Make pagination optional for issuables

On epics roadmap page we list all epics in the given time frame
without pagination (at least for the first iteration), in this
case it would be nice to use the existing issuables index logic
except pagination (see MR gitlab-ee!4281). For this reason this
patch allows to easily disable pagination.

Related gitlab-ee!4281

2 files changed, 27 insertions, 5 deletions

diff --git a/app/controllers/concerns/issuable_collections.rb b/app/controllers/concerns/issuable_collections.rb
index b25e753a5ad..2fa0f98e344 100644
--- a/app/controllers/concerns/issuable_collections.rb
+++ b/app/controllers/concerns/issuable_collections.rb
@@ -12,11 +12,9 @@ module IssuableCollections
 
   # rubocop:disable Gitlab/ModuleWithInstanceVariables
   def set_issuables_index
-    @issuables          = issuables_collection
-    @issuables          = @issuables.page(params[:page])
-    @issuable_meta_data = issuable_meta_data(@issuables, collection_type)
-    @total_pages        = issuable_page_count
+    @issuables = issuables_collection
 
+    set_pagination
     return if redirect_out_of_range(@total_pages)
 
     if params[:label_name].present?
@@ -35,14 +33,26 @@ module IssuableCollections
       @users.push(author) if author
     end
   end
+
+  def set_pagination
+    return if pagination_disabled?
+
+    @issuables          = @issuables.page(params[:page])
+    @issuable_meta_data = issuable_meta_data(@issuables, collection_type)
+    @total_pages        = issuable_page_count
+  end
   # rubocop:enable Gitlab/ModuleWithInstanceVariables
 
+  def pagination_disabled?
+    false
+  end
+
   def issuables_collection
     finder.execute.preload(preload_for_collection)
   end
 
   def redirect_out_of_range(total_pages)
-    return false if total_pages.zero?
+    return false if total_pages.nil? || total_pages.zero?
 
     out_of_range = @issuables.current_page > total_pages # rubocop:disable Gitlab/ModuleWithInstanceVariables
 
diff --git a/spec/controllers/projects/issues_controller_spec.rb b/spec/controllers/projects/issues_controller_spec.rb
index 4a2998b4ccd..9656e7f7e74 100644
--- a/spec/controllers/projects/issues_controller_spec.rb
+++ b/spec/controllers/projects/issues_controller_spec.rb
@@ -102,6 +102,18 @@ describe Projects::IssuesController do
 
         expect(response).to redirect_to(namespace_project_issues_path(page: last_page, state: controller.params[:state], scope: controller.params[:scope]))
       end
+
+      it 'does not use pagination if disabled' do
+        allow(controller).to receive(:pagination_disabled?).and_return(true)
+
+        get :index,
+          namespace_id: project.namespace.to_param,
+          project_id: project,
+          page: (last_page + 1).to_param
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(assigns(:issues).size).to eq(2)
+      end
     end
   end