How do you reference only the persisted records in an active record association

Question

In the edit method of many controllers you initialize a new object and edit existing objects

class MagazinesController < ApplicationController
   def edit         


        

Answer 1

I approach this problem differently. I do not create a new object in the controller, but instead do so directly in the form.

First, to run through your controller, why are you passing the page_id as your primary params[:id] to your Magazines controller? Looks to me that you want this:

class MagazinesController < ApplicationController
   def edit
      @magazine = Magazine.find(params[:id]).includes(:pages)
   end
end

Then, in your magazines#edit view, you'd do this:

%h4 Existing pages
- @magazine.pages.each do |page|
  %p= link_to page, page.title

= form_for @magazine do |f|
  = f.fields_for :pages, @magazine.pages.build do |builder|
    = builder.text_field :title
    # etc.

In that fields_for line, you're asking for magazine-form fields for pages, but then telling it to only render the fields for a specific, new page, which you are creating on the fly with @magazine.pages.build.

References:
fields_for
Nested Model Form Railscast (See also Part 2)