Plugin allows to specify outer layouts for particular layout thus creating nested layouts.
Let’s assume you have controller which action ‘hello’ just was called. Controller was set up to use ‘inner’ layout:
app/controllers/hello_controller.rb
class HelloController < ApplicationController
layout 'inner'
def hello
render :text => 'Hello, world!'
end
end
app/views/layouts/inner.rhtml
<% inside_layout 'outer' do -%>
<div class="hello">
<h1>Greetings</h1>
<%= yield %>
</div>
<% end -%>
app/views/layouts/outer.rhtml
<html>
<body>
<div class="content">
<%= yield %>
</div>
</body>
</html>
Result will look like this (formatted for better reading):
<html>
<body>
<div class="content">
<div class="hello">
<h1>Greetings</h1>
Hello, world!
</div>
</div>
</body>
</html>
Concept of layout nesting here is based on the assumption that every inner layout is used only to customize it’s outer layout and thus every inner layout is used only with one specific outer layout. With this in mind we can conclude that every layout must know it’s outer layout and thus information about outer layout must be embeded directly into inner layout. Controller doesn’t need to know about the whole stack of layouts, so you should just specify the most inner layout in it.
You can pass data from inner layout to outer one, e.g.:
layouts/inner.rhtml
<% content_for 'menu' do -%>
<ul>
<li><a href="about_us">About Us</a></li>
<li><a href="products">Products</a></li>
</ul>
<% end -%>
<% inside_layout 'outer' do -%>
<% @other_data_for_outer_layout = 'foo' -%>
<%= yield %>
<% end -%>
layouts/outer.rhtml
<%= yield 'menu' %>
<br/>
The data was: <%= @other_data_for_outer_layout %>
<br/>
<%= yield %>
Instead of using layout stored in file system, you can use inside_inline_layout to wrap template part into some template code passed as a string. It is usefull if you want to use layouts that are stored in DB:
Layout model
class Layout < ActiveRecord::Base
# Has attributes 'name' and 'contents'
end
Helper
module ApplicationHelper
def inside_db_layout(name, &block)
layout = Layout.find_by_name(name)
template = layout ? layout.contents : '<%= yield %>'
inside_inline_layout(template, &block)
end
end
View
<% inside_db_layout 'layout_from_db1' do %>
Content
<% end %>
This plugin was originally written by Maxim Culkin (maxim_culkin@gmail.com)
Forked by Jeff Wigal (jeff@referee-assistant.com), patched to be compatible with Rails 2.2+
./script/plugin install git://github.com/jwigal/nested_layouts.git
Original project page:
http://rubyforge.org/projects/nested-layouts/
If you encounter any bugs or has some feature proposal, feel free to email it to jeff@referee-assistant.com.