Use GraphQL for rendering news articles

This retrieves the content from Publishing API, instead of Content
Store, using a GraphQL query.

Note this has been done in the way that reduces the number of changes
needed in this application. As a result, we have introduced a small
"hack" to return the data in `GdsApi::Response` format but with this app
rewriting the hash keys to make them all underscore based.

app/controllers/content_items_controller.rb

@@ -136,16 +136,42 @@ def set_guide_draft_access_token
     @content_item.draft_access_token = params[:token]
   end
 
+  class GdsApi::Response
+    def update_response_body
+      updated_response = JSON.parse(@http_response.body).dig("data", "edition").deep_transform_keys(&:underscore)
+      @http_response = RestClient::Response.create(
+        updated_response.to_json,
+        @http_response.net_http_res,
+        @http_response.request,
+      )
+    end
+  end
+
   def load_content_item
+    ## TODO: how do we know this is a news article without content store telling us first??
     content_item = Services.content_store.content_item(content_item_path)
 
-    content_item["links"]["ordered_related_items"] = ordered_related_items(content_item["links"]) if content_item["links"]
-
-    @content_item = PresenterBuilder.new(
-      content_item,
-      content_item_path,
-      view_context,
-    ).presenter
+    @content_item = if content_item["schema_name"] == "news_article" && (Features.graphql_feature_enabled? || params.include?(:graphql))
+                      graphql_response = Services
+                        .publishing_api
+                        .graphql_query(Graphql::NewsArticleQuery.new(content_item_path).query)
+
+                      graphql_response.update_response_body
+
+                      PresenterBuilder.new(
+                        graphql_response,
+                        content_item_path,
+                        view_context,
+                      ).presenter
+                    else
+                      content_item["links"]["ordered_related_items"] = ordered_related_items(content_item["links"]) if content_item["links"]
+
+                      PresenterBuilder.new(
+                        content_item,
+                        content_item_path,
+                        view_context,
+                      ).presenter
+                    end
   end
 
   def ordered_related_items(links)

app/queries/graphql/news_article_query.rb

@@ -0,0 +1,75 @@
+class Graphql::NewsArticleQuery
+  def initialize(base_path)
+    @base_path = base_path
+  end
+
+  def query
+    <<-QUERY
+        {
+          edition(
+            basePath: "#{@base_path}",
+            contentStore: "live",
+          ) {
+            ... on NewsArticle {
+              basePath
+              description
+              details
+              documentType
+              firstPublishedAt
+              links {
+                availableTranslations {
+                  basePath
+                  locale
+                }
+                government {
+                  details {
+                    current
+                  }
+                  title
+                }
+                organisations {
+                  basePath
+                  contentId
+                  title
+                }
+                people {
+                  basePath
+                  contentId
+                  title
+                }
+                taxons {
+                  basePath
+                  contentId
+                  documentType
+                  phase
+                  title
+                  links {
+                    parentTaxons {
+                      basePath
+                      contentId
+                      documentType
+                      phase
+                      title
+                    }
+                  }
+                }
+                topicalEvents {
+                  basePath
+                  contentId
+                  title
+                }
+                worldLocations {
+                  basePath
+                  contentId
+                  title
+                }
+              }
+              locale
+              schemaName
+              title
+            }
+          }
+        }
+    QUERY
+  end
+end

test/controllers/content_items_controller_test.rb

@@ -1,7 +1,9 @@
 require "test_helper"
+require "gds_api/test_helpers/publishing_api"
 
 class ContentItemsControllerTest < ActionController::TestCase
   include GdsApi::TestHelpers::ContentStore
+  include GdsApi::TestHelpers::PublishingApi
   include GovukAbTesting::MinitestHelpers
 
   test "routing handles paths with no format or locale" do
@@ -124,6 +126,42 @@ class ContentItemsControllerTest < ActionController::TestCase
     assert_response :not_acceptable
   end
 
+  test "with the GraphQL feature flag enabled gets item from GraphQL if it is a news article" do
+    Features.stubs(:graphql_feature_enabled?).returns(true)
+
+    content_item = content_store_has_schema_example("news_article", "news_article")
+    base_path = content_item["base_path"]
+
+    graphql_fixture = fetch_graphql_fixture("news_article")
+    stub_publishing_api_graphql_query(Graphql::NewsArticleQuery.new(base_path).query, graphql_fixture)
+
+    get :show,
+        params: {
+          path: path_for(content_item),
+        }
+
+    assert_requested :post, "#{PUBLISHING_API_ENDPOINT}/graphql",
+                     body: { query: Graphql::NewsArticleQuery.new(base_path).query },
+                     times: 1
+
+    assert_response :success
+  end
+
+  test "with the GraphQL feature flag enabled does not get item from GraphQL if it is not a news article" do
+    Features.stubs(:graphql_feature_enabled?).returns(true)
+
+    content_item = content_store_has_schema_example("case_study", "case_study")
+
+    get :show,
+        params: {
+          path: path_for(content_item),
+        }
+
+    assert_not_requested :post, "#{PUBLISHING_API_ENDPOINT}/graphql"
+
+    assert_response :success
+  end
+
   test "gets item from content store" do
     content_item = content_store_has_schema_example("case_study", "case_study")
 

test/fixtures/graphql/news_article.json

@@ -0,0 +1,72 @@
+{
+  "data": {
+    "edition": {
+      "basePath": "/government/news/announcement",
+      "description": "Summary of the news",
+      "details": {
+        "body": "Some text",
+        "political": "true"
+      },
+      "documentType": "news_story",
+      "firstPublishedAt": "2016-12-25T01:02:03+00:00",
+      "links": {
+        "availableTranslations": [
+          {
+            "basePath": "/government/news/announcement",
+            "locale": "en"
+          }
+        ],
+        "government": [
+          {
+            "details": {
+              "current": false
+            },
+            "title": "A government"
+          }
+        ],
+        "organisations": [
+          {
+            "basePath": "/organisation-1",
+            "title": "An organisation"
+          }
+        ],
+        "people": [
+          {
+            "basePath": "/person-1",
+            "title": "A person"
+          }
+        ],
+        "taxons": [
+          {
+            "basePath": "/taxon-1",
+            "contentId": "8fa1fa2f-bcce-4cde-98fb-308514c35c63",
+            "title": "Taxon 1",
+            "links": {
+              "parentTaxons": [
+                {
+                  "basePath": "/taxon-2",
+                  "contentId": "9de167ce-6c4f-40b1-a45e-e3160d75556e",
+                  "title": "Taxon 2"
+                }
+              ]
+            }
+          }
+        ],
+        "topicalEvents": [
+          {
+            "basePath": "/topical-event-1",
+            "title": "A topical event"
+          }
+        ],
+        "worldLocations": [
+          {
+            "basePath": "/world-location-1",
+            "title": "A world location"
+          }
+        ]
+      },
+      "schemaName": "news_article",
+      "title": "Generic news article"
+    }
+  }
+}

test/presenter_test_helper.rb

@@ -28,3 +28,17 @@ def schema_item(type = schema_name, schema = schema_name)
     govuk_content_schema_example(schema, type)
   end
 end
+
+class GraphqlPresenterTestCase < PresenterTestCase
+  def create_presenter(presenter_class,
+                       content_item: fetch_graphql_fixture("news_article"),
+                       requested_path: "/test-content-item",
+                       view_context: ApplicationController.new.view_context)
+    presenter_class.new(content_item, requested_path, view_context)
+  end
+
+  def presented_item(type = schema_name, overrides = {})
+    example = fetch_graphql_fixture(type).dig("data", "edition").deep_transform_keys(&:underscore)
+    present_example(example.merge(overrides))
+  end
+end

test/presenters/news_article_graphql_presenter_test.rb

@@ -0,0 +1,33 @@
+require "presenter_test_helper"
+
+class NewsArticleGraphqlPresenterTest
+  class NewsArticleGraphqlPresenterTestCase < GraphqlPresenterTestCase
+    attr_accessor :example_schema_name
+
+    def schema_name
+      "news_article"
+    end
+  end
+
+  class PresentedNewsArticleGraphqlTest < NewsArticleGraphqlPresenterTestCase
+    test "presents a description" do
+      assert_equal "Summary of the news", presented_item.description
+    end
+
+    test "presents a body" do
+      assert_equal "Some text", presented_item.body
+    end
+
+    test "presents a readable first published date" do
+      assert_equal "25 December 2016", presented_item.published
+    end
+
+    test "presents the locale" do
+      assert_equal "en", presented_item.locale
+    end
+
+    test "presents historically political" do
+      assert presented_item.historically_political?
+    end
+  end
+end

test/test_helper.rb

@@ -279,3 +279,10 @@ def single_page_notification_button_ga4_tracking(index_link, section)
     }
   end
 end
+
+def fetch_graphql_fixture(filename)
+  json = File.read(
+    Rails.root.join("test", "fixtures", "graphql", "#{filename}.json"),
+  )
+  JSON.parse(json)
+end