Extending the CatalogController

In (Model, View, Controller, and Rails Engines)[/v7.11.1/mvc-routing-engines], we created a separate home page controller that displays only static text. Now we’d like to put a selection of facet fields on that page.

First, we need to pull in the Blacklight configuration from the CatalogController, query Solr, and render the facets. The most expedient way to do that, perhaps, is to change the StaticPagesController to have it inherit from CatalogController (pulling in the Blacklight configuration automatically, and, through Rails magic, setting everything up so we can easily render the same partials):

- class StaticPagesController < ApplicationController
+ class StaticPagesController < CatalogController

If we try to look at the home page now, we’ll see a routing error (ActionController::UrlGenerationError in StaticPages#home). We’ll also need to tell the StaticPagesController we want to use the catalog routes from CatalogController ¹. By convention, Blacklight uses the search_action_url method to route to the correct place. We can override that in the controller:

class StaticPagesController < CatalogController
+  alias_method :search_action_url, :search_catalog_url

Next, we need to update the controller to make a solr query and store the result (again, by convention) in the instance variable @response. We can copy the way Blacklight does this for the CatalogController#index action ²:

class StaticPagesController < CatalogController
  ...
  def home
+   (@response, _) = search_service.search_results
  end
end

Then, we need to render some facets into the view. In app/views/static_pages/home.html.erb, we can have Rails render the normal facets partial:

<% content_for(:sidebar) do %>
  <%= render 'facets' %>
<% end %>

<h1>StaticPages#home</h1>
<p>Find me in app/views/static_pages/home.html.erb</p>

Now that we have facets rendering, we might choose a subset of the full result (due to user experience research suggesting a couple common entry points, or for performance reasons). To do this, we can re-open the search configuration and re-arrange it however we want, say to limit the facets to just format and publication date:

class StaticPagesController < CatalogController
  configure_blacklight do |config|
    config.facet_fields.slice!('format', 'pub_date_ssim')
  end

config.facet_fields is just an ordinary Ruby hash, so we can mutate it by adding, changing, or removing values.