Moving response callbacks out of controller

card_creator.rb

class CardCreator < Struct.new(:listener)
  def create(iteration, attributes)
    card = iteration.cards.build(attributes)
    if card.save
      listener.created(card)
    else
      listener.create_failed(card)
    end
  end
end

card_persistence_responder.rb

class CardPersistenceResponder < SimpleDelegator
  def created(card)
    redirect_to planning_path(card.project)
  end

  def create_failed(card)
    flash.now[:alert] = 'Your card needs a title'
    render :action => 'new', locals: { card: card, title: 'New card' }
  end
end

cards_controller.rb

class CardsController < ApplicationController
  def create
    creator = CardCreator.new(CardPersistenceResponder.new(self))
    creator.create(project.backlog, card_params)
  end
end

You have to edit the views so you don't use ivars... But that's no bad thing!