Question

I have an application where I have added a sidebar with a list of all the categories the products belong to.

The feature works fine but there is a problem.

The code only scans through the products on the current page and not the actual categories available. That is:

In my application there are say 5 categories (which there are) of products but on the current page there are only 3 products. So the code only shows me 3 categories and not the actual 5.
How can I fix this? Does this have anything to do with instance variables?

Here is the code from application.html.erb

<div>
  <% a = [""] %>
    <h1>Categories</h1>
    <% @products.each do |product| %>
    <% a = a + [product.category] %>
    <% a = a.uniq %>        
  <% end %>

  <% a.each do |c| %>
     <p class="text-error"><%= c %></p>
  <% end %>
</div>

Migration files..

class CreateProducts < ActiveRecord::Migration
   def change
     create_table :products do |t|
       t.string :name
       t.text :description
       t.date :delivery_date
       t.decimal :price

       t.timestamps
    end
   end
 end

 class CreateCommentsTable < ActiveRecord::Migration
  def up
    create_table :comments do |t|
      t.string :commenter
      t.text :body
      t.references :product

      t.timestamps
    end
    add_index :comments, :product_id
  end

  def down
  end
 end


 class AddCategoryToProducts < ActiveRecord::Migration
   def change
     add_column :products, :category, :string
   end
end

Routes..

resources :products do
    resources :comments 
end

The code is available at https://github.com/abhishekdagarit/sample-app.git

Might take u people just a quick look to answer this…

Answer 1

If you have separate Category model mapped to categories table then Category.select(:name).uniq would have return unique categories.

In your case you have category column withing the table. So in that case

Product.select(:category).uniq would return list of Products with unique categories.

So now you template would be cleaner with:

<% for product in Product.select(:category).uniq %>
   <%= product.category %>
<% end %>