gistfile1.rb

module MyApp
  class IncViewsCounterFor < ::Liquid::Tag

    Syntax = /(#{::Liquid::Expression}+)?/

    def initialize(tag_name, markup, tokens, context)
      if markup =~ Syntax
        @name = $1
      else
        raise ::Liquid::SyntaxError.new("Syntax Error in 'inc_views_counter_for' - Valid syntax: inc_views_counter_for <content>")
      end

      super
    end

    def render(context)
      model = context[@name] # returns a liquid drop object (Locomotive::Liquid::Drops:Content)

      model._source.inc(:views_counter, 1) # mongoid command

      '' # returns an empty string since this tag does not have to write to the output
    end

  end

  ::Liquid::Template.register_tag('inc_views_counter_for', IncViewsCounterFor)
end