How can I take advantage of my model associations in my view and controller in Ruby on Rails 3?

I am new to Rails and am trying to set up my Models and was wondering how Rails handles associations.

I have a Quest object which "belongs_to" or references via foreign keys a number of other objects, including User and Content:

quest.user_id  
quest.a_different_name_id  #this is a foreign key to a Content object

these are both foreign keys referencing a User object and Content object respectively.

Both User and Content "has_many" Quests.

I understand that this setup allows me to do things like:

u = User.create #saves to database  
u.quests.build  #creates new Quest object with user id set to u.id  

Can I do something in the opposite direction like:

form_for @quest do |f|
    f.text_field :a_user_attribute            #an attribute of a User object
开发者_Go百科    f.text_field :a_different_name_attribute  #an attribute of a Content object

where the form has text fields for the attributes of the objects which a Quest object references through its foreign keys as opposed to having a form for the actual foreign keys, so that when in the controller I have:

@quest = Quest.new(params[:quest])

Is Rails smart enough to "reach through" the model-defined foreign key relationships and populate and then save the User and Content objects and appropriately set the foreign keys in @quest to reference the newly created objects?

Can it do this even though the foreign key for the Content object has a different name than content_id?

Hope this makes sense... let me know if I am being unclear.

You can do what you need with the Nested Attributes feature in Rails http://guides.rubyonrails.org/2_3_release_notes.html#nested-attributes

Check out the form helper for it here http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html

Basically you would need to do the following:

class User < ActiveRecord::Base
  has_many :quests
  accepts_nested_attributes_for :quests
  ...
end

class Quest < ActiveRecord::Base
  belongs_to :user
  ...
end

then in the form you do the following:

<%= form_for @user do |f| %>
  UserAttrA  : <%= f.text_field :a_user_attribute_a %>
  UserAttrB: <%= f.text_field :a_user_attribute_b %>
  <%= f.fields_for :quests do |qf| %>
    QuestAttrA  : <%= qf.text_field :a_quest_attribute_a %>
    QuestAttrB: <%= qf.text_field :a_quest_attribute_b %>
  <% end %>
  UserAttrC  : <%= f.text_field :a_user_attribute_c %>
  UserAttrD: <%= f.text_field :a_user_attribute_d %>
<% end %>

And your controller would work just like you have above.

Note that you can display User inputs before and/or after Quest inputs. Basically you can make the form in the view look how you want. But the semantics on the server will be need to be consistent.