rails paperclip: uploaded file does not get stored

I am making my first steps with the Rails plugin 'paperclip' an therefor watched the RailsCast #134: http://railscasts.com/episodes/134-paperclip

Did everthing the same, except that I'm running rails 3.0.9 and installed paperclip (2.3.15) via adding it to the Gemfile.

Until 3:00 of the cast, everything works fine. But after reloading the show-page, I get the "missing" image instead of the uploaded image. Also, inside of the 'public' directory nothing new has been created.

Any hints?

Update: As req开发者_C百科uested here the relevant code:

Gemfile:
…
gem 'paperclip'
gem 'rails', '3.0.9'
…

config/routes.rb:
Foobar::Application.routes.draw do
  resources :books
end

app/models/book.rb:
class Book < ActiveRecord::Base
  has_attached_file :cover
  attr_accessor :cover_file_name
end

app/controllers/books_controller.rb:
# nothing changed here after scaffolding

app/views/books/_form.html.erb:
<%= form_for(@book, :html => { :multipart => true}) do |f| %>
…
<div class="field">
  <%= f.file_field :cover %>
</div>

app/views/books/show.html.erb:
…
<%= image_tag «book.cover.url %>
…

db/migrate/..._create_books.rb:
class CreateBooks < ActiveRecord::Migration
  def self.up
    create_table :books do |t|
      t.string :name

      t.timestamps
    end
  end

  def self.down
    drop_table :books
  end
end

db/migrate/..._ad_attachment_cover_to_book.rb:
class AddAttachmentCoverToBook < ActiveRecord::Migration
  def self.up
    add_column :books, :cover_file_name, :string
    add_column :books, :cover_content_type, :string
    add_column :books, :cover_file_size, :integer
    add_column :books, :cover_updated_at, :datetime
  end

  def self.down
    remove_column :books, :cover_file_name
    remove_column :books, :cover_content_type
    remove_column :books, :cover_file_size
    remove_column :books, :cover_updated_at
  end
end

I started up with "rails generate paperclip book cover" after having scaffold "book"

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I think that the attr_accessor :cover_file_name creates a conflict for the table column with the same name. Try removing that line. Can't find anything else that should cause any problems.

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People I think I already gave the solution when you appear this error is because the cover column does not have permission to enter this is solved in the controller of articles in the params_article can only manipulate the title and the body to this also adds to it To the column cover to me I stay like this

Def articulo_params params.require (: article) .permit (: title,: body,: cover)
End