WIP: store only one link check report

app/components/admin/editions/tags_component.rb

@@ -34,11 +34,11 @@ def limited_access_tag
   end
 
   def broken_links_report_tag
-    return unless edition.link_check_reports.any? && edition.link_check_reports.last.completed?
+    return unless edition.link_check_report.present? && edition.link_check_report.completed?
 
-    return create_tag("Broken links") if edition.link_check_reports.last.broken_links.any?
+    return create_tag("Broken links") if edition.link_check_report.broken_links.any?
 
-    create_tag("Link warnings") if edition.link_check_reports.last.caution_links.any?
+    create_tag("Link warnings") if edition.link_check_report.caution_links.any?
   end
 
   def create_tag(label)

app/controllers/admin/editions_controller.rb

@@ -106,7 +106,7 @@ def update
     if updater.can_perform? && @edition.save_as(current_user)
       updater.perform!
 
-      if @edition.link_check_reports.last
+      if @edition.link_check_report
         LinkCheckerApiService.check_links(@edition, admin_link_checker_api_callback_url)
       end
 
@@ -437,7 +437,7 @@ def edition_filter_options
       .symbolize_keys
       .merge(
         include_unpublishing: true,
-        include_link_check_reports: true,
+        include_link_check_report: true,
         include_last_author: true,
       )
       .merge(per_page: Admin::EditionFilter::GOVUK_DESIGN_SYSTEM_PER_PAGE)

app/models/admin/edition_filter.rb

@@ -124,7 +124,7 @@ def unpaginated_editions
       editions = editions.review_overdue if review_overdue
 
       editions = editions.includes(:unpublishing) if include_unpublishing?
-      editions = editions.includes(:link_check_reports) if include_link_check_reports?
+      editions = editions.includes(:link_check_report) if include_link_check_report?
       editions = editions.includes(:last_author) if include_last_author?
 
       @unpaginated_editions = editions
@@ -269,8 +269,8 @@ def include_unpublishing?
       options.fetch(:include_unpublishing, false)
     end
 
-    def include_link_check_reports?
-      options.fetch(:include_link_check_reports, false)
+    def include_link_check_report?
+      options.fetch(:include_link_check_report, false)
     end
 
     def include_last_author?

app/models/edition.rb

@@ -44,7 +44,7 @@ class Edition < ApplicationRecord
   has_many :edition_authors, dependent: :destroy
   has_many :authors, through: :edition_authors, source: :user
   has_many :topical_event_featurings, inverse_of: :edition
-  has_many :link_check_reports, as: :link_reportable, class_name: "LinkCheckerApiReport"
+  has_one :link_check_report, as: :link_reportable, class_name: "LinkCheckerApiReport"
 
   has_many :edition_dependencies, dependent: :destroy
   has_many :depended_upon_contacts, through: :edition_dependencies, source: :dependable, source_type: "Contact"

app/services/link_reporter_csv_service.rb

@@ -69,9 +69,9 @@ def timestamp(edition)
   end
 
   def broken_links(edition)
-    return [] if edition.link_check_reports.blank?
+    return [] if edition.link_check_report.nil?
 
-    edition.link_check_reports.last.broken_links.map(&:uri)
+    edition.link_check_report.broken_links.map(&:uri)
   end
 
   def edition_organisation(edition)

app/sidekiq/check_organisation_links_worker.rb

@@ -40,7 +40,7 @@ def find_organisation(organisation_id)
   end
 
   def public_editions(organisation)
-    least_recently_checked = Edition.includes(:link_check_reports).publicly_visible.with_translations.in_organisation(organisation).order("link_checker_api_reports.updated_at").limit(ORGANISATION_EDITION_LIMIT)
+    least_recently_checked = Edition.includes(:link_check_report).publicly_visible.with_translations.in_organisation(organisation).order("link_checker_api_reports.updated_at").limit(ORGANISATION_EDITION_LIMIT)
     Edition.where(id: least_recently_checked.pluck(:id))
   end
 end

app/views/admin/editions/edit.html.erb

@@ -41,7 +41,7 @@
            content: simple_formatting_sidebar(
              hide_inline_attachments_help: [email protected]_inline_attachments?,
              show_attachments_tab_help: true,
-             link_check_report: LinkCheckerApiService.has_links?(@edition, convert_admin_links: false) ? @edition.link_check_reports.last : nil,
+             link_check_report: LinkCheckerApiService.has_links?(@edition, convert_admin_links: false) ? @edition.link_check_report : nil,
            ),
          },
          {

app/views/admin/editions/show/_sidebar.html.erb

@@ -4,7 +4,7 @@
   <%= render(
         partial: "admin/link_check_reports/link_check_report",
         locals: {
-          report: (@edition.link_check_reports.last || @edition.link_check_reports.build),
+          report: (@edition.link_check_report || @edition.link_check_report.build),
           allow_new_report: true,
         },
       ) if show_link_check_report?(@edition) %>

db/data_migration/2025022610370000_remove_old_link_checker_reports.rb

@@ -0,0 +1,12 @@
+# To address https://github.com/alphagov/whitehall/issues/6011, we need
+# to remove old link checker reports and switch to a 'has_one' relationship.
+
+Edition.find_each do |edition|
+  reports = edition.link_check_reports.order(created_at: :desc).to_a
+  next if reports.size <= 1
+
+  # Keep the most recent report and delete the rest
+  reports_to_delete = reports.drop(1)
+  reports_to_delete.each(&:destroy)
+end
+