Rails edit additional fields of a join table using has_many :through - ruby-on-rails

Question

I'm having almost exactly the same problem as here:
Rails has_many :through saving additional fields
However I can't figure out what's missing in my code. The basic structure is following: there are Products and they may have additional services (like cleaning or sharpening). The basic price for each service is same, however products may have different coefficients. Let's say, Product 1 may have sharpening basic price * 1.5 and Product 2 may have sharpening basic price * 2. The join table is called somewhat stupid - servization, I couldn't figure out a decent name.
products_controller.rb:
def update
#product.update!(product_params)
redirect_to #product
end
def product_params
params.require(:product).permit(
:title, :description, :advertising_text, :fancy_quote, :hot, :hotpic, :product_size_ids,
{ volume_ids: [] }, { color_ids: [] }, { addservice_ids: [] }, :category_id, :subcategory_id,
options_attributes: [:size, :weight, :price, :material, :product_id],
images_attributes: [ :image, :product_id ],
servizations_attributes: [:coefficient, :product_id, :addservice_id]
)
end
product model (i cut out the irrelevant parts) :
class Product < ActiveRecord::Base
has_many :servizations
has_many :addservices, through: :servizations
accepts_nested_attributes_for :servizations
before_destroy :ensure_not_referenced_by_any_line_item
end
additional service model:
class Addservice < ActiveRecord::Base
has_many :servizations
has_many :products, through: :servizations
end
servization model
class Servization < ActiveRecord::Base
belongs_to :product
belongs_to :addservice
end
Here is my edit.html.haml:
=form_for #product do |f|
=f.label 'Title'
=f.text_field :title
%p
=f.label 'Colors'
=collection_check_boxes(:product, :color_ids, Color.all, :id, :value )
%p
=f.label 'Additional services'
=collection_check_boxes(:product, :addservice_ids, Addservice.all, :id, :title)
=f.fields_for :servization do |s|
=s.label 'Coefficient'
=s.text_field :coefficient
%p
=f.submit class: 'btn btn-default'
I have no issues saving plain services or just the colors, however when I try to edit and save the coefficient, then I receive following error:
Processing by ProductsController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"jLN59PIOgpaIQtg2/rVYcK/xUOCFzSMLosfUhOslY9tNNhjFbh16Aa1/qT/8u7LHuhNTLGr2SB7b/BitekuDJQ==", "product"=>{"title"=>"Power MI", "color_ids"=>["1", "2", "3", ""], "addservice_ids"=>["1", ""], "servization"=>{"coefficient"=>"1.5"}}, "commit"=>"Update Product", "id"=>"7"}
Product Load (0.3ms) SELECT "products".* FROM "products" WHERE "products"."id" = $1 LIMIT 1 [["id", 7]]
Unpermitted parameter: servization
Servization structure:
Servization(id: integer, product_id: integer, addservice_id: integer, coefficient: float, created_at: datetime, updated_at: datetime)
I don't get it... my options are saved well, images too. But additional services refuse to save.
Edit 1:
I think I might be close to the solution. The problem is the correct linking in the form. This is what I came up with so far:
=form_for #product do |f|
%p
=f.label "Additional Services"
%br
-Addservice.all.each do |addservice|
=check_box_tag "product[addservice_ids][]", addservice.id, #product.addservice_ids.include?(addservice.id)
=addservice.title
=text_field_tag "product[servizations][coefficient][]", addservice.servizations.where(product_id: #product.id)[0].coefficient
%br
%p
=f.submit class: 'btn btn-default'
This is the patch request:
Parameters: {"utf8"=>"✓", "authenticity_token"=>"wD8uMSu0TxvumAWcs1V6GtAFeNgYhbEPEh8HuV8RWucBuk8At6e3jMuldJWxW5Ctxed7FPe+2hprJMuQzn+6GQ==", "product"=>{"title"=>"Флешеченка на тристапяцот гигов", "color_ids"=>["1", "2", "3", ""], "addservice_ids"=>["1", "2"], "servizations"=>{"coefficient"=>["4", "5"]}}, "commit"=>"Update Product", "id"=>"5"}
However now I'm getting again
Unpermitted parameter: servizations
Error

Answer 1

The problem is here in this line
=f.fields_for :servization do |s|
which should be
=f.fields_for :servizations do |s|
Update:
You should permit :id for update to work correctly
def product_params
params.require(:product).permit(
:title, :description, :advertising_text, :fancy_quote, :hot, :hotpic, :product_size_ids,
{ volume_ids: [] }, { color_ids: [] }, { addservice_ids: [] }, :category_id, :subcategory_id,
options_attributes: [:size, :weight, :price, :material, :product_id],
images_attributes: [ :image, :product_id ],
servizations_attributes: [:id, :coefficient, :product_id, :addservice_id]
)
end