Question

I have a design model, which allows designers to upload a design they have made. I would like to query for designs with the same title, uploaded by the same designer and group them together.

I can’t get my head around on how do I do this in. Do you have a suggestion?

I run Rails 3.2, Ruby 1.9.3 and Mongoid.

More info:

Designers model:

class Designer
    has_many :designs, :order => "created_at"
end

Designs model:

class Design
    belongs_to :designer

    attr_accessible :image,  :tags, :description, :title, :featured

    mount_uploader :image, DesignerUploader

    field :width
    field :height
    field :description
    field :title
    field :tags, type: Array
    field :featured, :type => Boolean, :default => false
end

Designs controller:

def newest
    @designs = Design.select("title, count(title) as title_count").group(:title).having("title_count > 1")
end

I have a designer who can upload a lot of designs. If he uploads designs with the same title, they should be grouped together (I’m thinking the best way for this would be to create an array inside an array). I don’t know how to query for this in the database. Any ideas?

EDIT

I think I need something similar to this:

Design.find(:all, :group => [:title], :having => "count(*) > 1" )

This should give me a single instance of all the duplicates titles. When I have that, I can query for those titles and put them in a nested array or something like that.

Problem is that I don’t know how you can make this query in mongoid?!

Answer 1

Your models are significantly incomplete, so please accept the following working solution as an attempt to remain close to your models, and the answer as just a suggestion for moving ahead.

class Designer
    include Mongoid::Document
    field :name, type: String
    has_many :designs #, :order => "created_at"
end

class Design
    include Mongoid::Document
    belongs_to :designer

    attr_accessible :image, :tags, :description, :title, :featured

    #mount_uploader :image, DesignerUploader

    field :width, type: Integer
    field :height, type: Integer
    field :description, type: String
    field :title, type: String
    field :tags, type: Array
    field :featured, type: Boolean, default: false
end

class DesignsController < ApplicationController
  def newest
    @designer = Designer.where(name: params['name']).first
    @designs = Design.where(designer_id: @designer._id).where(title: params['title']).to_a
    render :text => <<-EOF
      params: #{params.inspect}
      designer: #{@designer.inspect}
      designs by title: #{@designs.inspect}:
    EOF
  end
end

config/routes.rb

match ':controller/:action/:name/:title'

test/unit/designer_test.rb

require 'test_helper'

class DesignerTest < ActiveSupport::TestCase
  def setup
    Designer.delete_all
    Design.delete_all
  end

  test "designer designs" do
    design_title = 'little black dress'
    designer = Designer.create(name: 'Coco', designs: [
      Design.new(title: design_title, width: 300, height: 400),
      Design.new(title: design_title, width: 600, height: 800),
      Design.new(title: 'jersey traveling suit', width: 600, height: 800),
    ])
    p designer

    # finds designs with designer and title on server
    designs = Design.where(designer_id: designer._id).where(title: design_title).to_a
    assert_equal(2, designs.size)
    p designs

    # finds all designer's designs and selects locally
    designs = designer.designs.select{|design| design['title'] == design_title}
    assert_equal(2, designs.size)
    p designs
  end
end

test/functional/designs_controller_test.rb

require 'test_helper'

class DesignsControllerTest < ActionController::TestCase
  def setup
    Designer.delete_all
    Design.delete_all
  end

  test "newest" do
    design_title = 'little black dress'
    designer = Designer.create(name: 'Coco', designs: [
      Design.new(title: design_title, width: 300, height: 400),
      Design.new(title: design_title, width: 600, height: 800),
      Design.new(title: 'jersey traveling suit', width: 600, height: 800),
    ])
    get :newest, :name => 'Coco', :title => design_title
    assert_response :success
    assert_equal('Coco', assigns(:designer).name)
    assert_equal(2, assigns(:designs).size)
    assigns(:designs).each do |design|
      assert_equal(design_title, design.title)
    end
    puts @response.body
  end
end

result

Run options: --name=test_newest

# Running tests:

      params: {"name"=>"Coco", "title"=>"little black dress", "controller"=>"designs", "action"=>"newest"}
      designer: #<Designer _id: 4fb28df8e4d30bd575000004, _type: nil, name: "Coco">
      designs by title: [#<Design _id: 4fb28df8e4d30bd575000001, _type: nil, designer_id: BSON::ObjectId('4fb28df8e4d30bd575000004'), width: nil, height: nil, description: nil, title: "little black dress", tags: nil, featured: false>, #<Design _id: 4fb28df8e4d30bd575000002, _type: nil, designer_id: BSON::ObjectId('4fb28df8e4d30bd575000004'), width: nil, height: nil, description: nil, title: "little black dress", tags: nil, featured: false>]:
.

Finished tests in 0.043330s, 23.0787 tests/s, 115.3935 assertions/s.

1 tests, 5 assertions, 0 failures, 0 errors, 0 skips