(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 – lassebunk@gmail.com.

In your Gemfile:

gem "gretel"

And run:

$ bundle install

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

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

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

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.

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 # inferred to :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.parent # inferred to :category
  else
    parent :categories
  end
end

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

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 %>

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 %>

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.

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.

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.

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 %>

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

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.

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.

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.

• Full documentation
• Changelog
• Tutorial on using Gretel (Sitepoint)

Follows semantic versioning.

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/Fix tests
5. Prepare database for testing: cd test/dummy; rake db:migrate; rake db:test:prepare; cd ../..
6. Run rake to make sure all tests pass
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.

Gretel was created by @lassebunk and is maintained by @WilHall.

See the list of contributors

Have fun!

Copyright (c) 2010-2016 Lasse Bunk, released under the MIT license