A solid Breadcrumb for Rails. You do not need to dirty your controllers with a bunch of code. Breadcrumby is a really relational breadcrumb.

Add the following code on your Gemfile and run bundle install:

gem 'breadcrumby'

With the following example of ActiveRecord relations:

class School
  def show_path
    "/schools/#{id}"
  end
end

class Course
  belongs_to :school

  def show_path
    "/courses/#{id}"
  end
end

Let's make it know about the breadcrumb path:

class School
  breadcrumby

  def show_path
    "/schools/#{id}"
  end
end

Now school knows how to buid the breadcrumb but since it has no path it will be the last item.

So, we need to teach the Course class how to follow the path until School:

class Course
  breadcrumby path: :school

  belongs_to :school

  def show_path
    "/courses/#{id}"
  end
end

Now Breadcrumby know how to fetch the path, using the belongs_to relation.

With a instance of Course that has a relation with School, we can build the breadcrumb:

<%= breadcrumby @course %>

And the result will be: Home / School / Course

Breadcrumby uses the semantic Breadcrumb HTML from Google:

<ol class="breadcrumby" itemscope itemtype="http://schema.org/BreadcrumbList">
  <li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem">
    <a itemprop="item" itemscope itemtype="http://schema.org/Thing" title="{name}" href="{show_path}">
      <span itemprop="name">{name}</span>
    </a>

    <meta content="1" itemprop="position">
  </li>
</ol>

• name: Fetched from method name of the model;
• show_path: Fetched from method show_path of the model.

I18n configuration will always has priority over the model method.

As you could see, the Home crumb was generated automatically. You can customize the name with I18n and the show_path will be root_path or / by default.

You can add one last path on breadcrumb to indicate the current action you are doing, like a edition:

class School
  breadcrumby action: :edit
end

It generates a muted link on the end: Home / School / Edition

<ol class="breadcrumby" itemscope itemtype="http://schema.org/BreadcrumbList">
  <li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem">
    <a itemprop="item" itemscope itemtype="http://schema.org/Thing" title="Edition" href="javascript:void(0);">
      <span itemprop="name">Edition</span>
    </a>

    <meta content="3" itemprop="position">
  </li>
</ol>

All actions without actions option will try to follow path options. If it is a new object, it will have no relation and will raise error.

For actions like new where the object will be a new_record, we can customize the candidate to represent the self object. This way we can build a minimum path, not just Home / New. Let's say you have Unit on session and wants to set it on breadcrumb to say you are creating a Course on that unit of your school:

class Course
  breadcrumby actions: {
    new: -> (view) { Unit.find(view.session[:current_school][:id])
  }
end

Now the self object will be the new call result and the output will be:

Home / School / Unit / Courses / New

As you can see, the path will be completed from the self (new result) object. Plus, since the new object is not Unit, we need a context. It will be related with original model with value of index_path as path:

<a itemprop="item" itemscope="itemscope" itemtype="http://schema.org/Thing" title="List Courses" href="/courses">
  <span itemprop="name">Turmas</span>
</a>

Now it is possible to navigate to collection of items you want to create a new one.

You can customize some attributes via I18n to be fast and global:

en-US:
  breadcrumby:
    home:
      name: Home
      title: Home Page

    school:
      name: School
      title: "School: %{name}"

      actions:
        edit: # new / index / method_name ...
          name: Edition
          title: "Editing: %{name}"

• actions: Properties to change the actions crumb;
• name: The name of the crumb item;
• title: The title of the crum item with possibility of to use the name %{name}.

You can change the model key name, since the default search is the class method name:

class School
  breadcrumby i18n_key: :school_key
end

And now use:

en-US:
  breadcrumby:
    school_key:
      name: School

To make translations more generic just take it of inside the model name and it will be used for all models:

en-US:
  breadcrumby:
    actions:
      edit:
        name: Edition

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