A helper method for creating breadcrumbs based on Models. The output partial adds bootstrap dropdown functionality and generally the bootstrap breadcrumbs view.

_breadcrumbs.html.haml

%ul.breadcrumb
  - breadcrumbs.each do |breadcrumb_item|
    %li{:class => breadcrumb_item[:classes].join(' ')}
      - if breadcrumb_item[:collection] && breadcrumb_item[:collection].size > 1 #Elements with dropdowns
        %a.dropdown-toggle{'data-toggle' => 'dropdown', :href => '#'}
          = breadcrumb_item[:caption]
          %span.caret
        %ul.dropdown-menu
          - breadcrumb_item[:collection].shift if breadcrumb_item[:active]
          - breadcrumb_item[:collection].each do |bi|
            = bi[:divider] ? navigation_divider : navigation_item(bi[:caption], bi[:url], :active => false)
      - else #Elements without dropdowns
        - if breadcrumb_item[:function]
          = link_to_function breadcrumb_item[:caption], breadcrumb_item[:function], breadcrumb_item[:options]
        - elsif breadcrumb_item[:url]
          - if breadcrumb_item[:remote]
            = link_to_remote(breadcrumb_item[:caption], :url => breadcrumb_item[:url], :html => breadcrumb_item[:options])
          - else
            = link_to breadcrumb_item[:caption], breadcrumb_item[:url], breadcrumb_item[:options]
        - else
          = breadcrumb_item[:caption]
      - unless breadcrumb_item[:active]
        %span.divider= '/'

breadcrumbs_helper.rb

# Generates a breadcrumbs structure based on model classes and records
  # Example: model_breadcrumbs(Property, my_property)
  #          => "Properties » My Property Name"
  # Element types can be:
  #   - Model Classes which will be localized and pluralized
  #   - Records: If the record has a "name" attribute, it will be used.
  #              Otherwise, the Record class and ID are used
  #   - Arrays: Are converted to a collection of their parsed contents, e.g.
  #             for dropdown menus.
  #   - Hash: has to contain the keys :caption and :url and will be converted
  #           to a link_to. Can use the key :options for additional html options
  #   - everything else will just be used for output.
  #----------------------------------------------------------------------------
  def model_breadcrumbs(*elements)
    namespace = params[:controller].split('/').size > 1 ? params[:controller].split('/').first : nil
    options = {:record_links => true, :model_links => true, :namespace    => namespace }
    if elements.last.is_a?(Hash)
      options.merge!(elements.pop)
    end

    render :partial => 'breadcrumbs', :object => (elements.map {|e| breadcrumb_item(e, elements, options)})
  end

private

def breadcrumb_item(element, elements, options)
    klass = element.class
    klass = ActiveRecord::Base if klass < ActiveRecord::Base

    item = {}
    item[:active]  = element == elements.last
    item[:classes] = item[:active] ? ['active'] : []

    #We have to compare strings here, it seems to be a "feature" of case
    #that "when Class" is true for all elements which are classes...
    case klass.to_s
      when 'Array'
        item[:collection] = element.map {|e| breadcrumb_item(e, elements, options)}
        item[:caption]    = item[:collection].first[:caption]
        item[:classes]    << 'dropdown'
      when 'ActiveRecord::Base'
        item[:caption] = element.respond_to?('breadcrumb_caption') ? element.breadcrumb_caption :
                         element.class.human_name << ' #' << element.id
        if options[:record_links] && element != elements.last
          item[:url] = [options[:namespace], element].compact
        end
      when 'Class'
        item[:caption] = element.respond_to?('breadcrumb_caption') ? element.breadcrumb_caption :
                         element.human_name(:count => 2)
        if options[:model_links]
          item[:url] = [options[:namespace], element.to_s.downcase.pluralize].compact
        end
      when 'Hash'
        element.each do |k,v|
          item[k] = v
        end
      else
        item[:caption] = element
        item[:divider] = true if element.nil?
    end

    item
  end