Use scope access

scope_on_create.rb

# Even when you create objects they should be properly scoped... Remember this example?

      t = Tweet.new
      t.status = "RT #{@tweet.user.name}: #{@tweet.status}"
      t.original_tweet = @tweet
      t.user = current_user
      t.save

# A simplified version of this, properly scoped might look like this:

      current_user.tweets.create(
          :status => "RT #{@tweet.user.name}: #{@tweet.status}",
          :original_tweet => @tweet
          )