Loaf manages and displays breadcrumb trails in your Rails application.

• Use controllers and/or views to specify breadcrumb trails
• Specify urls using Rails conventions
• No markup assumptions for breadcrumbs trails rendering
• Use locales file for breadcrumb names
• Tested with Rails >= 3.2 and Ruby >= 2.0.0

Add this line to your application's Gemfile:

gem "loaf"

And then execute:

$ bundle

Or install it yourself as:

gem install loaf

Then run the generator:

rails generate loaf:install

• 1. Usage
• 2. API
  • 2.1 breadcrumb
    • 2.1.1 controller
    • 2.1.2 view
    • 2.1.3 :match
  • 2.2 breadcrumb_trail
• 3. Configuration
• 4. Translation

Loaf allows you to add breadcrumbs in controllers and views.

In order to add breadcrumbs in controller use breadcrumb method (see 2.1).

class Blog::CategoriesController < ApplicationController

  breadcrumb "Article Categories", :blog_categories_path, only: [:show]

  def show
    breadcrumb @category.title, blog_category_path(@category)
  end
end

Then in your view render the breadcrumbs trail using breadcrumb_trail

Creation of breadcrumb in Rails is achieved by the breadcrumb helper.

The breadcrumb method takes at minimum two arguments: the first is a name for the crumb that will be displayed and the second is a url that the name points to. The url parameter uses the familiar Rails conventions.

When using path variable blog_categories_path:

breadcrumb "Categories", blog_categories_path

When using an instance @category:

breadcrumb @category.title, blog_category_path(@category)

You can also use set of objects:

breadcrumb @category.title, [:blog, @category]

You can specify segments of the url:

breadcrumb @category.title, {controller: "categories", action: "show", id: @category.id}

Breadcrumbs are inherited, so if you set a breadcrumb in ApplicationController, it will be inserted as a first element inside every breadcrumb trail. It is customary to set root breadcrumb like so:

class ApplicationController < ActionController::Base
  breadcrumb "Home", :root_path
end

Outside of controller actions the breadcrumb helper behaviour is similar to filters/actions and as such you can limit breadcrumb scope with familiar options :only, :except. Any breadcrumb specified inside actions creates another level in breadcrumbs trail.

class ArticlesController < ApplicationController
  breadcrumb "All Articles", :articles_path, only: [:new, :create]
end

Each time you call the breadcrumb helper, a new element is added to a breadcrumb trial stack:

class ArticlesController < ApplicationController
  breadcrumb "Home", :root_path
  breadcrumb "All Articles", :articles_path

  def show
    breadcrumb "Article One", article_path(:one)
    breadcrumb "Article Two", article_path(:two)
  end
end

Loaf allows you to call controller instance methods inside the breadcrumb helper outside of any action. This is useful if your breadcrumb has parameterized behaviour. For example, to dynamically evaluate parameters for breadcrumb title do:

class CommentsController < ApplicationController
  breadcrumb -> { find_article(params[:post_id]).title }, :articles_path
end

Also, to dynamically evaluate parameters inside the url argument do:

class CommentsController < ApplicationController
  breadcrumb "All Comments", -> { post_comments_path(params[:post_id]) }
end

You may wish to define breadcrumbs over a collection. This is easy within views, and controller actions (just loop your collection), but if you want to do this in the controller class you can use the before_action approach:

before_action do
  ancestors.each do |ancestor|
    breadcrumb ancestor.name, [:admin, ancestor]
  end
end

Assume ancestors method is defined inside the controller.

Loaf adds breadcrumb helper also to the views. Together with controller breadcrumbs, the view breadcrumbs are appended as the last in breadcrumb trail. For instance, to specify view breadcrumb do:

<% breadcrumb @category.title, blog_category_path(@category) %>

Loaf allows you to define matching conditions in order to make a breadcrumb current with the :match option.

The :match key accepts the following values:

• :inclusive - the default value, which matches nested paths
• :exact - matches only the exact same path
• :exclusive - matches only direct path and its query parameters if present
• /regex/ - matches based on regular expression
• {foo: bar} - match based on query parameters

For example, to force a breadcrumb to be the current regardless do:

breadcrumb "New Post", new_post_path, match: :exact

To make a breadcrumb current based on the query parameters do:

breadcrumb "Posts", posts_path(order: :desc), match: {order: :desc}

In order to display breadcrumbs use the breadcrumb_trail view helper. It accepts optional argument of configuration options and can be used in two ways.

One way, given a block it will yield all the breadcrumbs in order of definition:

breadcrumb_trail do |crumb|
  ...
end

The yielded parameter is an instance of Loaf::Crumb object with the following methods:

crumb.name     # => the name as string
crumb.path     # => the path as string
crumb.url      # => alias for path
crumb.current? # => true or false

For example, you can add the following semantic markup to show breadcrumbs using the breadcrumb_trail helper like so:

<nav aria-label="breadcrumb">
  <ol class="breadcrumbs">
    <% breadcrumb_trail do |crumb| %>
      <li class="<%= crumb.current? ? "current" : "" %>">
        <%= link_to crumb.name, crumb.url, (crumb.current? ? {"aria-current" => "page"} : {}) %>
        <% unless crumb.current? %><span>::</span><% end %>
      </li>
    <% end %>
  </ol>
</nav>

For Bootstrap 4:

<% #erb %>
<nav aria-label="breadcrumb">
  <ol class="breadcrumb">
    <% breadcrumb_trail do |crumb| %>
      <li class="breadcrumb-item <%= crumb.current? ? "active" : "" %>">
        <%= link_to_unless crumb.current?, crumb.name, crumb.url, (crumb.current? ? {"aria-current" => "page"} : {}) %>
      </li>
    <% end %>
  </ol>
</nav>

And, if you are using HAML do:

  - # haml
  %ol.breadcrumb
    - breadcrumb_trail do |crumb|
      %li.breadcrumb-item{class: crumb.current? ? "active" : "" }
        = link_to_unless crumb.current?, crumb.name, crumb.url, (crumb.current? ? {"aria-current" => "page"} : {})

Usually best practice is to put such snippet inside its own _breadcrumbs.html.erb partial.

The second way is to use the breadcrumb_trail without passing a block. In this case, the helper will return an enumerator that you can use to, for example, access an array of names pushed into the breadcrumb trail in order of addition. This can be handy for generating page titles from breadcrumb data.

For example, you can define a breadcrumbs_to_title method in ApplicationHelper like so:

module ApplicationHelper
  def breadcrumbs_to_title
    breadcrumb_trail.map(&:name).join(">")
  end
end

Use whichever of the two ways is more convenient given your application structure and needs.

There is a small set of custom opinionated defaults. The following options are valid parameters:

:match # set match type, default :inclusive (see [:match](#213-match) for more details)

You can override them in your views by passing them to the view breadcrumb helper

<% breadcrumb_trail(match: :exclusive) do |name, url, styles| %>
  ..
<% end %>

or by configuring an option in config/initializers/loaf.rb:

Loaf.configure do |config|
  config.match = :exclusive
end

You can use locales files for breadcrumbs' titles. Loaf assumes that all breadcrumb names are scoped inside breadcrumbs namespace inside loaf scope. However, this can be easily changed by passing scope: 'new_scope_name' configuration option.

en:
  loaf:
    breadcrumbs:
      name: 'my-breadcrumb-name'

Therefore, in your controller/view you would do:

class Blog::CategoriesController < ApplicationController
  breadcrumb 'blog.categories', :blog_categories_path
end

And corresponding entry in locale would be:

en:
  loaf:
    breadcrumbs:
      blog:
        categories: 'Article Categories'

Questions or problems? Please post them on the issue tracker. You can contribute changes by forking the project and submitting a pull request. You can ensure the tests are passing by running bundle and rake.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Loaf project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

Copyright (c) 2011 Piotr Murach. See LICENSE.txt for further details.