First steps in Nesta (and Ruby)

Note: this article was updated to work with Redcarpet 2, that is incompatible with first version.

In order to use custom content processing libarary (I wanted to try out new markdown lib from github, Redcarpet) I needed to extend Nesta's FileModel's to_html method, like so:

module Nesta 
  class FileModel 
    def to_html ( scope = nil )
      html = convert_to_html @format, scope, markup
    end

def convert_to_html ( format, scope, text )
  @markdown = Redcarpet::Markdown.new(
                Redcarpet::Render::HTML,
                :no_intra_emphasis => true,
                :lax_html_blocks => true,
                :autolink => true, 
                :space_after_headers => true
              )

case format
  when :mdown
    @markdown.render( text )
    # Maruku.new( text ).to_html
  when :haml
    Haml::Engine.new( text ).to_html(scope || Object.new)
  when :textile
    RedCloth.new( text ).to_html
  end
        end
      end
    end

That allows me to parse content files with Redcarpet instead of default markdown parser, Maruku. But what if I also want to use :redcarpet as a filter in HAML? In order to do that, I needed to add new HAML filter:

module Haml::Filters::Redcarpet
  include Haml::Filters::Base

@markdown = Redcarpet::Markdown.new(
              Redcarpet::Render::HTML,
              :no_intra_emphasis => true,
              :lax_html_blocks => true,
              :autolink => true, 
              :space_after_headers => true
            )

def render ( text )
  @markdown.render text
end
    end

We can now use :redcarpet filter in HAML like so:

%p
  :redcarpet
    # Here goes markdown content

Another useful note: @page.metadata() method is exposed, i.e. you can specify any key in the top of your pages and you'll be able to access that data in your templates like so:

- if @page.metadata('foo')
  %h1 @page.metadata('foo')

It's important to note, that if you are going to retrieve values from @page in layout, guard yourself with ifs, because there are pages like 404, that are using layout but don't have associated @page model with them, – in that case you wont have @page defined, and calling @page.method will break.

Sources

1. https://github.com/gma/nesta/blob/master/lib/nesta/models.rb
2. https://github.com/gma/nesta/issues#issue/21