Different selects in one form with same name attribute?

Question

I have the following scenario:

 class Product < ActiveRecord::Base
 belongs_to :categories
 end
 class Category < ActiveRecord::Base
 has_many :products
 end

Categories table has 2 level nesting, for example. Main category is 'Men', sub-category is 'Accessories' and sub-sub-category is 'Watches'. enter image description here

Now when user creates new product he must choose category(only main category is required, but he can also chose sub and sub-sub category optional).

My idea is this: I created 3 different select boxes with same name "product[category_id]", so only the last selected value will be sent to the server through params[:product][:category_id].

<div class="col-md-2 main-category">
 <small> Main category? required </small>
 <%= f.select :category_id, 
 Category.where('category_id IS ?', nil).collect {|c| [c.name, c.id]},
 { include_blank: "Select category..." }, 
 id: 'main-category', class: 'form-control' %>
</div>
<div class="col-md-2 category-level-1">
 <small> What type? optional </small>
 <%= f.select :category_id, {}, {}, class: 'form-control' %>
</div>
<div class="col-md-2 category-level-2">
 <small> What type? optional </small>
 <%= f.select :category_id, {}, {}, class: 'form-control' %>
</div>

2nd(sub-categories) and 3rd(sub-sub-categories) are initial empty ({}, {}) and hidden through CSS(display: none) and will be populated through Ajax call.

$('#main-category, .category-level-1 > select').change(function() {
 var selectBox = this.id;
 var selectedValue = $(this).val();
 var url = '/categories/' + selectedValue + '/subcategories';
 $.get(url, function(data) { createSelect(data, selectBox); });
});
function createSelect(data, selectBox) {
 var $currentSelect = null;
 if (selectBox == 'main-category') {
 $('.category-level-1').show();
 $('.category-level-2').hide();
 $('.category-level-1 > select').find('option').remove();
 $currentSelect = $('.category-level-1 > select');
 }
 else {
 $('.category-level-2').show();
 $('.category-level-2 > select').find('option').remove();
 $currentSelect = $('.category-level-2 > select');
 }
 $currentSelect.append('<option selected disabled>Select Category...</option>');
 for(var i=0; i<data.length; i++) {
 $currentSelect.append('<option value="' + data[i].id + '">' + data[i].name +
 '</option>');
 }
}

Where Ajax call is sent to following route (categories controller)

def subcategories
 id = params[:id]
 @subcategories = Category.where('category_id = ?', id)
 render json: @subcategories 
end

So for final result i have following: enter image description here

First of all, is it normal to have different inputs in one form with same names created manually like I did in this example? For some reason, it seem like 'code-smell' to me. I'm relatively new to Rails, so I wanted to ask if I am violating some good practices with this code. Can you suggest better ways of achieving the same results?

Answer 1

These are nested selects, you can try awesome_nested_set, and use it like this:

<%= f.select :parent_id, 
 nested_set_options(Category, @category) {|i| "#{'-' * i.level} #{i.name}" } %>