button_to not passing correct id from params hash

The button_to is not passing the correct id to the line_item. In the log below you see the bike_id change from the correct '86' to the incorrect '1' (which coincidentally is my user_id). Any help would be appreciated. Below is the error from my development.log, then the code from my view and controllers. Thanks.

development.log

Started POST "/line_items?bike_id=86" for 127.0.0.1 at 2011-08-01 18:09:52 -0400

DEPRECATION WARNING: Setting filter_parameter_logging in ActionController is deprecated and has no longer effect, please set 'config.filter_parameters' in config/application.rb instead. (called from <class:ApplicationController> at /Users/willdennis/rails_projects/spinlister/app/controllers/application_controller.rb:8)

Processing by LineItemsController#create as HTML

Parameters: {"authenticity_token"=>"5GYQqvf7U5awhLrZ9Aw910ETf2kqOk3PI315jkjEfMU=", "bike_id"=>"86"}

[1m[35mCart Load (0.6ms)[0m SELECT "carts".* FROM "carts" WHERE ("carts"."id" = 8) LIMIT 1 [1m[36mBike Load (1.2ms)[0m [1mSELECT "bikes".* FROM "bikes" WHERE ("bikes"."id" = 86) ORDER BY bikes.created_at DESC LIMIT 1[0m [1m[35mSQL (0.5ms)[0m INSERT INTO "line_items" ("bike_id", "cart_id", "created_at", "updated_at") VALUES (1, 8, '2011-08-01 22:09:53.208978', '2011-08-01 22:09开发者_如何学编程:53.208978') [1m[36mCart Load (1.5ms)[0m [1mSELECT "carts".* FROM "carts" WHERE ("carts"."id" = 8) LIMIT 1[0m Redirected to http://localhost:3000/carts/8 Completed 302 Found in 251ms

line_items_controller.rb

def create
 @cart = current_cart
 @bike = Bike.find(params[:bike_id])
 @line_item = @cart.line_items.build(:bike_id => @bike)
 respond_to do |format|
    if @line_item.save
      format.html { redirect_to(@line_item.cart,
      :notice => 'Line item was successfully created.') }
      format.xml { render :xml => @line_item,
      :status => :created, :location => @line_item }
    else
      format.html { render :action => "new" }
      format.xml { render :xml => @line_item.errors,
      :status => :unprocessable_entity }
    end
  end
end

views/bikes/show

<%= button_to "Rent this Bicycle!", line_items_path(:bike_id => @bike), {:id => "rentthisbike"} %>

bike.rb

class Bike < ActiveRecord::Base
 belongs_to :user
 has_many :line_items
 attr_accessible :name, :description, :size, :biketype, :price, :photo, :id, :address, :city, :state, :zip, :latitude, :longitude, :neighborhood, :bike_id
end

line_item.rb

class LineItem < ActiveRecord::Base
  belongs_to :bike
  belongs_to :cart

  accepts_nested_attributes_for :bike, :cart

  attr_accessible :bike_id, :bike, :cart, :name, :description, :size, :biketype, :price, :photo, :id, :address, :city, :state, :zip, :latitude, :longitude, :neighborhood 

end

cart.rb

class Cart < ActiveRecord::Base
 has_many :line_items, :dependent => :destroy
 belongs_to :user

 accepts_nested_attributes_for :line_items

 attr_accessible :bike_id, :line_items, :name, :description, :size, :biketype, :price, :photo, :id, :address, :city, :state, :zip, :latitude, :longitude, :neighborhood 
end

Can you try this code and post the @@@@ Line item attributes entry from your log file along with the params hash I think this may be related to your current_cart method but I'm not sure

line_items_controller.rb

def create
 @bike = Bike.find(params[:bike_id])
 @line_item = current_cart.line_items.build
 @line_item.bike = @bike
 logger.debug("@@@@ Line item attributes = #{@line_item.inspect}")
 respond_to do |format|
    if @line_item.save
      format.html { redirect_to(@line_item.cart,
      :notice => 'Line item was successfully created.') }
      format.xml { render :xml => @line_item,
      :status => :created, :location => @line_item }
    else
      format.html { render :action => "new" }
      format.xml { render :xml => @line_item.errors,
      :status => :unprocessable_entity }
    end
  end
end

Update.

Your previous code was fine except for this line @line_item = @cart.line_items.build(:bike_id => @bike) You were supplying the whole class as the value for the bike ID instead of the id of the bike. I know this is inconsistent with passing form parameters but that's just the way it is.