monkey patch in MoreLikeThis for Blacklight

blacklight_config.rb

Blacklight.configure(:shared) do |config|
[...]
config[:mlt_fields] = ['people', 'place', 'date', 'topic']
[...]
end

mlt_patch.rb

require 'dispatcher'

module Mlt_SolrHelperPatch
        def self.included(base)
                base.extend(ClassMethods)
                base.send(:include, InstanceMethods)
        end

        module ClassMethods

        end
        module InstanceMethods
          def more_like_this(id = nil, extra_controller_params={})
            input = ({:mlt => true, 'mlt.fl' => Blacklight.config[:mlt_fields], 'mlt.mindf' => 1, 'mlt.mintf' => 1, 'mlt.count' => 3 }).deep_merge(extra_controller_params)
            response, document = get_solr_response_for_doc_id(id, input)
            response['moreLikeThis'].first.last['docs'].collect {|doc| SolrDocument.new(doc)}
          end
        end
end
  
    
Dispatcher.to_prepare do
  Blacklight::SolrHelper.send(:include, Mlt_SolrHelperPatch) 
end 

viz_controller.rb

class VizController < ApplicationController
  include Blacklight::SolrHelper
[...]
  def show
    @response, @document = get_solr_response_for_doc_id
    @similar = more_like_this nil, {'mlt.count' => 30}

    respond_to do |format|
      format.html { render :layout => false }
    end
  end
end