Problem with Ruby on Rails

[Pirate Ninja]

Okay im gonna make this Short.

Error:

You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.save

D:/Rails/rails_apps/LearningRails/app/controllers/book_controller.rb:14:in `create'

Request:

{"commit"=>"Create",
 "authenticity_token"=>"qQJ0RNgsZsmk+ZM0ICs9BPeFX79usVIh93lbLDIYlok=",
 "book"=>{"title"=>"sadsad",
 "price"=>"34",
 "description"=>"sadfadsfdsfdsaf",
 "subject_id"=>"1"}}

Controller:

def create
   	@book == Book.new(params[:book])
   	if @book.save
   		 redirect_to :action => 'list'
   	else
   		@subjects = Subject.find(:all)
   		render :action => 'new'
   	end
   end

View:

<h1>Add new book</h1>
<% form_tag :action => 'create'  do %>
<p><label for="book_title">Title</label>:
<%= text_field 'book', 'title' %></p>
<p><label for="book_price">Price</label>:
<%= text_field 'book', 'price' %></p>
<p><label for="book_subject">Subject</label>:
<%= collection_select(:book,:subject_id,@subjects,:id,:name) %></p>
<p><label for="book_description">Description</label><br/>
<%= text_area 'book', 'description' %></p>
<%= submit_tag "Create" %>
<% end  %>
<%= link_to 'Back', {:action => 'list'} %>

Thanks in advance.

[editline]06:10PM[/editline]

Fixed it.
Accidentally typed:
@book == Book.new(params[:book])