How to hide a field in a comment in hook_comment_view programatically?

Question

My comments have a field called 'Extra'. I'm trying to hide it when the user who's viewing the comment wrote it. This is my custom module:

function mymodule_comment_view($comment) {
  global $user;
  if ($comment->uid == $user->uid){
    unset ($comment->field_extra);
  }
}

Why isn't this working and what's the correct way to achieve my goal?

Answer 1

Looking at the same kind of functionality in the user.module function user_comment_view() I would expect your code to work.

If your function is really called hook_comment_view then it won't work though. Either this is just a typo, or rename your function to MYMODULE_comment_view where MYMODULE is the name of your custom module.

Edit: After a little discussion with MPD it turns out, that this actually works:

$comment->content['field_extra']['#access'] = FALSE;

Respect to MPD for explanations and an inside for why that could work and especially for why the other solution doesn't work!

This is the phrase from MPD that lead to the solution:

If you read the source for comment_build_comment(), $comment->content[] has already been built up by the time the view hook gets invoked. So, messing with the field directly has no effect at this point.

Which means, that the field output has already been built and stored in $comment->content, which implies that this follows the same rules as in hook_node_view(). So accessing $comment->content[FIELD_NAME] should work.

Answer 2

hook_comment_view(), along with most of the other entity view hooks, are typically used to add properties onto the entity object.

If you read the source for comment_build_comment(), $comment->content[] has already been built up by the time the view hook gets invoked. So, messing with the field directly has no effect at this point.

You want to implement a template_process_comment() in your theme, or you can implement a module (which technically makes it an instance of hook_preprocess_comment().

Implement this, and then dpm($variables) inside it. Figure out what you don't want, and then unset() it. If the variable is printed directly from the comments template, this is is directly in $variables. If it is in the content section, then unset the proper key in $variables['content'], which is a render tree.