Question

I’m integrating Facebook into an app that uses a page’s feed for some of its content.

I’d like to be able to allow users to comment on the post and see the previous comments left on that post.

If possible, I’d love to avoid having to build my own implementation of the commenting system (not to mention having to implement an oauth login for users to comment), and just use the comment widget provided by Facebook (see here: http://developers.facebook.com/docs/reference/plugins/comments/)

Is it possible to use the above comment plugin to not reference an arbitrary link, but an actual (public) post on a Facebook page?

Answer 1

No, it’s not possible to have the Comments Plugin point to an on-facebook.com URL; it’s only supported when it points to websites.

To achieve what you want (something on your site which can add comments to a Post on facebook.com, yes?) you’d need to get the users to authorise an app you write, which takes their input and posts it on their behalf back to Facebook via the API

The actual implementation of that would vary depending on your exact requirements, but basically you’ll want to:

• Have your users authorise the app when on your page; Client side in Javacript or Server-side via redirects
• Note that you’ll need to include the publish_actions or publish_stream publishing Permission
• POST a comment to the Post object‘s ‘comments’ connection

Example in Javascript SDK
Once the user is logged in and has granted those permissions, this adds a comment to the post (visible here: http://www.facebook.com/155965101083460/posts/155965104416793 )

FB.api(
    "/155965101083460_155965104416793/comments",
     {message: 'This is great, thanks!'},
     'POST'
 );