Breadcrumbs in Ruby on Rails_问答_开发者_运维开发者技术经验分享

I'm slightly insecure about my breadcrumb solution. Names and links are defined in each controller action:

<a href="http://localhost:3000/">Home</a>
<% if defined? @l1_link %>
  > <a href="<%= @l1_link%>"><开发者_JAVA百科;%= @l1_name %></a>
  <% if defined? @l2_link %>
    > <a href="<%= @l2_link%>"><%= @l2_name %></a>
  <% end %>
<% end %>

This way I can use:

@l1_link = user_path()

Question: As I am not that smart - could this kind of system lead to desaster somewhere down the road? Is this (grossly) inefficient?

Breadcrumbs menu are a recurrent pattern in most Rails applications. To solve this issue, I created and released a plugin called breadcrumbs_on_rails.

You define your breadcrumbs in the controller

class MyController

  add_breadcrumb "home", root_path
  add_breadcrumb "my", my_path

  def index
    # ...

    add_breadcrumb "index", index_path
  end

end

and you render them in your view.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
  <title>untitled</title>
</head>

<body>
  <%= render_breadcrumbs %>
</body>
</html>

Even if you don't want to use a plugin, I encourage you to give it a look. It's open source and you can grab some idea for your app.

I made a gem named Gretel that is a Ruby on Rails plugin for creating breadcrumbs. The breadcrumbs are configured in a separate configuration file and selected in the view.

Example config/breadcrumbs.rb:

crumb :root do
  link "Home", root_path
end

crumb :projects do
  link "Projects", projects_path
end

crumb :project do |project|
  link project.name, project_path(project)
  parent :projects
end

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

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

In your view:

<% breadcrumb :issue, @issue %>

In your app/views/layouts/application.html.erb:

<%= breadcrumbs pretext: "You are here: " %>

This is mostly a matter of opinion, but anyway:

I would not want that much logic in a view. We've probably all done it, but it gets messy quickly.
The code is not safe against future changes that affect the depth of the tree.
Instead of linked variables *_name and *_link, I'd suggest using proper objects anyway, with some link_to functionality.

You might find Episode 162 of Railscasts of interest for a nice solution that gets by with

<% for page in @page.ancestors.reverse %>
  <%= link_to h(page.name), page %> &gt;
<% end %>

Do not use any plugins just for breadcrumbs. This link provides an efficient method to generate breadcrumbs.

http://szeryf.wordpress.com/2008/06/13/easy-and-flexible-breadcrumbs-for-rails/

Although, it is a very old post, it still works.

You could also use Ariane http://github.com/simonc/ariane

With it you can generate any kind of breadcrumb, as links in a paragraph or as a ul/li :)

If you want something specific, you can create your own renderer.

It's pretty simple to use, just add this in a before_filter:

ariane.add 'Home', root_path # in the app controller to have it everywhere
ariane.add 'Some Page', some_path

I did a fork of crumble gem. It has very few configuration options and it appears abandoned, but when I tried to switch to breadcrumbs_on_rails or gretel, I realized that I have to add many lines to my views or controllers (and I have a lot of them), but with crumble it is all stored in one configuration file. If you like to do some patches and prefer configuration in one place, I think it is the best solution ever.