Joe Example

find_or_create.rb

#Say we have Category and Shirt models. We have a tags join model the bind the 2 together.
# Models look like this

class Category < ActiveRecord::Base
  has_many :tags
  has_many :shirts, through: :tags
end

class Shirt < ActiveRecord::Base
  has_many :tags
  has_many :categories, through: :tags
end

class Tag < ActiveRecord::Base
  belongs_to :shirt
  belongs_to :category
end

# OK. So we want to allow users to add multiple categories to a shirt through tags. The way this is set up, it's possible
# one shirt may have the same category as another. ie

vader_breakfast = Shirt.new
vader_breakfast.categories # some magic to add the category of Star Wars here

casual_friday = Shirt.new
casual_friday.categories # Same magic here

# what's that magic look like? Well, remember that this works

star_wars = Category.create name: "Star Wars"
vader_breakfast.categories << star_wars

# lovely! The problem appears when when we want to add another shirt with the category of star wars. 
# Do we create the category again?! How do we deal with a system that sometimes has records and doesn't other times?

# Rails to the rescue

star_wars = Category.where(name: "Star Wars").first_or_create
casual_friday.categories << star_wars

# in this example, they both use the same star wars db record. http://apidock.com/rails/ActiveRecord/Relation/first_or_create

# you're dealing with a complex object but it's the same thing really, except you can pass an argument to create (Checkout the docs above)

events = facebook { |fb| fb.graph_call(event_graph_call)}
events["events"]["data"].each do |event|
  event = Event.where(fb_id: event["id"]).first_or_create(
      #notice I removed fb_id... 
    name: event["name"],
    description: event["description"],
    location_id: event["location"],
    start_time: event["start_time"],
    end_time: event["end_time"],
    ticket_uri: event["ticket_uri"],
    privacy: event["privacy"],
    cover_id: event["cover_id"],
    admin_id: event["admin_id"],
    attendee_id: event["attendee_id"],
    updated_time: event["updated_time"],
    venue_id: event["venue_id"],
    created_at: event["created_at"],
    updated_at: event["updated_at"],
    owner_id: event["owner"]["id"],
    user_id: User.last["id"])
  end
end

Ok, cool. Couple questions:

1. This isn't all in one file called find_or_create.rb, right? The class declarations at the top of the Gist would appear in their associated model.rb file, am I right? Consolidating all the code in one Gist was just so I could see and understand it better..correct me if I'm wrong.
2. On line 38 you reference a method called first_or_create but this method isn't created any where in this file. The name of this Gist is find_or_create, so is this a typo and should be referencing this file itself?
3. I was told by one of the TAs that it's important to record Facebook's ID for everything just in case I want to post to the wall of an event or send a message to a specific user (I would need the ID for that FB object to do so). When you begin creating the event variable on line 47 I see you check to see if the fb_id is the same as the event["id"]... could this check be the method first_or_create you meant to include? How do you check if fb_id matches the event["id"] if the fb_id hasn't stored anything yet?

ohhh... first_or_create is a built in method. (noted.)

Looks like you have 1 and 2 down.

I don't understand question 3