blacklight_config.rb

Blacklight.configure(:shared) do |config|
  #...
  SolrDocument.use_extension(YourModule)
  #...
end

YourController.rb

class YourController < ApplicationController
  def my_json
    response, @document = get_solr_response_for_doc_id
    render :text => @document.my_json, :layout => false
  end

  def our_json
    response, @document = get_solr_response_for_doc_id
    render :text => @document.export_as(:our_json), :layout => false
  end
end

YourModule.rb

module YourModule
  # This is the simplest implementation
  def my_json
    return {:this_is_my_json => ["Thing1","Thing2"]}.to_json
  end


  # This uses the export_as functionality.  This will make the JSON a true export format which will be auto-discoverable.
  def self.extended(document)
    document.export_as(:our_json,"application/json")
  end
  private
  def export_as_our_json
    return {:this_is_our_json => ["Thing1","Thing2"]}.to_json
  end
end