(TL;DR) Gretel is a Ruby on Rails plugin that makes it easy yet flexible to create breadcrumbs. It is based around the idea that breadcrumbs are a concern of the view, so you define a set of breadcrumbs in config/breadcrumbs.rb (or multiple files; see below) and specify in the view which breadcrumb to use. Gretel also supports semantic breadcrumbs (those used in Google results).

Have fun! And please do write, if you (dis)like it – [email protected].

New in version 3.0

• Breadcrumbs can now be rendered in different styles like ul- and ol lists, and for use with the Twitter Bootstrap framework. See the :style option below for more info.
• Defining breadcrumbs using Gretel::Crumbs.layout do ... end in an initializer has been removed. See below for details on how to upgrade.
• The :show_root_alone option is now called :display_single_fragment and can be used to hide the breadcrumbs when there is only one link, also if it is not the root breadcrumb. The old :show_root_alone option is still supported until Gretel version 4.0 and will show a deprecation warning when it's used.
• Links yielded from <%= breadcrumbs do |links| %> now have a current? helper that returns true if the link is the last in the trail.
• New view helper: parent_breadcrumb returns the parent breadcrumb link (with #key, #text, and #url). This can for example be used to create a dynamic back link. You can supply options like :autoroot etc. If you supply a block, it will yield the parent breadcrumb if it is present.
• Breadcrumbs can now be inferred if you pass in an instance of an object that responds to model_name (like an ActiveRecord model instance). E.g. breadcrumb @product is short for breadcrumb :product, @product.

I hope you find these changes as useful as I did – if you have more suggestions, please create an Issue or Pull Request.

See below for more info or the changelog for less significant changes.

Installation

In your Gemfile:

gem "gretel"

And run:

$ bundle install

Example

Start by generating breadcrumbs configuration file:

$ rails generate gretel:install

Then, in config/breadcrumbs.rb:

# Root crumb
crumb :root do
  link "Home", root_path
end

# Issue list
crumb :issues do
  link "All issues", issues_path
end

# Issue
crumb :issue do |issue|
  link issue.title, issue
  parent :issues
end

At the top of app/views/issues/show.html.erb, set the current breadcrumb (assuming you have loaded @issue with an issue):

<% breadcrumb :issue, @issue %>

Then, in app/views/layouts/application.html.erb:

<%= breadcrumbs pretext: "You are here: ",
                separator: " &rsaquo; " %>

This will generate the following HTML (indented for readability):

<div class="breadcrumbs">
  You are here:
  <a href="/">Home</a> &rsaquo;
  <a href="/issues">All issues</a> &rsaquo;
  <span class="current">My Issue</span>
</div>

Options

You can pass options to <%= breadcrumbs %>, e.g. <%= breadcrumbs pretext: "You are here: " %>:

Option	Description	Default
:style	How to render the breadcrumbs. Can be :default, :ol, :ul, or :bootstrap. See below for more info.	:default
:pretext	Text to be rendered before breadcrumb, e.g. "You are here: ".	None
:posttext	Text to be appended after breadcrumb, e.g. "Text after breacrumb",	None
:separator	Separator between links, e.g. " › ".	" › "
:autoroot	Whether it should automatically link to the :root crumb if no parent is given.	True
:display_single_fragment	Whether it should display the breadcrumb if it includes only one link.	False
:link_current	Whether the current crumb should be linked to.	False
:semantic	Whether it should generate semantic breadcrumbs.	False
:id	ID for the breadcrumbs container.	None
:class	CSS class for the breadcrumbs container.	"breadcrumbs"
:current_class	CSS class for the current link or span.	"current"
:container_tag	Tag type that contains the breadcrumbs.	:div
:fragment_tag	Tag type to contain each breadcrumb fragment/link.	None

Styles

These are the styles you can use with breadcrumbs style: :xx.

Style	Description
:default	Renders each link by itself with › as the seperator.
:ol	Renders the links in <li> elements contained in an outer <ol>.
:ul	Renders the links in <li> elements contained in an outer <ul>.
:bootstrap	Renders the links for use in Twitter Bootstrap.
:foundation5	Renders the links for use in Foundation 5.

Or you can build the breadcrumbs manually for full customization; see below.

If you add other widely used styles, please submit a Pull Request so others can use them too.

More examples

In config/breadcrumbs.rb:

# Root crumb
crumb :root do
  link "Home", root_path
end

# Regular crumb
crumb :projects do
  link "Projects", projects_path
end

# Parent crumbs
crumb :project_issues do |project|
  link "Issues", project_issues_path(project)
  parent :project, project
end

# Child 
crumb :issue do |issue|
  link issue.name, issue_path(issue)
  parent :project_issues, issue.project
end

# Recursive parent categories
crumb :category do |category|
  link category.name, category
  if category.parent
    parent :category, category.parent
  else
    parent :categories
  end
end

# Product crumb with recursive parent categories (as defined above)
crumb :product do |product|
  link product.name, product
  parent :category, product.category
end

# Crumb with multiple links
crumb :test do
  link "One", one_path
  link "Two", two_path
  parent :about
end

# Example of using params to alter the parent, e.g. to
# match the user's actual navigation path
# URL: /products/123?q=my+search
crumb :search do |keyword|
  link "Search for #{keyword}", search_path(q: keyword)
end

crumb :product do |product|
  if keyword = params[:q].presence
    parent :search, keyword
  else # default
    parent :category, product.category
  end
end

# Multiple arguments
crumb :multiple_test do |a, b, c|
  link "Test #{a}, #{b}, #{c}", test_path
  parent :other_test, 3, 4, 5
end

# Breadcrumb without link URL; will not generate a link
crumb :without_link do
  link "Breadcrumb without link"
end

# Breadcrumb using view helper
module UsersHelper
  def user_name_for(user)
    user.name
  end
end

crumb :user do |user|
  link user_name_for(user), user
end

Building the breadcrumbs manually

If you supply a block to the breadcrumbs method, it will yield an array with the breadcrumb links so you can build the breadcrumbs HTML manually:

<% breadcrumbs do |links| %>
  <% if links.any? %>
    You are here:
    <% links.each do |link| %>
      <%= link_to link.text, link.url, class: (link.current? ? "current" : nil) %> (<%= link.key %>)
    <% end %>
  <% end %>
<% end %>

Getting the parent breadcrumb

If you want to add a link to the parent breadcrumb, you can use the parent_breadcrumb view helper. By default it returns a link instance that has the properties #key, #text, and #url. You can supply options like autoroot: false etc.

If you supply a block, it will yield the link if it is present:

<% parent_breadcrumb do |link| %>
  <%= link_to "Back to #{link.text}", link.url %>
<% end %>

Nice to know

Access to view methods

When configuring breadcrumbs inside a crumb :xx do ... end block, you have access to all methods that are normally accessible in the view where the breadcrumbs are inserted. This includes your view helpers, params, request, etc.

Using multiple breadcrumb configuration files

If you have a large site and you want to split your breadcrumbs configuration over multiple files, you can create a folder named config/breadcrumbs and put your configuration files (e.g. products.rb or frontend.rb) in there. The format is the same as config/breadcrumbs.rb which is also loaded.

Loading breadcrumbs from engines

Breadcrumbs are automatically loaded from any engines' config/breadcrumbs.rb and config/breadcrumbs/**/*.rb. Breadcrumbs defined in your main app will override breadcrumbs from engines.

Inferring breadcrumbs

Breadcrumbs can be automatically inferred if you pass an instance of an object that responds to model_name (like an ActiveRecord model instance).

For example:

<% breadcrumb @product %>

is short for

<% breadcrumb :product, @product %>

Passing options to links

You can pass options to links to be used when you render breadcrumbs manually.

In config/breadcrumbs.rb:

crumb :something do
  link "My Link", my_path, title: "My Title", other: "My Other Option"
end

Example methods you can then use in the view:

breadcrumbs do |links|
  links.each do |link|
    link.title?              # => true
    link.title               # => "My Title"
    link.other?              # => true
    link.other               # => "My Other Option"
    link.nonexisting_option? # => false
    link.nonexisting_option  # => nil
  end
end

Automatic reloading of breadcrumb configuration files

Since Gretel version 2.1.0, the breadcrumb configuration files are now reloaded in the Rails development environment if they change. In other environments, like production, the files are loaded once, when first needed.

Setting breadcrumb trails

The gretel-trails gem can handle adding and hiding trails from the URL automatically. This makes it possible to link back to a different breadcrumb trail than the one specified in your breadcrumb, for example if you have a store with products that have a default parent to the category breadcrumb, but when visiting from the reviews section, you want to link back to the reviews instead.

You can apply trails to select links by adding a simple JS selector (js-append-trail or another you choose), and after each page load it hides the trail from the URL, so the server sees it but the users don't.

Check out the gem here.

Upgrading from version 2.0 or below

Instead of using the initializer that in Gretel version 2.0 and below required restarting the application after breadcrumb configuration changes, the configuration of the breadcrumbs is now loaded from config/breadcrumbs.rb (and config/breadcrumbs/*.rb if you want to split your breadcrumbs configuration across multiple files). In the Rails development environment, these files are automatically reloaded when changed.

Using the initializer (e.g. config/initializers/breadcrumbs.rb) was deprecated in Gretel version 2.1.0 and removed in version 3.0. It raises an error if you try to use it.

To update to the latest version of Gretel, use bundle update gretel. Then remove the Gretel::Crumbs.layout do ... end block, so instead of:

Gretel::Crumbs.layout do
  crumb :root do
    link "Home", root_path
  end
end

in the initializer, you write:

crumb :root do
  link "Home", root_path
end

in config/breadcrumbs.rb.

Documentation

• Full documentation
• Changelog

Versioning

Follows semantic versioning.

Contributing

You are very welcome to help improve Gretel if you have suggestions for features that other people can use.

To contribute:

1. Fork the project
2. Create your feature branch (git checkout -b my-new-feature)
3. Make your changes
4. Add tests
5. Prep test database:
   • cd test/dummy
   • rake db:test:prepare
   • rake db:migrate
6. Run rake to make sure all tests pass
   • cd test
   • rake
7. Commit your changes (git commit -am 'Add new feature')
8. Push to the branch (git push origin my-new-feature)
9. Create new pull request

Thanks.

Contributors

• See the list of contributors

And then

Have fun!

Copyright (c) 2010-2013 Lasse Bunk, released under the MIT license