How to export CSV in rails 3

class BooksController < ApplicationController
 
  # GET /books
  # GET /books.xml
  def index
   step=2
    @books = Book.paginate(:all, :page=>params[:page], :per_page=>2)
   str = ""
    datestamp = Date.today.strftime("%d%b%Y%H")
    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @books }
      format.csv do
     
        csv_data=FasterCSV.generate(str) do |csv|
          csv << ["Serial", "Name","Author Name" ,"Description", "pages","isbn", "Created At", "Modified At"]
         
         
         
           @books.each do |b|
          csv << [b.id,b.name,b.author.name,b.description,b.pages,b.isbn,b.created_at,b.updated_at]
     
        end
         end
        send_data csv_data,
    :type => 'text/csv; charset=iso-8859-1; header=present',
    :disposition => "attachment; filename=books"+datestamp+".csv"
        flash[:notice] = "Export complete!"
      end
    end
  end
 
 
  # GET /books/1
  # GET /books/1.xml
  def show
    @book = Book.find(params[:id])
    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @book }
    end
  end
 
  # GET /books/new
  # GET /books/new.xml
  def new
    @book = Book.new
   
    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @book }
    end
  end
 
  # GET /books/1/edit
  def edit
    @book = Book.find(params[:id])
  end
 
  # POST /books
  # POST /books.xml
  def create
    @book = Book.new(params[:book])
   
    respond_to do |format|
      if @book.save
        flash[:notice] = 'Book was successfully created.'
        format.html { redirect_to(@book) }
        format.xml  { render :xml => @book, :status => :created, :location => @book }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @book.errors, :status => :unprocessable_entity }
      end
    end
  end
 
  # PUT /books/1
  # PUT /books/1.xml
  def update
    @book = Book.find(params[:id])
   
    respond_to do |format|
      if @book.update_attributes(params[:book])
        flash[:notice] = 'Book was successfully updated.'
        format.html { redirect_to(@book) }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @book.errors, :status => :unprocessable_entity }
      end
    end
  end
 
  # DELETE /books/1
  # DELETE /books/1.xml
  def destroy
    @book = Book.find(params[:id])
    @book.destroy
   
    respond_to do |format|
      format.html { redirect_to(books_url) }
      format.xml  { head :ok }
    end
  end
end