Question

I want to narrow down a collection using params accessible through association

class PostsController < ApplicationController
load_and_authorize_resource
  def index
    if params[:event_id] then
      @event = Event.find(params[:event_id])
      if params[:category_id] then
        @category = Category.find(params[:category_id])
        @posts = Post.where(:event_id => @event.id, 
                  :product => {:category_id => @category.id })
      end
    end
  end

Gives me the error

No attribute named 'category_id' exists for table 'product'

But the column ‘category_id’ does exist in the table ‘product’. Searching for this error hasn’t shown me anything helpful yet. I’ve also tried using ‘delegate’ to make the attribute accessible but that hasn’t worked either. I’m stumped.

Here is the schema

  create_table "posts", :force => true do |t|
    t.float    "quantity"
    t.datetime "deadline"
    t.integer  "product_id"
    t.integer  "event_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "products", :force => true do |t|
    t.string   "title"
    t.text     "desc"
    t.text     "ingredients"
    t.float    "deposit"
    t.float    "cost"
    t.string   "units"
    t.float    "quantity"
    t.float    "deadline_hours"
    t.boolean  "presell_option"
    t.integer  "user_id"
    t.integer  "category_id"
    t.integer  "club_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

Edit:

When I correct ‘:product’ to ‘:products’ I get this related error

SQLite3::SQLException: no such column: products.category_id: SELECT "posts".* FROM "posts" WHERE (("products"."category_id" = 2 AND "posts"."event_id" = 10))

This puzzles me further, the schema says I do have the category_id in the products table

Answer 1

You have to use the attribute name products instead of product. This is one one Rails exceptions to the rule.

@posts = Post.joins(:product).where(:event_id => @event.id, 
                  :products => {:category_id => @category.id })