Rails 4 - Devise - Put the current_user.email for the comment - ruby-on-rails-4

Question

I would like with Rails4 to assign the current_user.email to a comment.
This comment is assign to a book.
[Page book][1] [1]: http://i.stack.imgur.com/2mEoG.png
I succeed to assign the current_user.email to a comment
but when i try to change the current_user with an other account, all the email of the comments change also. And i don't want that!
How can i resolve the problem?
Here some files of my app:
CommentsController:
class CommentsController < ApplicationController
def create
#book = Book.find(params[:book_id])
#comment = #book.comments.new(comment_params)
if #comment.save
redirect_to #comment.book, notice: I18n.t('books.comment')
else
render text: 'Error!'
end
end
private
def comment_params
params.require(:comment).permit(:message)
end
end
view:
<% if comment.message != nil %>
<li><strong><%= current_user.email %></strong></li>
<p><%= comment.message %></p>
<% end %>
form_for:
<%= form_for [#book, #comment] do |f| %>
<%= f.hidden_field :book_id %>
<%= f.text_area :message, :placeholder => "Message" %>
<br />
<%= f.submit %>
<% end %>
Table Comments:
class CreateComments < ActiveRecord::Migration
def change
create_table :comments do |t|
t.text :message
t.string :username
t.integer :book_id
t.integer :reader_id
t.integer :user_id
t.timestamps
end
end
end
Table Readers:
class CreateReaders < ActiveRecord::Migration
def change
create_table :readers do |t|
t.string :name
t.string :email
t.timestamps
end
end
end
Table Books:
class CreateBooks < ActiveRecord::Migration
def change
create_table :books do |t|
t.string :title
t.string :author
t.string :synopsis
t.timestamps
end
end
end

Answer 1

Well, if you want have assigned current user to comment you can place a hidden field to save users id (make sure you have configured associations in models):
form_for:
<%= form_for [#book, #comment] do |f| %>
...
<%= f.hidden_field :user_id, value: current_user.id %>
...
<% end %>
Update comment_params in controller:
private
def comment_params
params.require(:comment).permit(:message, :user_id)
end
and then, in view:
<% if comment.message != nil %>
<li>
<strong>
<%= comment.user.email %>
</strong>
</li>
<p><%= comment.message %></p>
<% end %>
That's it. If you need use reader model instead of user - you can do it in the same way..