Disable only the comment form/box itself?

Question

I'm trying to write a function which hides the comment form itself, while leaving comments and comment counts intact.

I'd like the comment form to display only when a certain parameter is in a post URL.

All I can find is code which disables everything comment related. And I came up with a method which would require some css (give form another ID when it needs to be hidden and then display: none;).

Does anyone happen to know of a PHP-only method?

Answer 1

The comments_open() function is used, both by core and typically themes to determine status for specific post. It has filter of same name for result, which you can use to manipulate it individually for the post.

comment_form() won't actually output form if check is false and fire comment_form_comments_closed action in such case.

Native WP themes, shipped with core, are also good examples of building this check into templates.

Answer 2

Here are two solutions that can be placed in functions.php. They are not really what I need, but perhaps they are of some use to someone else.

Solution 1

Can be used to close comments for certain posts:

function close_comment_form( $open, $post_id ) {
    $post = get_post( $post_id );
    if( $post->post_type == 'post' ) {
        return false;
    }
    return $open;
}
add_filter( 'comments_open', 'close_comment_form', 10 , 2 );

Solution 2

Can be used to hide the comment form via display: none; on CSS selector #HIDEcommentform:

function my_comment_form_defaults($defaults) {
    $defaults['id_form'] = 'HIDEcommentform';
    return $defaults;
}
add_filter('comment_form_defaults', 'my_comment_form_defaults');