Displaying database values in Rails?

Question

My table is:

|  1 | Electronics     | Cameras         
|  2 | Electronics     | Computers       
|  3 | Electronics     | Mobile Phone    
|  4 | Electronics     | Sound & Vision  
|  5 | Clothes         | womens clothing 
|  7 | Clothes         | women shoes     
|  8 | Clothes         | women hand bags 
|  9 | Clothes         | Mens clothing   
| 10 | Clothes         | Kids clothing

I'm trying to get a link display on my index page like this:

**Electronics**
Computers
Mobile Phone 
Sound & Vision
**Clothes**
womens clothing
women shoes 
Mens clothing

How do i do this?

My model is like this:

class Category < ActiveRecord::Base
  has_many :products
   attr_accessible :division,:subdivision
  end 


class Product < ActiveRecord::Base
        has_many :photos,:dependent => :destroy
        has_many :line_items, :through => :product_id
        belongs_to :merchant
        belongs_to  :category
        attr_accessor :quantity
        accepts_nested_attributes_for :photos, :line_items

Category table is the parent and product has a category_id. I want to display categories in the above manner, only if there are any products and my product model looks like this:

Once links display when I click on the link, I'm planning to show all the related products.

Can anyone guide me how to display the categories which have products?

This is a view issue. Can you show us what your view/controller files look like? — thank_you
– thank_you, Commented Mar 25, 2013 at 2:05
I did not create a view yet.But in my category controller looks something like this and I see the data in my show.html.erb .But I do not know how to display it on my home page index.html.erb pageclass CategoryController < ApplicationController def index @category = Category.all end — user2067515
– user2067515, Commented Mar 25, 2013 at 2:08

Unixmonkey · Accepted Answer · 2013-03-25 12:48:40Z

1

You can do this easily with Enumerable#group_by

<% Category.all.group_by{|c| c.division }.each do |division, subdivisions| %>
  <%= "**#{division}**" %><br>
  <% subdivisions.each do |subdivision| %>
    <%= subdivsion %><br>
  <% end %>
<% end %>

http://railscasts.com/episodes/29-group-by-month?view=asciicast

The block you pass to group_by gets evaluated, and every record that evaluates to the same value gets grouped together under a hash key, that you can loop over with .each

edited Mar 25, 2013 at 12:48

answered Mar 25, 2013 at 2:13

Unixmonkey

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2 Comments

Lynn Crumbling Over a year ago

You may want to add an explanation of what the code is doing, as opposed to just having a code-only answer. As-is, it was flagged as Low Quality (for review), even though it probably gives the OP a solution.

the Tin Man Over a year ago

+1@LynnCrumbling. SO wants an explanation why the code works, not just code. It's the difference between giving someone a fish, or teaching them how to fish.

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