Adding Extra Fields to WordPress Comments

WordPress comes built in with a full featured, robust commenting system. If you write a blog, you probably want to interact with your readers. Comments give you a way to do that.

But WP’s built in comments might come in handy for other purposes. For instance, if you’re running a small ecommerce store on WordPress, you could use the commenting system to do customer reviews. You could also turn the comments into a sort of forum.

This tutorial is not going to be about specific usage, but, rather, a general how to for adding fields to comments on both the front end and back end of WordPress. We’ll be using the default Twenty Eleven theme here.

A few versions back WordPress standardized the comments form for theme authors with the creatively named 

comment_form

We’re going to use a few of those hooks: comment_form_logged_in_after and comment_form_after_fields. They will add something after the “You’re logged in as…” message or the name, email and website fields respectively.

We’ll just call add_action for each of our hooks and in our hooked function spit out form code we want.

<?php

add_action(‘comment_form_logged_in_after’,‘pmg_comment_tut_fields’);

add_action(‘comment_form_after_fields’,‘pmg_comment_tut_fields’);

functionpmg_comment_tut_fields()

{

    ?>

    <pclass=“comment-form-title”>

        <label for=“pmg_comment_title”><?php_e(‘Title’);?></label>

        <input type=“text”name=“pmg_comment_title”id=“pmg_comment_title”/>

    </p>

    <?php

}

Because we’re using Twenty Eleven, let’s hook into wp_head and spit out some CSS to prettify our form field. This is copied straight from the Twenty Eleven stylesheet adapted to our selector.

<?php

add_action(‘wp_head’,‘pmg_comment_tut_style_cheater’);

functionpmg_comment_tut_style_cheater()

{

    ?>

    <style type=”text/css”>

        #respond .comment-form-title {

            position:relative;

        }

        #respond .comment-form-title label {

            background:#EEE;

            -webkit-box-shadow:1px2px2pxrgba(204,204,204,0.8);

            -moz-box-shadow:1px2px2pxrgba(204,204,204,0.8);

            box-shadow:1px2px2pxrgba(204,204,204,0.8);

            color:#555;

            display:inline-block;

            font-size:13px;

            left:4px;

            min-width:60px;

            padding:4px10px;

            position:relative;

            top:40px;

            z-index:1;

        }

    </style>

    <?php

}

The comments editing screen in the WordPress admin area is just like any other editing screen: you can add meta boxes to display and save additional data. You can check out this tutorial for a general overview of adding meta boxes.

First we’ll need to add our meta box with a function hooked into add_meta_boxes_comment and a call to 

add_meta_box

<?php

add_action(‘add_meta_boxes_comment’,‘pmg_comment_tut_add_meta_box’);

functionpmg_comment_tut_add_meta_box()

{

    add_meta_box(‘pmg-comment-title’,__(‘Comment Title’),‘pmg_comment_tut_meta_box_cb’,‘comment’,‘normal’,‘high’);

}

functionpmg_comment_tut_meta_box_cb($comment)

{

    $title=get_comment_meta($comment->comment_ID,‘pmg_comment_title’,true);

    wp_nonce_field(‘pmg_comment_update’,‘pmg_comment_update’,false);

    ?>

    <p>

        <label for=“pmg_comment_title”><?php_e(‘Comment Title’);?></label>

        <input type=“text”name=“pmg_comment_title”value=“<?phpechoesc_attr($title);?>“class=“widefat”/>

    </p>

    <?php

}

Next up, we need to actually take care of saving the title for our comment. We’ll need to do this in two places: the front end form and the admin area meta box.

When WordPress outputs a comment form, it does so with a file called 

wp-comments-post.php

wp_new_comment

update_comment_meta

<?php

add_action(‘comment_post’,‘pmg_comment_tut_insert_comment’,10,1);

functionpmg_comment_tut_insert_comment($comment_id)

{

    if(isset($_POST[‘pmg_comment_title’]))

        update_comment_meta($comment_id,‘pmg_comment_title’,esc_attr($_POST[‘pmg_comment_title’]));

}

For the admin area, we need to do a bit more work. First we’ll verify our nonce, then check and make sure our title is set and update it if it is.

<?php
add_action(‘edit_comment’,‘pmg_comment_tut_edit_comment’);
functionpmg_comment_tut_edit_comment($comment_id)
{
if(!isset($_POST[‘pmg_comment_update’])||!wp_verify_nonce($_POST[‘pmg_comment_update’],‘pmg_comment_update’))return;
if(isset($_POST[‘pmg_comment_title’]))
update_comment_meta($comment_id,‘pmg_comment_title’,esc_attr($_POST[‘pmg_comment_title’]));
}

Now it’s time to actual show the comment titles on the front end. There are two ways one could do this:

1. Include a call to 

get_comment_meta

wp_list_comments

2. Hook into the comment_text filter, grab the comment title with get_comment_meta, then add it to the comment text before sending it out.

We’ll use the second option in this case. We’ll hook into comment_text, first checking to see if we’re in the admin area. If we are, return the content straight away. Next we’ll try to get our comment title. If it’s there, we’ll add it to the text. Then we send the comment text back out.

WordPress uses its own plugin API to do several things within the core. Namely, it adds certain filters to your post content text and comment text. We need to call our comment_text filter way late to ensure it doesn’t step on any of those built in filters toes (or, rather, that those default filters don’t screw up our formatting). This is done with the third argument of add_filter. The higher the number, the later, the function is called. If you want to see how the WP core uses its own hook system, check out 

wp-includes/default-filters.php

<?php

add_filter(‘comment_text’,‘pmg_comment_tut_add_title_to_text’,99,2);

functionpmg_comment_tut_add_title_to_text($text,$comment)

{

    if(is_admin())return$text;

    if($title=get_comment_meta($comment->comment_ID,‘pmg_comment_title’,true))

    {

        $title=‘<h3>’.esc_attr($title).‘</h3>’;

        $text=$title.$text;

    }

    return$text;

}

The entire code for this article is available as a plugin.