在Rails中使用合并范围进行过滤

Question

I'm trying to create a records filtering system using ActiveRecord scopes but i am stuck at the point where you have two filters of the same model. I am trying to filter products with brand_id: 1 and brand_id:2

My Product model with the brand scope defined looks like this:

class Product < ActiveRecord::Base
  belongs_to :brand

  scope :brand, lambda{|brand| where('brand_id = ?', brand )}
end

I am trying to filter the products on my categories/show view and the CategoriesController looks like this:

class CategoriesController < ApplicationController
  has_scope :brand

  def show
    @category = Category.find(params[:id])
    @products_by_category = apply_scopes(Product).where(category_id: @category).load
    @brands = @category.brands
  end
end

The categories/show view looks like this:

<% @products_by_category.each do |product| %>
  <h2><%= product.name %></h2>
<% end %>

i am using this form to do the filtering:

<%= form_tag @category_path, method: get do %>
  <% @brands.each do |brand| %>
    <span class="filter_name"><%= brand.name%>:</span>
    <span> <%= check_box_tag :brand, brand.id, false,
                                     class: 'filter_check_box' %> </span>

   <% end %>
  <%=submit_tag 'filter'%>
<% end %>

The problem is when i select more than one brand in the check_boxes, it filters the products with only the first parameter;

for example if i filter with brands with :id 1 and :id 2 and submits the form, it the request url looks like this: http://localhost:3000/categories/1?&brand=1&brand=4 and the queried array is only filtered with brand=1 . I would like the results to be filtered by both parameters. Is the resulting url even correct or should it be: http://localhost:3000/categories/1?&brand=1,4 ?

Answer 1

All of the filter inputs you are submitting have the same parameters key, brand . So, the parameters hash can only have one value for that key.

You want to use a check_box_tag instead for 'brand_ids[]' :

<%= check_box_tag 'brand_ids[]', brand.id, false, class: 'filter_check_box' %>

Finally, and this is important , you cannot send an array to the parameters via a GET action. You will need to use a POST. As the second link below notes, this is a limitation of HTTP, not Rails.

See also:

• Select checkbox pass array in ruby on rails
• Passing array of parameters through get in rails

Aside

I would humbly recommend you refer to variables with more consistent names, for ease of readability and maintenance of code. If you're using a brand_id, as in that Product scope, call it a brand_id, not a brand.