Change default search_results behavior to grouped by collection

app/controllers/catalog_controller.rb

@@ -13,6 +13,7 @@ class CatalogController < ApplicationController
   include Arclight::Catalog
 
   include UmArclight::Catalog
+  prepend_before_action :default_to_grouped_results, only: :index
 
   configure_blacklight do |config|
     ## Class for sending and receiving requests from a search index
@@ -450,4 +451,10 @@ class CatalogController < ApplicationController
     # Group header values
     config.add_group_header_field "abstract_or_scope", accessor: true, truncate: true, helper_method: :render_html_tags
   end
+
+  private
+
+  def default_to_grouped_results
+    params[:group] = "true" if params[:group].blank?
+  end
 end

app/helpers/um_arclight_helper.rb

@@ -6,6 +6,12 @@ def homepage?
     current_page?(root_path) && !has_search_parameters?
   end
 
+  def search_without_group
+    search_state.params_for_search
+                .merge("group" => "false")
+                .except("page")
+  end
+
   def formatted_last_indexed(timestamp)
     date = DateTime.parse(timestamp)
     date.strftime("%F")