module Sinatra::ContentFor
Sinatra::ContentFor
¶ ↑
Sinatra::ContentFor
is a set of helpers that allows you to capture blocks inside views to be rendered later during the request. The most common use is to populate different parts of your layout from your view.
The currently supported engines are: Erb, Erubi, Haml and Slim.
Usage¶ ↑
You call content_for
, generally from a view, to capture a block of markup giving it an identifier:
# index.erb <% content_for :some_key do %> <chunk of="html">...</chunk> <% end %>
Then, you call yield_content
with that identifier, generally from a layout, to render the captured block:
# layout.erb <%= yield_content :some_key %>
If you have provided yield_content
with a block and no content for the specified key is found, it will render the results of the block provided to yield_content.
# layout.erb <% yield_content :some_key_with_no_content do %> <chunk of="default html">...</chunk> <% end %>
Classic Application¶ ↑
To use the helpers in a classic application all you need to do is require them:
require "sinatra" require "sinatra/content_for" # Your classic application code goes here...
Modular Application¶ ↑
To use the helpers in a modular application you need to require them, and then, tell the application you will use them:
require "sinatra/base" require "sinatra/content_for" class MyApp < Sinatra::Base helpers Sinatra::ContentFor # The rest of your modular application code goes here... end
And How Is This Useful?¶ ↑
For example, some of your views might need a few javascript tags and stylesheets, but you don’t want to force this files in all your pages. Then you can put <%= yield_content :scripts_and_styles %>
on your layout, inside the <head> tag, and each view can call content_for
setting the appropriate set of tags that should be added to the layout.
Limitations¶ ↑
Due to the rendering process limitation using <%= yield_content %>
from within nested templates do not work above the <tt><%= yield %> statement. For more details github.com/sinatra/sinatra-contrib/issues/140#issuecomment-48831668
# app.rb get '/' do erb :body, :layout => :layout do erb :foobar end end # foobar.erb <% content_for :one do %> <script> alert('one'); </script> <% end %> <% content_for :two do %> <script> alert('two'); </script> <% end %>
Using <%= yield_content %>
before <%= yield %>
will cause only the second alert to display:
# body.erb # Display only second alert <%= yield_content :one %> <%= yield %> <%= yield_content :two %> # body.erb # Display both alerts <%= yield %> <%= yield_content :one %> <%= yield_content :two %>
Public Instance Methods
Source
# File lib/sinatra/content_for.rb, line 155 def clear_content_for(key) content_blocks.delete(key.to_sym) if content_for?(key) end
Unset a named block of content. For example:
<% clear_content_for :head %>
Source
# File lib/sinatra/content_for.rb, line 132 def content_for(key, value = nil, options = {}, &block) block ||= proc { |*| value } clear_content_for(key) if options[:flush] content_blocks[key.to_sym] << capture_later(&block) end
Capture
a block of content to be rendered later. For example:
<% content_for :head do %> <script type="text/javascript" src="/foo.js"></script> <% end %>
You can also pass an immediate value instead of a block:
<% content_for :title, "foo" %>
You can call content_for
multiple times with the same key (in the example :head
), and when you render the blocks for that key all of them will be rendered, in the same order you captured them.
Your blocks can also receive values, which are passed to them by yield_content
Source
# File lib/sinatra/content_for.rb, line 148 def content_for?(key) content_blocks[key.to_sym].any? end
Check if a block of content with the given key was defined. For example:
<% content_for :head do %> <script type="text/javascript" src="/foo.js"></script> <% end %> <% if content_for? :head %> <span>content "head" was defined.</span> <% end %>
Source
# File lib/sinatra/content_for.rb, line 176 def yield_content(key, *args, &block) if block_given? && !content_for?(key) haml? && Tilt[:haml] == Tilt::HamlTemplate && respond_to?(:capture_haml) ? capture_haml(*args, &block) : yield(*args) else content = content_blocks[key.to_sym].map { |b| capture(*args, &b) } content.join.tap do |c| if block_given? && (erb? || erubi?) @_out_buf << c end end end end
Render the captured blocks for a given key. For example:
<head> <title>Example</title> <%= yield_content :head %> </head>
Would render everything you declared with content_for :head
before closing the <head>
tag.
You can also pass values to the content blocks by passing them as arguments after the key:
<%= yield_content :head, 1, 2 %>
Would pass 1
and 2
to all the blocks registered for :head
.
Private Instance Methods
Source
# File lib/sinatra/content_for.rb, line 191 def content_blocks @content_blocks ||= Hash.new { |h, k| h[k] = [] } end