no_querying_views.rb

if Rails.env.development?
  module ::ActiveRecord
    module ConnectionAdapters
      %w(PostgreSQLAdapter MysqlAdapter SQLite3Adapter).each do |adapter_name|
        begin
          adapter = const_get adapter_name
          adapter.class_eval do
            puts "[WARNING] NoQueryingViews is preventing your views from triggering PG, MySQL or SQLite3 database connections.  (To permit this, remove the initializer.)" 
            alias :orig_execute :execute
            def execute(*args)
              first_view   = caller.grep(/app\/views/).first
              first_helper = caller.grep(/app\/helpers/).first

              # if we're coming from a view, let's analyze the situation
              if !first_view.nil? and (first_helper.nil? or (caller.index(first_view) < caller.index(first_helper)))
                raise "No query from view prohibited, eager-load from a controller instead."
              else
                orig_execute *args
              end
            end
          end
        rescue
          # the adapter has not been instantiated
        end
      end
    end
  end
end