Using WordPress ‘pre_comment_content’ PHP filter

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pre_comment_content is a WordPress PHP filter that allows you to modify the comment content before it is saved in the database.

Usage

add_filter('pre_comment_content', 'your_custom_function', 10, 1);

function your_custom_function($comment_content) {
    // your custom code here

    return $comment_content;
}

Parameters

  • $comment_content (string): The comment content to be filtered.

More information

See WordPress Developer Resources: pre_comment_content

Examples

Remove HTML Tags

Strip all HTML tags from the comment content.

add_filter('pre_comment_content', 'remove_html_tags', 10, 1);

function remove_html_tags($comment_content) {
    $comment_content = strip_tags($comment_content);

    return $comment_content;
}

Replace Bad Words

Replace specific bad words with asterisks.

add_filter('pre_comment_content', 'replace_bad_words', 10, 1);

function replace_bad_words($comment_content) {
    $bad_words = array('badword1', 'badword2');
    $replacement = '*****';

    $comment_content = str_ireplace($bad_words, $replacement, $comment_content);

    return $comment_content;
}

Automatically convert URLs within the comment content to clickable links.

add_filter('pre_comment_content', 'convert_urls_to_links', 10, 1);

function convert_urls_to_links($comment_content) {
    $comment_content = make_clickable($comment_content);

    return $comment_content;
}

Add a Signature

Automatically add a signature to the end of each comment.

add_filter('pre_comment_content', 'add_signature', 10, 1);

function add_signature($comment_content) {
    $signature = ' -- Thanks for commenting!';
    $comment_content .= $signature;

    return $comment_content;
}

Limit Comment Length

Limit the comment content to a specific number of characters.

add_filter('pre_comment_content', 'limit_comment_length', 10, 1);

function limit_comment_length($comment_content) {
    $max_length = 200;
    $comment_content = mb_substr($comment_content, 0, $max_length);

    return $comment_content;
}