How to get Markdown processed content in Jekyll tag plugin

Question

I'm working on a Jekyll tag plugin for my Octopress site to help me make a 'note' element. I just want to be able to highlight a piece of information on my blog as a side note, like this.

The problem is, I can't figure out how to get the contents of this tag to be processed (i.e. Markdown or Textile). The above image is only achieved is I actually make my links with html code. Here is how it ends up turning out when I use markdown in the contents.

In my post, I'm writing the contents of this like so.

{% note %}
This is the third post in my Start to Finish series.  Last time I talked about [Git](/blog/2013/09/25/getting-started-with-git/).
{% endnote %}

Here is my plugin code. It's based off of the image tag code, and there's really not a lot to it.

module Jekyll
  class NoteTag < Liquid::Block
    @title = nil

    def initialize(tag_name, markup, tokens)
      @title = markup
      super
    end

    def render(context)
      output = super(context)
      title = "Note"
      if [email protected]?
        title += ": #{@title}"
      end
      "</section>\n<div class=\"note\"><span class=\"title\">#{title}</span>#{output}</div>\n<section>"
    end
  end
end

Liquid::Template.register_tag('note', Jekyll::NoteTag)

Do you have any idea how I can use a converter on the contents of this tag? I generally use Markdown for my posts, but I'd like to release this plugin for others so I'd like it to be dynamic just like the rest of Jekyll.

Answer 1

I found this implementation of a 'Markdown block tag' which seems to be a relatively straightforward implementation. Note the use of site.getConverterImpl() in the render method.

I used that example to produce this figure tag (based on prior art to another question I found on SO but can no longer locate)

module Jekyll
  module Tags
    class FigureTag < Liquid::Block

      CaptionUrl = /(\S[\S\s]*)\s+(https?:\/\/\S+)\s+(.+)/i
      Caption = /(\S[\S\s]*)/

      def initialize(tag_name, markup, tokens)
        super
        @caption = nil
        if markup =~ CaptionUrl
          @caption = "\n\t\t<figcaption>#{$1}<a href='#{$2}'>#{$3}</a></figcaption>\n\t"
        elsif markup =~ Caption
          @caption = "\n\t\t<figcaption>#{$1}</figcaption>\n\t"
        end
        @markup = markup
      end

      def render(context)
        site = context.registers[:site]
        converter = site.getConverterImpl(::Jekyll::Converters::Markdown)
        output = converter.convert(super(context))
        "<figure class=\"center\">#{output}#{@caption}</figure>"
      end
    end
  end
end

Liquid::Template.register_tag('fig', Jekyll::Tags::FigureTag)

The above plugin manages to parse markdown within the contents of the block. So given the following block tag usage:

{% fig Test fig %}
This should be parsed as *markdown* [man](http://example.com/).
{% endfig %}

You'll get the following html:

<figure class="center"><p>This should be parsed as <em>markdown</em> <a href="http://example.com/">man</a>.</p>
    <figcaption>Test fig </figcaption>
</figure>

Hope this helps! I spent a couple hours last night and got nowhere, but this morning I found this example and it clicked within 20 minutes.

Answer 2

Jekyll 3.x : getConverterImpl is now deprecated

Use find_converter_instance to get the converter :

def render(context)
  text = super
  site = context.registers[:site]
  converter = site.find_converter_instance(::Jekyll::Converters::Markdown)
 _output += "<figcaption>#{converter.convert(_caption)}</figcaption>"