Question

I’d like to make changes to the Jekyll Only First Paragraph plugin to make the generation of a ‘read more ‘ link a configurable option.

To do this I’d need to be able to access the Jekyll site config inside the plugin’s AssetFilter. With the configuration available I can make the change. I don’t know how to make the site configuration available to the plugin.

The code below demonstrates where I’d like site.config available:

require 'nokogiri'

module Jekyll
  module AssetFilter
    def only_first_p(post)
      # site.config needs to be available here to modify the output based on the configuration

      output = "<p>"
      output << Nokogiri::HTML(post["content"]).at_css("p").inner_html
      output << %{</p><a class="readmore" href="#{post["url"]}">Read more</a>}

      output
    end
  end
end

Liquid::Template.register_filter(Jekyll::AssetFilter)

Can this be achieved?

Answer 1

Overview

You can access Jekyll config options in plugins with:

Jekyll.configuration({})['KEY_NAME']

If the config key contains nested levels, the format is:

Jekyll.configuration({})['KEY_LEVEL_1']['KEY_LEVEL_2']

---

Example

If a _config.yml contains:

testvar: new value

custom_root:
    second_level: sub level data

A basic example that simply outputs those values would look like:

require 'nokogiri'

module Jekyll
  module AssetFilter
    def only_first_p(post)

      @c_value = Jekyll.configuration({})['testvar']
      @c_value_nested = Jekyll.configuration({})['custom_root']['second_level']

      output = "<p>"

      ### Confirm you got the config values
      output << "<br />"
      output << "c_value: " + @c_value + "<br />"
      output << "c_value_nested: " + @c_value_nested + "<br />"
      output << "<br />"
      ###

      output << Nokogiri::HTML(post["content"]).at_css("p").inner_html
      output << %{</p><a class="readmore" href="#{post["url"]}">Read more</a>}

      output
    end
  end
end

Liquid::Template.register_filter(Jekyll::AssetFilter)

Of course, you would want to put checks in that verify that the config key/values are defined before trying to use them. That’s left as an exercise for the reader.

---

Another Possible Option

The “Liquid filters” section of the Jekyll Plugins Wiki Page contains the following:

In Jekyll you can access the site object through registers. As an example, you can access the global configuration (_config.yml) like this: @context.registers[:site].config[‘cdn’].

I haven’t spent the time to get that to work, but it might be worth checking out as well.