Allow client to request only current role appointments

The prime minister page does not need the former role appointments to
render, so there is no need to retrieve them.

By adding an argument to the `role_appointments` link field, we can
reduce the number of documents whose links need to be further expanded.

An index for editions with a current value in the details was added in
e1b1955.

app/graphql/sources/reverse_linked_to_editions_source.rb

@@ -1,18 +1,34 @@
 module Sources
   class ReverseLinkedToEditionsSource < GraphQL::Dataloader::Source
     # rubocop:disable Lint/MissingSuper
-    def initialize(parent_object:)
+    def initialize(parent_object:, only_current: false)
       @object = parent_object
       @content_store = parent_object.content_store.to_sym
+      @only_current = only_current
     end
     # rubocop:enable Lint/MissingSuper
 
     def fetch(link_types)
-      all_links = @object
-        .document
-        .reverse_links
-        .includes(source_documents: @content_store)
-        .where(link_type: link_types)
+      all_links = if @only_current
+                    query = <<~SQL
+                      SELECT links.*
+                      FROM links
+                      LEFT JOIN link_sets ON links.link_set_id = link_sets.id
+                      LEFT JOIN documents AS link_set_link_documents ON link_sets.content_id = link_set_link_documents.content_id
+                      LEFT JOIN editions AS link_set_link_editions ON link_set_link_documents.id = link_set_link_editions.document_id
+                      LEFT JOIN editions AS edition_link_editions ON links.edition_id = edition_link_editions.id
+                      WHERE links.target_content_id = '#{@object.content_id}'
+                      AND links.link_type IN (#{link_types.map { |type| "'#{type}'" }.join(',')})
+                      AND (link_set_link_editions.content_store = '#{@content_store}' OR edition_link_editions.content_store = '#{@content_store}')
+                      AND (link_set_link_editions.details ->> 'current' = 'true' OR edition_link_editions.details ->> 'current' = 'true')
+                    SQL
+
+                    Link.from("(#{query}) AS links")
+                  else
+                    Link
+                      .where(target_content_id: @object.content_id, link_type: link_types)
+                      .includes(source_documents: @content_store)
+                  end
 
       link_types_map = link_types.index_with { [] }
 

app/graphql/types/base_object.rb

@@ -19,7 +19,7 @@ def self.reverse_links_field(field_name_and_link_type, belongs_to, graphql_field
       field(field_name_and_link_type.to_sym, graphql_field_type)
 
       define_method(field_name_and_link_type.to_sym) do
-        dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object)
+        dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object, only_current: false)
           .load(belongs_to.to_s)
       end
     end

app/graphql/types/edition_type.rb

@@ -99,14 +99,16 @@ class EditionLinks < Types::BaseObject
       reverse_links_field :related_to_step_navs, :pages_related_to_step_nav, [EditionType]
       reverse_links_field :secondary_to_step_navs, :secondary_to_step_navs, [EditionType]
 
-      field :role_appointments, [EditionType]
+      field :role_appointments, [EditionType] do
+        argument :only_current, Boolean, required: false, default_value: false
+      end
 
-      def role_appointments
+      def role_appointments(only_current:)
         if %w[role ministerial_role].include?(object.document_type)
-          dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object)
+          dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object, only_current:)
             .load("role")
         else
-          dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object)
+          dataloader.with(Sources::ReverseLinkedToEditionsSource, parent_object: object, only_current:)
             .load("person")
         end
       end

spec/graphql/sources/reverse_linked_to_editions_source_spec.rb

@@ -1,45 +1,98 @@
 RSpec.describe Sources::ReverseLinkedToEditionsSource do
-  it "returns the specified reverse link set links" do
-    target_edition = create(:edition)
-    source_edition_1 = create(:edition)
-    source_edition_2 = create(:edition)
-    source_edition_3 = create(:edition)
-    link_set_1 = create(:link_set, content_id: source_edition_1.content_id)
-    link_set_2 = create(:link_set, content_id: source_edition_2.content_id)
-    link_set_3 = create(:link_set, content_id: source_edition_3.content_id)
-    create(:link, link_set: link_set_1, target_content_id: target_edition.content_id, link_type: "test_link")
-    create(:link, link_set: link_set_2, target_content_id: target_edition.content_id, link_type: "another_link_type")
-    create(:link, link_set: link_set_3, target_content_id: target_edition.content_id, link_type: "test_link")
-
-    GraphQL::Dataloader.with_dataloading do |dataloader|
-      request = dataloader.with(described_class, parent_object: target_edition).request("test_link")
-
-      expect(request.load).to eq([source_edition_1, source_edition_3])
+  context "when only_current is not set" do
+    it "returns the specified reverse link set links" do
+      target_edition = create(:edition)
+      source_edition_1 = create(:edition)
+      source_edition_2 = create(:edition)
+      source_edition_3 = create(:edition)
+      link_set_1 = create(:link_set, content_id: source_edition_1.content_id)
+      link_set_2 = create(:link_set, content_id: source_edition_2.content_id)
+      link_set_3 = create(:link_set, content_id: source_edition_3.content_id)
+      create(:link, link_set: link_set_1, target_content_id: target_edition.content_id, link_type: "test_link")
+      create(:link, link_set: link_set_2, target_content_id: target_edition.content_id, link_type: "another_link_type")
+      create(:link, link_set: link_set_3, target_content_id: target_edition.content_id, link_type: "test_link")
+
+      GraphQL::Dataloader.with_dataloading do |dataloader|
+        request = dataloader.with(described_class, parent_object: target_edition).request("test_link")
+
+        expect(request.load).to eq([source_edition_1, source_edition_3])
+      end
+    end
+
+    it "returns the specified reverse edition links" do
+      target_edition = create(:edition)
+
+      source_edition_1 = create(:edition,
+                                links_hash: {
+                                  "test_link" => [target_edition.content_id],
+                                })
+
+      source_edition_2 = create(:edition,
+                                links_hash: {
+                                  "test_link" => [target_edition.content_id],
+                                })
+
+      create(:edition,
+             links_hash: {
+               "another_link_type" => [target_edition.content_id],
+             })
+
+      GraphQL::Dataloader.with_dataloading do |dataloader|
+        request = dataloader.with(described_class, parent_object: target_edition).request("test_link")
+
+        expect(request.load).to eq([source_edition_1, source_edition_2])
+      end
     end
   end
 
-  it "returns the specified reverse edition links" do
-    target_edition = create(:edition)
+  context "when only_current is set" do
+    it "returns the specified reverse link set links for current role appointments only" do
+      target_edition = create(:edition)
+      source_edition_1 = create(:edition, details: { current: true })
+      source_edition_2 = create(:edition, details: { current: true })
+      source_edition_3 = create(:edition, details: { current: false })
+      link_set_1 = create(:link_set, content_id: source_edition_1.content_id)
+      link_set_2 = create(:link_set, content_id: source_edition_2.content_id)
+      link_set_3 = create(:link_set, content_id: source_edition_3.content_id)
+      create(:link, link_set: link_set_1, target_content_id: target_edition.content_id, link_type: "test_link")
+      create(:link, link_set: link_set_2, target_content_id: target_edition.content_id, link_type: "another_link_type")
+      create(:link, link_set: link_set_3, target_content_id: target_edition.content_id, link_type: "test_link")
 
-    source_edition_1 = create(:edition,
-                              links_hash: {
-                                "test_link" => [target_edition.content_id],
-                              })
+      GraphQL::Dataloader.with_dataloading do |dataloader|
+        request = dataloader.with(described_class, parent_object: target_edition, only_current: true).request("test_link")
+
+        expect(request.load).to eq([source_edition_1])
+      end
+    end
 
-    source_edition_2 = create(:edition,
-                              links_hash: {
-                                "test_link" => [target_edition.content_id],
-                              })
+    it "returns the specified reverse edition links for current role appointments only" do
+      target_edition = create(:edition)
 
-    create(:edition,
-           links_hash: {
-             "another_link_type" => [target_edition.content_id],
-           })
+      source_edition_1 = create(:edition,
+                                details: { current: true },
+                                links_hash: {
+                                  "test_link" => [target_edition.content_id],
+                                })
 
-    GraphQL::Dataloader.with_dataloading do |dataloader|
-      request = dataloader.with(described_class, parent_object: target_edition).request("test_link")
+      create(:edition,
+             details: { current: false },
+             links_hash: {
+               "test_link" => [target_edition.content_id],
+             })
 
-      expect(request.load).to eq([source_edition_1, source_edition_2])
+      create(:edition,
+             details: { current: true },
+             links_hash: {
+               "another_link_type" => [target_edition.content_id],
+             })
+
+      GraphQL::Dataloader.with_dataloading do |dataloader|
+        request = dataloader.with(described_class, parent_object: target_edition, only_current: true).request("test_link")
+
+        expect(request.load).to eq([source_edition_1])
+      end
     end
+
+    ## TODO: add a test for retrieving from the right content store
   end
 end