Question

I have a users model and a book model. Users can read books (as a reader) which creates an entry in the Readings model:

id | reader_id | book_id

Users also have a list of books that they have read. These are stored in the Red (I use Red because the present and past tense of the word ‘read’ are the same) model which looks the same as the Reading model above.

Now when a user is reading a book, I would like to display a button which represents finishing the book.

The finish action is in the ReadingsController and looks like this:

def finish
  @book = current_user.readings.find(params[:id]).book
  current_user.stop_reading!(@book)
  current_user.make_red! @book

  redirect_to :back
end

As you can probably tell, this takes in the id of a record in the readings table, destroys it and makes a new record in the table for recording books red.

The form helper for the “Finish Reading” button currently looks like this:

<%= form_for :reading, current_user.readings.find_by_book_id(book.id), :url => { :controller => :readings, :action => "finish" }, :method => :delete do |f| %>
  <div class="actions"><%= f.submit button_text %></div>
<% end %>

But for some reason this renders a form with the wrong id because “9781440506604” is not the id of a record in the readings table, it’s the id of a record in the books table (the ISBN-13 of a book to be precise).

<form accept-charset="UTF-8" action="/readings/9781440506604/finish" method="post">
</form>

What is it I’m doing wrong?

EDIT to add reading.rb

class Reading < ActiveRecord::Base
  attr_accessible :book_id

  # one person reading a new book may cause feed_item creations in multiple users feeds
  has_many :feed_items, :as => :event
  has_many :comments, :as => :parent, :dependent => :destroy

  scope :from_users_followed_by, lambda { |user| followed_by(user) }

  # need to pass the class name here because there is no Reader model
  belongs_to :reader, :class_name => "User"
  belongs_to :book

  validates :reader_id, :presence => true
  validates :book_id, :presence => true

  def self.followed_by(user)
    ...
  end
end

# and user.rb
class User < ActiveRecord::Base
attr_accessible :name, :email, :password, :password_confirmation, :avatar, :remember_me, :avatar_url
has_many :readings, :dependent => :destroy,
                      :foreign_key => "reader_id"
  has_many :reads, :through => :readings, :source => :book
  has_many :reds, :foreign_key => "reader_id",
                  :dependent => :destroy
  has_many :red, :through => :reds, :source => :book

  def reading? book
    self.readings.find_by_book_id(book)
  end

  def read! book
    self.readings.create!(:book_id => book.id)
  end

  def stop_reading! book
    self.readings.find_by_book_id(book).destroy
  end

  def red? book
    self.reds.find_by_book_id(book)
  end

  def make_red! book
    unless red? book
      self.reds.create!(:book_id => book.id)
    end
  end
end

By the way I tried making a user who is reading book 1 and doing user.readings.find_by_book_id(1) in the console and it returns a record from the readings table.

as requested

# routes.rb
resources :readings, :only => [:create, :destroy, :show] do
  member do
    post :create_comment
    delete :finish
  end
end

Answer 1

Looks like you have got to_param method in your Reading model

try to call id clearly:

current_user.readings.find_by_book_id(book.id).id

UPD

1. remove :only => [:create, :destroy, :show] from your routes
2. use this <%= form_for :reading, current_user.readings.find_by_book_id(book.id), :url => { :controller => :readings, :action => "finish", :id => current_user.readings.find_by_book_id(book.id).id }, :html => {:method => :delete} do |f| %>