Pass another data than the id in the URL - ruby-on-rails

Question

I'm currently creating a website that would allow a visitor to read a magazine online. I created a scaffold for the magazine itself, and another one for the pages, which belongs to the magazine. This way, I can create a multi upload for the pages while creating the magazine, and everything gets uploaded in the same time.
When I nest the pages resources inside the magazine's resources, as following:
resources :magazines do
resources :pages
end
I get "domain.com/magazines/<slug>/pages/id"
However, I had some issues with the id, because it can't be used to count the pages (since the id never goes back to 1), so I created a function inside the controller that would count the pages for me, and save each pages with a "page_number" value.
My question is the following: how, instead of the id, can I kindly ask my router to use the :page_number ?
I tried to create a custom route, which looked like this
resources :magazines do
get '/:page_number' => 'pages#show', as: :custom_page
end
But for an unknown reason, Rails tells me that my custom route simply doesn't exist, even though it exists when I type rake routes
Thank you in advance
Edit
Here is my magazine_controller.rb
class MagazinesController < ApplicationController
before_action :authenticate_user!, only: [:edit, :update, :destroy]
before_action :set_magazine, only: [:show, :edit, :update, :destroy]
def index
#magazines = Magazine.all
end
def show
end
def new
#magazine = Magazine.new
end
def edit
end
def create
#magazine = Magazine.new(magazine_params)
if #magazine.save
if params[:images]
(params[:image] || []).each_with_index do |image, index|
#magazine.pages.create(image: image, page_number: index + 1)
end
redirect_to #magazine, notice: 'Magazine was successfully created.'
else
render :new
end
end
end
def update
if #magazine.update(magazine_params)
if params[:images]
params[:images].each { |image|
#magazine.pages.create(image: image)
}
end
redirect_to #magazine, notice: 'Magazine was successfully updated.'
else
render :edit
end
end
def destroy
#magazine.destroy
redirect_to magazines_url, notice: 'Magazine was successfully destroyed.'
end
private
def set_magazine
#magazine = Magazine.friendly.find(params[:id])
end
def magazine_params
params.require(:magazine).permit(:titre, :apercu)
end
end
and here is page_controller.rb
class PagesController < ApplicationController
before_action :authenticate_user!, only: [:edit, :update, :destroy]
before_action :set_page, only: [:show, :edit, :update, :destroy]
def index
#pages = Page.all
end
def show
end
def new
#page = Page.new
end
def edit
end
def create
#page = Page.new(page_params)
if #page.save
redirect_to #page, notice: 'Page was successfully created.'
else
render :new
end
end
def update
if #page.update(page_params)
redirect_to #page, notice: 'Page was successfully updated.'
else
render :edit
end
end
def destroy
#page.destroy
redirect_to :back, notice: 'Page was successfully destroyed.'
end
private
def set_page
#page = Page.find(params[:id])
end
def page_params
params.require(:page).permit(:titre, :apercu)
end
end
Edit 2
Here is the output from development.log when trying to reach the page
Started GET "/magazines/magazine-54/pages/11" for 127.0.0.1 at 2016-12-12 11:04:45 +0100
Processing by PagesController#show as HTML
Parameters: {"magazine_id"=>"magazine-54", "id"=>"11"}
Completed 500 Internal Server Error in 2ms (ActiveRecord: 0.0ms)
NoMethodError (undefined method `pages' for nil:NilClass):
app/controllers/pages_controller.rb:49:in `set_page'
Rendering /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout
Rendering /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb
Rendered /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb (2.4ms)
Rendering /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb
Rendered /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (1.2ms)
Rendering /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb
Rendered /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (0.7ms)
Rendered /var/lib/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (13.8ms)

Answer 1

With these routes
resources :magazines do
resources :pages
end
you should be able to update PagesController and add/update following methods:
def magazine
#magazine = Magazine.find(params[:magazine_id])
end
def page
#page = #magazine.pages.find_by(page_number: params[:id])
end
to make it work you should have page_number column in Page model and has_many :pages association in Magazine model