Undefined save method when using dynamic finders in rake task

I have a simple rake task importing records from a CSV file and saving them into the database.

require 'csv'

namespace :import do
  task :items => :environment do

  CSV.foreach(Rails.root.to_s + '/public/data/items.csv', :headers => true) do |开发者_开发问答row|

   @item_id = row[1]

   if item_id
    i = Item.find_or_create_by_item_id(@item_id)
    i.update_attributes(
      :item_id     => @item_id,
      :category    => row[2],
      :price       => row[3],
    )
    i.save
   end

  end

 end
end

When I run it I get the following error.

rake aborted!
undefined method `save' for []:ActiveRecord::Relation

This was working fine and I have other rake tasks using dynamic finders on the same model in the same way which work fine. I can't figure out what changed or what is causing this. Any ideas would be greatly appreciated.

You have if item_id. Should that be @item_id? Also, update_attributes automatically saves the record. You don't need to call save(). Remove that line and see if that gets rid of the error.

As a side note, why do you have an attribute for Item called item_id? It would be a lot better just to use id unless you have a really good reason not to.