Rails: undefined method `model_name' for nil:NilClass

How exactly do I create separate pages while still able to user info from controller and model?

For example, I want to have separate pages but still using the same info from the products controller.

views/product/order.html.erb

Yet when I add a simple_form_for I get an error

<%= simple_form_for(@products) do |f| %>

Basically all I'm trying to have is a separte page to submit info for the product. If not I'd gladly be happy to do it within the same page and have a revolving simple_form like this without having to create multiple pages.

http://malsup.com/jquery/cycle/

Example:

products_controller.rb

class ProductsController < ApplicationController
 before_action :set_product, only: [:show, :edit, :update, :destroy]

def index
@products = Product.where(availability: true)
  respond_with(@products)
end


def show
end


def new
  @product = Product.new
end


def edit
  authorize! :manage, @product
end


def create
    @product = current_user.products.new(product_params)
  @product.save
  respond_with(@product)
end


def update
    authorize! :manage, @product
  respond_to do |format|
    if @product.update(product_params)
      format.html { redirect_to @product, notice: 'Product was successfully updated.' }
      format.json { render :show, status: :ok, location: @product }
    else
      format.html { render :edit }
      format.json { render json: @product.errors, status: :unprocessable_entity }
    end
  end
end

def destroy
    authorize! :manage, @product
  @product.destroy
  respond_to do |format|
    format.html { redirect_to products_url, notice: 'Product was successfully destroyed.' }
    format.json { head :no_content }
  end
end