Finding all records containing a specific attribute in rails

I have 2 tables in my app 1. Users, 2. Restaurants. A user can save the names (along with other attributes) of restaurants they've been to. For example user 1 has been to Panda express and Red Robins. These restaurant records also have a "food category" as an attribute of its record. When another user (user 2) lands on user 1's profile page, there's a column that lists the different restaurant food categories for user 1 (ex. American and Chinese).

What I want to be able to do is allow user 2 to click on the food categories to filter and display only restaurants under the category clicked on. (rather than show all restaurants, if user 2 clicks on Chinese, only Panda Express is displayed.)

how do I pass the food category parameter to the restaurants model to filter the results?

--

Users table: user_id | name | email

1 | Bob | bobby@email.com
2 | Alice | alice@email.com

Users restaurants table: users_restaurants_id | food_category | user_id

1 | Chinese | 1
2 | American | 1

Restaurants Table: restaurant_id | name | food_category | user_id

1 | Panda Express | Chinese | 1
2 | Red Robins | American | 1

--

Users Show view

<%= for each @restaurants do |r| %>
<%= link_to r.name, url => { :controller => users, :action => show, :xxx => r.id }
<% end %>

Users controller

def show
  @user = User.find(params[:id])
  whichfoodcategory => params(:xxx)
  unless whichfoodcategory.nil?
    #just render all restaurants for all food categories
    @restaurants = @user.restaur开发者_如何学Cants
  else
    #use the params(:xxx) to filter the restaurants model records for @user... but how?
    @restaurants = @user.filteredbyfoodcategory
  end
end

Restaurants Model
attr_accessor :xxx(?) or :whichfoodcategory(?)
named_scope :filteredbyfoodcategory { select all where user_id = 1 and food_category = :whichfoodcategory? or xxx? }

--

I'm sure I should be using named_scope in the Restaurants model, but I'm not sure how to go about passing the food category to the model.

---

Here is how you can load all the restaurants with only your existing setup.

@restaurants = @user.restaurants.all(:conditions => ["restaurants.food_category = ?", params[:xxx]])

If you want to change this into named_scopes then perhaps something like this could work:

class Restaurant < ActiveRecord::Base
  ...
  named_scope :by_food_category, lambda { |category| { :conditions => ["restaurants.food_category = ?", category] } }
end

and then in the controller:

@restaurants = @user.restaurants.by_food_category(params[:xxx])