Simple breadcrumbs for Rails

application.html.erb

<!-- Simple breadcrumbs for Rails -->
<!-- Example output -->

<!-- This example uses the Twitter Bootstrap classes for breadcrumbs -->
<!-- http://twitter.github.com/bootstrap/components.html#breadcrumbs -->

<% if breadcrumbs %>
  <ul class="breadcrumb">
    <% breadcrumbs.each do |crumb| %>
      <li>

        <%# You could even turn these next 5 lines into a helper,
            `link_or_else_title(crumb[:title], crumb[:link])` or something. %>

        <% if crumb[:link].present? %>
          <%= link_to crumb[:title], crumb[:link] %>
        <% else %>
          <%= crumb[:title] %>
        <% end %>

        <% unless crumb == breadcrumbs.last %>
          <span class="divider">/</span>
        <% end %>
      </li>
    <% end %>
  </ul>
<% end %>

application_controller.rb

# Simple breadcrumbs for Rails
# A very easy and elegant way to add breadcrumbs
# to your Rails application.

# This gist is adapted from my usage of it so I apologize if there are mistakes.

class ApplicationController < ActionController::Base
  # This before_filter adds a root node to the breadcrumbs for
  # every request. Only necessary if you want a "Home" link, for
  # example.
  before_filter :root_breadcrumb
  
  def root_breadcrumb
    breadcrumb "Home", root_path
  end

  def breadcrumb(*args)
    @breadcrumbs ||= []

    # Grab pairs from the arguments and convert to hash
    pairs = args.each_slice(2).map { |pair| { title: pair[0], link: pair[1] } }

    # Push each hash into @breadcrumbs
    pairs.each { |pair| @breadcrumbs.push(pair) }
  end

  # Setup a helper method for reading the breadcrumbs.
  # Not necessary, but makes the views look a little cleaner.
  # Replace `breadcrumbs` with `@breadcrumbs` in the views if
  # you don't use this helper method.
  attr_reader :breadcrumbs  
  helper_method :breadcrumbs
end

blog_entries_controller.rb

# Simple breadcrumbs for Rails
# Example usage in your normal controllers.

class BlogEntriesController < ApplicationController
  before_filter :get_blog_entry, only: [:show, :edit, :update, :destroy]
  before_filter :resource_breadcrumb

  def index
    # Breadcrumb already created by before_filter
  end

  def new
    # A link is not required. Leave it off if you don't need it.
    breadcrumb "New Blog Entry"
  end

  def show
    breadcrumb @blog_entry.title, blog_entry_path(@blog_entry)
  end

  def create
    # You can put a breadcrumb here but it will only be seen
    # if there is an error on the form.
    # You can append more than one breadcrumb at a time, but
    # remember it's grouped every two, so if you don't want a
    # link on one, pass "nil" in between.

    breadcrumb "New Blog Entry", nil, "Error!"
  end

  # `update` & `destroy` are similar to `create`

  protected
    def get_blog_entry
      if !@blog_entry = BlogEntry.find_by_id(params[:id])
        redirect_to blog_entries_path and return false
      end
    end 

    def resource_breadcrumb
      breadcrumb "Blog Entries", blog_entries_path
    end
end

breadcrumb_spec.rb

# Simple breadcrumbs for Rails
# Basic specs

describe ApplicationController do

  describe "breadcrumbs" do
    it "returns @breadcrumbs" do
      controller.instance_variable_set(:@breadcrumbs, true)
      controller.breadcrumbs.should eq true
    end
  end

  describe "breadcrumb" do
    it "pushes the arguments, grouped in pairs as a hash, into @breadcrumbs" do
      controller.breadcrumb("Home", "/home", "New")
      controller.breadcrumbs.should eq [{title: "Home", link: "/home"}, {title: "New", link: nil}]
    end
    
    it "appends to @breadcrumbs if the variable already exists" do
      controller.instance_variable_set(:@breadcrumbs, [{title: "Home", link: "/home"}])
      controller.breadcrumb("New", nil, "Blogs", "/blogs")
      controller.breadcrumbs.should eq [{title: "Home", link: "/home"}, {title: "New", link: nil}, {title: "Blogs", link: "/blogs"}]
    end
  end
end