Errata for Developing Facebook Platform Applications with Rails

#36148: The set_current_user method in app/controllers/application.rb needs to be updated to pass in a second facebook_session parameter otherwise the session_key value in the users table will always be null:

Before:
def set_current_user
self.current_user = User.for(facebook_session.user.to_i)
end

After:
def set_current_user
self.current_user = User.for(facebook_session.user.to_i, facebook_session)
end

This problem is not present in the downloadable code, just in the printed book.--Paul Fioravanti

#40954: The book suggests that a 64-bit integer is created with ActiveRecord by applying a :limit =>20 argument. This is incorrect. ActiveRecord uses the "limit" argument to describe the number of *bytes* for a binary or integer column. The correct limit value for triggering MySQL to set a given column as being BIGINT is 8. So the line from the book should read:

t.integer :facebook_id, :limit => 8, :null => false--Trevor Rosen

#38161: The method User#for calls #create_by_facebook_id . However, that method doesn't exist. The method should call #find_or_create_by_facebook_id .

See "Dynamic attribute-based finders" at api.rubyonrails.org/classes/ActiveRecord/Base.html--Nick Hoffman

#38164: The book should explicitly state that all before-filters that rely on Facebooker methods and variables must be defined after the call to #ensure_authenticated_to_facebook .
--Nick Hoffman

#39999: In the linked example code for application.rb:

self.current_user = User.for(facebook_session.user.to_i, facebook_session)

it shows ",facebook_session" but no where in the book does it show to add that. Therefore, when the book says, "we’ll need to visit our application in a web browser to set our session key" that won't actually happen.--Peter T Bosse II

#38171: The #hometown method should check that the "location" variable isn't blank/nil before calling "location.city" and "location.state". See pastie.org/407507 .
--Nick Hoffman

#42089: profile_expection has changed slightly. I had to cut and paste the error from the flexmock exception: "<fb:fbml>\n\tI was sent here by <fb:name uid='1' />\n</fb:fbml>\n"--Bill Gathen

#37202: In both code samples, shouldn't we add attack.save before the create method ends? Otherwise, no attack is saved to the database (and the text explicitly mentions so). Either the code is wrong, or the description is wrong, and I think saving them makes sense (perhaps not in this case, but in general, make sense saving the models)--victor jalencas

#36150: The generate publisher command has apparently changed:

Before:
script/generate publisher attack

After:
script/generate facebook_publisher attack--Paul Fioravanti

#36238: I found that in the code for new.erb the new_attack_path method needs to be substituted for a new_attack_url method otherwise there will be routing errors when an invite is accepted.--Paul Fioravanti

#36159: Under the fb_request_form method, there is a fb_request_form_submit method.
This is not needed as the fb_multi_friend_selector method already provides a submit button as well as a skip button (the code in the book renders two submit buttons to screen). It would be needed if the friend selector was just a standard fb_friend_selector.--Paul Fioravanti

#36311: The select nickname function in Karate Poke doesn't work properly on Firefox.

Textbook code for app/views/attacks/index.fbml.erb
...
<div id="nickname">
<%= render :partial=>"users/nickname",
:locals=>{:closed => !current_user.nickname.blank?} %>
</div>
...
Textbook code for app/views/users/_nickname.erb

...
<% remote_form_for :user,
current_user,
:url => user_url(:id=> current_user, :canvas=> false),
:html => {:method => :put},
:update => "nickname" do |f| %>
Select a nickname to show outside of Facebook
<%= text_field_tag :nickname, current_user.nickname %>
<%= submit_tag "save" %>
<% end %>
...
When attacks/index is rendered to HTML, we get these two elements:
<div id="[facebook_app_id]_nickname">
<input id="[facebook_app_id]_nickname"> (from <%= text_field_tag :nickname, current_user.nickname %>)
I guess this is where Firefox gets tripped up: even though the elements are of a different type, they have the
same id.

So, I managed to get the page working as expected in Firefox by changing the name of the <div> id and the
:update value in the remote_form_for method. Either that, or change the name of the :nickname
symbol in _nickname.erb and app/controllers/users_controller.rb--Paul Fioravanti