how to check if the user likes the given url/id of the page or not.

like_check.rb

@client = Koala::Facebook::API.new(access_token)

# Check if the user likes the given url or not.
url = "http://example.com"
@client.fql_query("SELECT url FROM url_like WHERE user_id=me()").map do |like|
  like["url"]
end.include?(url)

# Get how many likes the url got.
@client.fql_query("SELECT like_count FROM link_stat WHERE url=\"#{url}\"")["like_count"]

# Check if the user likes the page specified by the id or not.
page_id = 19765981
@client.fql_query("SELECT uid FROM page_fan WHERE page_id=#{page_id} and uid=me()").present?

@client.fql_query("SELECT url FROM url_like WHERE user_id=me()")
can be improved
@client.fql_query("SELECT url FROM url_like WHERE user_id=me() AND url=\"#{url}\"")