Rails associations / sessions question

I am working on a app for my kid开发者_Go百科s to log their chores. I have 3 children (Nick, Siena, Mac) and have a home page with each name hyperlinked ...

I have the following associations:

Child:
  has_many :completions
  has_many :chores, :through=>:completion

Completion: 
  belongs_to :child
  belongs_to :chore

Chore:
  has_many :completions
  has_many :kid, :through=>:completion

1. How do I (upon clicking the child's name) save the child_id as a session object for posting completions to the completions models?

2. How do I clear / change that sesison to a new child when another child clicks their name in the homepage?

Any help is greatly appreciated. Thanks, CB

So josh went above and beyond. As a noob i was asking something much more simple and elementary for most folks. The answer was quite simple:

ApplicationController

private
  def current_child
    child = Child.find(params[:id])
    session[:child_id] = child.id
  end
end

This allowed me to store that child's id in a session and post to the completed model.

If I understand the question correctly (at least as described in your comment), I did something similar recently. See Building a nested attribute from multiple parent objects. Basically, I used polymorphic_url to make a link to create a new item (I would probably use @child.chores.build(params)) and pass the attribute :chore_id, i.e.

link_to "Mark as complete", polymorphic_url([:new, @child, :completion], :chore_id => @chore.id)

In your controller make sure that for your ChoresController#new you have something like

def new
  @chore = <current_child>.chores.build(params)
end

Hope this helps.