How to use pre_comment_user_agent filter in WordPress

pre_comment_user_agent filter

Filters the comment author’s browser user agent before it is set.

To use pre_comment_user_agent filter, you first need to register it using add_filter. You can include this code in the functions.php file of your activated theme or in a custom WordPress Plugin.

At WePlugins, we always recommend creating a custom WordPress Plugin when using hooks to ensure nothing breaks when you update your WordPress Theme in the future.

In the live example below, we define a function weplugins_modify_pre_comment_user_agent_defaults which takes one parameter. We register it using add_filter. The first parameter pre_comment_user_agent is the name of the hook, the second parameter weplugins_modify_pre_comment_user_agent_defaults is the name of the function to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed to the registered function.

Sometimes, you may need to remove a registered hook, and you can use remove_filter to remove the pre_comment_user_agent filter.

Parameters

Below is the 1 parameter required to use this hook.

• $comment_agent: (string) The comment author’s browser user agent.

Example 1: Basic Usage

Below is an example of how you can use this hook.

    function weplugins_modify_pre_comment_user_agent_defaults($comment_agent) { 
        // Update the $comment_agent variable according to your website requirements and return this variable. You can modify the $comment_agent variable conditionally too if you want.
        return $comment_agent; 
    }
    // add the filter
    add_filter( "pre_comment_user_agent", "weplugins_modify_pre_comment_user_agent_defaults", 10, 1 );
    

Example 2: Removing the Hook

To remove a hook callback, use the example below.

    remove_filter( "pre_comment_user_agent", "weplugins_modify_pre_comment_user_agent_defaults", 10, 1 );
    

Please make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.

Example 3: Advanced Customization

Here’s a more advanced example where you might want to modify the user agent string based on specific conditions.

    function weplugins_advanced_modify_pre_comment_user_agent($comment_agent) {
        if (strpos($comment_agent, 'Chrome') !== false) {
            $comment_agent .= ' - Modified by WePlugins';
        }
        return $comment_agent;
    }
    add_filter( "pre_comment_user_agent", "weplugins_advanced_modify_pre_comment_user_agent", 10, 1 );
    

Contact Us

If you’re having any trouble using this hook or need customization, please contact us and we’d be happy to assist you.