Facebook Like Box: How to detect if user already liked the page?

I have installed the Like Box in my blog, and I want to know if the user already like my page. I want to implement something like this to my reader because I want to offer them hidden contents if they already liked my page.

Is there a开发者_运维技巧n event where I will detect if the user already liked the page in the Like Box?

If you are using the XFBML version of the Like Box, you can subscribe to the 'edge.create' event through FB.Event.subscribe.

As Kendall points out, the edge.create event only fires if they like the page while you're listening for it.

Here's another approach that parses the $_REQUEST['signed_request'] parameter that Facebook sends to every page tab app. One of the attributes encoded in the signed_request is if the user has liked the page or not.

Pretty slick.