BlueTree

Bluetree is a module of methods which allow you to create composable view classes. Each class instance is initialized with an ERB template. The templates of these views have access to all local instance variables and methods plus access to the immediate parent and root node objects.

Add this line to your application's Gemfile:

gem 'blue_tree'

And then execute:

$ bundle

Or install it yourself as:

$ gem install blue_tree

Say you wanted to create a composite view using a couple of different classes:

require 'blue_tree'

class Page
  include BlueTree::Node
  use_template_path "path/to/my/templates" # defaults to "YOUR_GEM_PATH/templates"
  use_template_ext  ".foo.erb"             # defaults to ".html.erb"
  
  attr_reader :page_title, :introduction, :conclusion
  # More Page specific code...
end

class Section
  include BlueTree::Node

  attr_reader :title, :description
  # More Section specific code...
end

Set up your nodes (The symbol argument is the basename of the ERB template file):

main_page   = Page.new(:page_template)
section     = Section.new(:section_template)
sub_section = Section.new(:sub_section_template)

Compose your nodes:

section.add_child sub_section
main_page.add_child section

What you can reference in the templates:

• any methods and variables in the current object
• children_nodes - returns an array of child node objects
• parent_node - returns the immediate parent object
• root_node - returns the root object

So for example, the sub_section template might look like this:

<h2><%= title %> (Part of the <%= root_node.page_title %> series)</h2>
<p>This follows on from the <%= parent_node.title %> section.</p>
<p><%= description %></p>

It's up to the templates to render any children nodes - so the main page template might look like this (the trailing dash notation is accepted):

<h1><%= page_title %></h1>
<p><%= introduction %></p>
<% child_nodes.each do |c| -%>
  <%= c.render %>
<% end -%>
<p><%= conclusion %></p>

Rendering:

main_page.render # => returns the recursively rendered string

You can also render templates not associated with any nodes by using the render_template method. This can be useful if you want to reuse common templates like headers or footers. The template must exist in your template_path. Like any node, it has access to all variables and methods in the current object, the parent object and the root object:

...
<%= render_template(:common_footer_template) %>

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request