Getting Liquid to Work in Rails

Using .liquid as a template handler in your views

Liquid comes with a proper init.rb file, by default.
To start using Liquid, just extract it into vendor/plugins.
Better yet, use the ./script/plugin script to install Liquid.

You can now start using templates with the .liquid file type (ie, extension).

Helpers become filters

A note about helpers.
Liquid’s Rails plugin tries to use your helpers as Filters.
Your helpers will always receive the piped-in text as the first parameter,
and then any Filter parameters (passed after the colon).

Helper:

module ApplicationHelper

  def truncate(input, length)

    input[0..length] + ‘…’ 

  end

end

Liquid:

{{ ‘This is a long section of text’ | truncate: 3 }} #=>   Thi… 

Using .liquid as a layout

Insert

{{ content_for_layout }}

in your liquid layout where you would put <%= yield %> in an erb layout.

Note: if you are collecting content with <% content_for :foo do %> ... <% end %> then there is currently no way to access this in a liquid layout.

Using Rails model data and methods in Liquid templates

When you pass variables to be available in a Liquid template,
Liquid accepts a limited number of object types —
Strings, Arrays, Hashes, Numerics, and Booleans.
If you’d like to pass your ActiveRecord (or other) objects to a Liquid template,
you have three basic approaches:

The easy way is to add a liquid_methods call:

class Post < ActiveRecord::Base
  liquid_methods :title, :body, :comments
...

Behind the scenes,
liquid_methods actually constructs a
Liquid Drop with the methods you include.
This way, you have lazy loading
(say, of associated models such as “comments” in the example above) of methods.

An alternate route is to add a to_liquid call in your object,
returning either one of the types listed above (string, array, hash, etc)
or an object that in turn responds to to_liquid.

class Post < ActiveRecord::Base
...
 def to_liquid
    {'title' => title, 'body' => body}
  end

Finally, you can write and register a completely new
Liquid Drop class.
This enables you to pull from various models
and helps you consolidate (lazy-loaded) methods used just for passing data to templates.