Ransack, find record that has all related records

Question

I have a recipe model which has_many ingredients and each ingredient belongs to an item. In my advanced search form, I would like a user to select multiple ingredients and let Ransack find a recipe that contains all the ingredients selected by the user.

I tried the following searchfield:

= f.collection_select(:ingredients_item_id_in, Item.all, :id, :name, {}, {multiple: true})

But logically, this results in all recipes being shown that contain any of the selected ingredients.

changing :ingredients_item_id_in to :ingredients_item_id_in_all results in an incorrect Query since one record cannot contain multiple values of item_id.

Any ideas on creating this search parameter within Ransack, or should I create a subquery for this?

Upon request, my controller method for search:

  def search
    @q = Recipe.ransack(params[:q])
    @recipes = @q.result(distinct: true).include_related_models.published
  end

Answer 1

I recently came across similar task for my project (Rails 4.2.4 / Ruby 2.3.1).

Estate has many comforts. I need to get all estates, which include all selected comforts.

Here is how I resolved it using Ransack

In my case I have has_many :through relation.

estate.rb

class Estate < ActiveRecord::Base
  has_many :estate_comforts
  has_many :comforts, through: :estate_comforts
end

comfort.rb

class Comfort < ActiveRecord::Base
  has_many :estate_comforts
  has_many :estates, through: :estate_comforts
end

estate_comfort.rb

class EstateComfort < ActiveRecord::Base
  belongs_to :estate
  belongs_to :comfort
end

For complex queries you'll need to do search via post. For that you have to edit routes like this. And add search action to estates_controlle.rb. For more info read Ransack wiki

routes.rb

...
resources :estates
  collection do
    match 'search' => 'estates#search', via: %i[get post], as: :search
  end
end

estates_controller.rb

class EstatesController < ApplicationController
  ...

  def index
    @q = Estate.ransack(params[:q])

    @estates =
      if params[:q]&.has_key?(:estate_comforts_comfort_id_eq_any)
        # Store checked comforts
        session[:estate_comforts_comfort_id_eq_any] = params[:q][:estate_comforts_comfort_id_eq_any]

        comforts_count = params[:q][:estate_comforts_comfort_id_eq_any].count
        ids = @q.result.includes(:estate_comforts).group_by(&:id).select { |_, v| v.count == comforts_count}.keys
        Estate.where(id: ids)
      else
        @q.result(distinct: true)
      end
  end

  def search
    index
    render :index
  end
end

And finally the template portion...

estates/index.haml

= search_form_for @q, url: search_estates_path, html: { method: :post } do |f|
  # here goes the form inputs

  # Polulate checkboxes with previously checked comforts 
  - Comfort.find_each do |comfort|
    # Was checked previously?
    - checked = comfort.id.to_s.in?(session[:estate_comforts_comfort_id_eq_any].to_a)
    %div  
      %input{ name: 'q[estate_comforts_comfort_id_eq_any][]',
              type: "checkbox",
              id: "checkbox#{comfort.id}",
              value: comfort.id,
              checked: checked }
        %label{for: "checkbox#{comfort.id}"}= comfort.name

Will generate following html

<form class="estate_search" id="estate_search" action="/estates/search" accept-charset="UTF-8" method="post">
  <div>
    <input checked="" id="checkbox1" name="q[estate_comforts_comfort_id_eq_any][]" type="checkbox" value="1">
    <label for="checkbox1">Comfort Name 1</label>
  </div>
  <div>
    <input id="checkbox2" name="q[estate_comforts_comfort_id_eq_any][]" type="checkbox" value="2">
    <label for="checkbox2">Comfort Name 2</label>
  </div>
</form>