Syntax to create a dependent relation?

In my controller I have this:

  def new
    @location =
    @site = @location.build_site

    respond_to do |format|
      format.html # new.html.erb
      format.xml { render :xml => @location }

  # GET /locations/1/edit
  def edit
    @location = @entity.locations(params[:id])

  # POST /locations
  # POST /locations.xml
  def create
    @site = @location.build_site(params[:site])
    @location =[:location].datebalk!)

When I return from my form I have this in params{}

"user_name"=>"A. N. Authorized-User"},
"site"=>{"site_postal_code"=>" ",
"site_street_number"=>" ",
"site_name"=>" ",
"site_building_floor"=>" ",
"site_building_name"=>" ",
"site_building_unit_number"=>" "},
"location"=>{"location_description"=>" ",

What is the correct syntax to get the hash "site" and the hash
"location" contained within the hash "params"?