Rails 3: ActiveRecord .include not working

Really no idea what's up...

class Auction < ActiveRecord::Base
  has_and_belongs_to_many :categories
end

class Category < ActiveRecord::Base
  has_and_belongs_to_many :auctions

  default_scope order('title')
  scope :active, where(:active => true)
end

class CategoriesController < ApplicationController
  respond_to :html, :json

  # GET /categories/:id
  def show
    @category = Category.where(:id =>
params[:id]).include(:auctions).first
    respond_with(@category)
  end

end

I receive the error:

undefined method `include' for []:ActiveRecord::Relation

I have tried this on simple has_many relationships as well, and I get
nothing but this error when trying to use .include

its .includes not .include

Try following:

@category = Category.where(:id =>
params[:id]).includes(:auctions).first