Rails Multiple checkboxes with associated Text fields - ruby-on-rails

Question

I'm trying to create a Product form that has multiple sizes and prices for each of those sizes.
They way I have it modelled is a has_many :through relationship.
The associative table contains an extra field for price such that it will now hold the product_id, size_id, and price.
I'm not sure how I should go about creating my form or how Rails expects this to look. Any help would be much appreciated.
My Product is Cake :)
class Cake < ApplicationRecord
belongs_to :cake_type
has_many :cake_details
has_many :sizes, through: :cake_details
end
Size model
class Size < ApplicationRecord
has_many :cake_details
has_many :cakes, through: :cake_details
end
CakeDetail model
class CakeDetail < ApplicationRecord
belongs_to :cake
belongs_to :size
end
my migration
class CreateCakeDetails < ActiveRecord::Migration[5.1]
def change
create_table :cake_details do |t|
t.references :cake, foreign_key: true
t.references :size, foreign_key: true
t.decimal :price, :precision => 10, :scale => 2
t.timestamps
end
end
end
The only thing I'm stuck on is associating the form with the model.
i.e. for every size I want to have a text box with price associated with it.
This is currently how I'm approaching it but I have no idea how rails expects the id's of the text box to look or how I should structure this.
This is currently what I'm experimenting with in my form
<%= collection_check_boxes(:cake, :size_ids, Size.all, :id, :name) do |b| %>
<tr>
<td>
<%= b.label %>
</td>
<td>
<%= b.check_box %>
</td>
<td>
<%= form.text_field :cake_detail, id: b.label %>
</td>
</tr>
<% end %>

Answer 1

The way you define your business logic is normal
- A product has multiple sizes
- Each size has a price
The only thing I believe that it leads you to the problem is you are trying to create everything at the same time. Even Rails has nested_attributes which might solve your problem, but let's think once again.
Generally, Size records are fixed and was created beforehand. So that you don't have to create it at the same time with creating a Product.
Once you deal with this idea, your problem becomes much easier:
You had a list of Size: M, L, XL, XXL ... that was created beforehand
( You may create them via db/seeds.rb )
You want to create Product along ProductDetail with prices,
and link the ProductDetail with Size
Now you can use Rails's nested_attributes for the relation Product -> ProductDetail
Your model
# app/models/cake.rb
class Cake < ApplicationRecord
belongs_to :cake_type
has_many :cake_details
has_many :sizes, through: :cake_details
attr_accessor :is_enable
accepts_nested_attributes_for :cake_details, reject_if: :is_not_good_detail?
private
def is_not_good_detail?(attributed)
return true if attributed[:is_enable].to_i != 1
# Check if CakeDetail is good or not
end
end
Your controller
# app/controllers/cakes_controller.rb
class CakesController < ApplicationController
def new
#cake = Cake.new
# Build `cake_details`, so that you can render them at view
Size.each do |size|
#cake.cake_details.build(size_id: size.id, price: 0)
end
end
def create
# Create your Cake + CakeDetail
end
private
def cake_params
# permit your params here
end
end
Your view
# app/views/cakes/_form.html.erb
<%= form_for #cake do |f| %>
<%= f.fields_for :cakes_detail do |field| %>
<%= field.check_box :is_enable %>
<%= field.hidden_field :size_id %>
<%= field.text_field :price %>
<% end>
<% end %>
My code is completely not tested, and you still have a lot of things to do, but it should be the right way to solve your problem, tho.
You can consider the checklist to make it done:
Display name of size. Ex: XL, XXL
Permit the right params
Reject the invalid CakeDetail attribute set.
Avoid duplicate of size for a product when updating
<< Update >>>
Since the check_box only produces 0 and 1 value, so using it for size_id is incorrect. We can solve it by:
add an attr_accessor (ex: is_enable) for CakeDetail and use it for the check_box
size_id become a hidden field
Reject attributes if is_enable != 1
You can found here a working example yeuem1vannam/product-size