline', function() {
        var $field = $( '#replyrow input[name="hidden_field"]' );

        // If the Quick Edit button is clicked, set the field value to the
        // current database value.
        if ( 'edit-comment' === commentReply.act ) {
            $field.val( $( '#hidden_field-' + commentReply.cid ).val() );
        } else {
        // If the Reply button is clicked, then we empty the field.
            $field.val( '' );
    } );

    // Submit the form when the Enter key is pressed.
    $( '#replyrow input[name="hidden_field"]' ).on( 'keypress', function( e ) {
        if ( e.which == 13 ) {
            return false;
    } );
} );
  1. Save it to an external JS file and load the script on the comments page, e.g. via the admin_enqueue_scripts hook, like so: ( make sure admin-comments which loads wp-admin/js/edit-comments.js, is in the dependencies list )

    add_action( 'admin_enqueue_scripts', 'my_admin_enqueue_scripts' );
    function my_admin_enqueue_scripts() {
        if ( 'edit-comments' === get_current_screen()->id ) {
            wp_enqueue_script( 'my-script', '/path/to/the/script.js',
                array( 'admin-comments' ) );
  2. To save the field, e.g. as a comment metadata, you can use the comment_post and (the one you already using) edit_comment hooks. For example:

    add_action( 'edit_comment', 'my_save_comment_hidden_field' ); // for the Quick Edit button
    add_action( 'comment_post', 'my_save_comment_hidden_field' ); // for the Reply button
    function my_save_comment_hidden_field( $comment_ID ) {
        if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
        if ( ! isset( $_POST['hidden_field'] ) ||
            ! current_user_can( 'edit_comment', $comment_ID )
        ) {
        $value = sanitize_text_field( $_POST['hidden_field'] );
        update_comment_meta( $comment_ID, 'hidden_field', $value );
  3. Make sure to add a hidden input which stores the field value that's currently in the database. But it does not have to be an <input />.. you could just use other element; what's important is, store the value somewhere so that JS can get the value and update the field value in the inline form when editing a comment, i.e. after clicking on "Quick Edit".

    So for example, I added the hidden input via the comment_text hook:

    add_filter( 'comment_text', 'my_comment_text', 10, 2 );
    function my_comment_text( $comment_text, $comment ) {
        $value = $comment ? get_comment_meta( $comment->comment_ID, 'hidden_field', true ) : '';
        $input = sprintf( '<input type="hidden" id="hidden_field-%d" value="%s" />',
            $comment->comment_ID, esc_attr( $value ) );
        return $comment_text . $input;

Although @SallyCJ's answer might work, and is probably good information, I went in a different direction that worked for my application.

My application needs a hidden field in the comment form. Although you can easily add the hidden field to the front-end comment form, the back-end doesn't use that process. But my application needs the POST of that hidden value for a verification process.

Since the hidden field isn't easily insertable in the back-end drop-down comment form (that you get when you hit the reply button), I reasoned that only an authorized admin can get to the admin/comment list, so my application doesn't need to check if it is a bot accessing the comment form. (My plugin senses bot comment submissions.) If you are logged in as an admin, then you are not a bot.

So, in the section that checks for the hidden field, I added this to add the GUID value to 'the_hidden_field' that is shown on the front-end comment form:

if (current_user_can( 'moderate_comments' ) ) {
     // forces the guid on admin/comment replies without needing
     //    to add a hidden field to the dropdown form.
    $_POST['the_hidden_field'] = wp_generate_uuid4(); 
    return $commentdata;

The 'if' statement will be true for the admin/editor/author roles only, so the hidden field is sort of added to the comment POST.

Note that others have said that you can use is_admin() to see if you are in an admin page, but that returns false in some instances - like if you are in the admin/list comments page, and you hit the 'reply' button for a comment. An is_admin() check there returns false. So that didn't work.

Adding the code above resolved my issue. Might not work for all - you may need the code suggested by @SallyCJ . But it worked for me.

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