Allow current=true filter on GET /v3/droplets to return only current droplets across all apps

app/fetchers/droplet_list_fetcher.rb

@@ -32,14 +32,19 @@ def droplet_dataset(eager_loaded_associations, dataset=DropletModel.dataset)
       end
 
       def filter(message, app, space_guids, dataset)
-        if message.requested?(:current) && app
-          dataset = dataset.extension(:null_dataset)
-          return dataset.nullify unless app.droplet
-
-          dataset = dataset.where(guid: app.droplet_guid)
+        if message.requested?(:current)
+          if app
+            dataset = dataset.extension(:null_dataset)
+            return dataset.nullify unless app.droplet
+
+            dataset = dataset.where(guid: app.droplet_guid)
+          else
+            dataset = dataset.select_all(DropletModel.table_name).
+                      join_table(:inner, AppModel.table_name, { droplet_guid: Sequel[DropletModel.table_name][:guid] }, { table_alias: :apps_current })
+          end
         end
 
-        dataset = dataset.where(app_guid: message.app_guids) if message.requested?(:app_guids)
+        dataset = dataset.where(Sequel[DropletModel.table_name][:app_guid] => message.app_guids) if message.requested?(:app_guids)
 
         dataset = dataset.where(state: message.states) if message.requested?(:states)
 

app/messages/droplets_list_message.rb

@@ -18,9 +18,9 @@ class DropletsListMessage < MetadataListMessage
     validates :states, array: true, allow_nil: true
     validates :space_guids, array: true, allow_nil: true
     validates :organization_guids, array: true, allow_nil: true
-    validates :current, inclusion: { in: ['true'], message: 'only accepts the value \'true\'' }, allow_nil: true, if: -> { app_guid.present? }
+    validates :current, inclusion: { in: ['true'], message: 'only accepts the value \'true\'' }, allow_nil: true
     validate :app_nested_request, if: -> { app_guid.present? }
-    validate :not_app_nested_request, unless: -> { app_guid.present? }
+    validate :package_nested_request, if: -> { package_guid.present? }
 
     def to_param_hash
       super(exclude: %i[app_guid package_guid])
@@ -32,18 +32,18 @@ def self.from_params(params)
 
     private
 
-    def not_app_nested_request
-      invalid_attributes = []
-      invalid_attributes << :current if current
-      errors.add(:base, "Unknown query parameter(s): '#{invalid_attributes.join("', '")}'") if invalid_attributes.present?
-    end
-
     def app_nested_request
       invalid_attributes = []
       invalid_attributes << :app_guids if app_guids
       invalid_attributes << :organization_guids if organization_guids
       invalid_attributes << :space_guids if space_guids
       errors.add(:base, "Unknown query parameter(s): '#{invalid_attributes.join("', '")}'") if invalid_attributes.present?
     end
+
+    def package_nested_request
+      invalid_attributes = []
+      invalid_attributes << :current if current
+      errors.add(:base, "Unknown query parameter(s): '#{invalid_attributes.join("', '")}'") if invalid_attributes.present?
+    end
   end
 end

docs/v3/source/includes/resources/droplets/_list.md.erb

@@ -33,6 +33,7 @@ Name | Type | Description
 **guids** | _list of strings_ | Comma-delimited list of droplet guids to filter by
 **states** | _list of strings_ | Comma-delimited list of droplet states to filter by
 **app_guids** | _list of strings_ | Comma-delimited list of app guids to filter by
+**current** | _boolean_ | If true, only include the current droplet for each app
 **space_guids** | _list of strings_ | Comma-delimited list of space guids to filter by
 **organization_guids** | _list of strings_ | Comma-delimited list of organization guids to filter by
 **page** | _integer_ | Page to display; valid values are integers >= 1

spec/request/droplets_spec.rb

@@ -659,6 +659,7 @@
           space_guids
           app_guids
           organization_guids
+          current
         ]
       end
       let(:params) do
@@ -668,7 +669,6 @@
           order_by: 'updated_at',
           guids: 'foo,bar',
           app_guid: app_model.guid,
-          current: true,
           package_guid: package_model.guid,
           states: %w[test foo],
           label_selector: 'foo,bar',
@@ -941,6 +941,50 @@
         returned_guids = parsed_response['resources'].pluck('guid')
         expect(returned_guids).to contain_exactly(droplet1.guid, droplet2.guid, droplet3.guid)
       end
+
+      it 'filters by current=true as admin' do
+        current_droplet_app1 = create(:droplet_model, app: app_model, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        current_droplet_app2 = create(:droplet_model, app: app_model2, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        current_droplet_app3 = create(:droplet_model, app: app_model3, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        app_model.update(droplet: current_droplet_app1)
+        app_model2.update(droplet: current_droplet_app2)
+        app_model3.update(droplet: current_droplet_app3)
+
+        get '/v3/droplets?current=true', nil, admin_headers
+
+        expect(last_response.status).to eq(200)
+        returned_guids = parsed_response['resources'].pluck('guid')
+        expect(returned_guids).to contain_exactly(current_droplet_app1.guid, current_droplet_app2.guid, current_droplet_app3.guid)
+      end
+
+      it 'filters by current=true as a non-admin developer, returning only current droplets in readable spaces' do
+        current_droplet_app1 = create(:droplet_model, app: app_model, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        current_droplet_app2 = create(:droplet_model, app: app_model2, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        current_droplet_app3 = create(:droplet_model, app: app_model3, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        app_model.update(droplet: current_droplet_app1)
+        app_model2.update(droplet: current_droplet_app2)
+        app_model3.update(droplet: current_droplet_app3)
+
+        get '/v3/droplets?current=true', nil, developer_headers
+
+        expect(last_response.status).to eq(200)
+        returned_guids = parsed_response['resources'].pluck('guid')
+        expect(returned_guids).to contain_exactly(current_droplet_app1.guid, current_droplet_app2.guid)
+        expect(returned_guids).not_to include(current_droplet_app3.guid)
+      end
+
+      it 'filters by current=true combined with app_guids' do
+        current_droplet_app1 = create(:droplet_model, app: app_model, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        current_droplet_app2 = create(:droplet_model, app: app_model2, state: VCAP::CloudController::DropletModel::STAGED_STATE)
+        app_model.update(droplet: current_droplet_app1)
+        app_model2.update(droplet: current_droplet_app2)
+
+        get "/v3/droplets?current=true&app_guids=#{app_model.guid}", nil, developer_headers
+
+        expect(last_response.status).to eq(200)
+        returned_guids = parsed_response['resources'].pluck('guid')
+        expect(returned_guids).to contain_exactly(current_droplet_app1.guid)
+      end
     end
 
     context 'label_selector' do

spec/unit/fetchers/droplet_list_fetcher_spec.rb

@@ -125,6 +125,76 @@ module VCAP::CloudController
           expect(results).to contain_exactly(staged_droplet_for_app1)
         end
       end
+
+      context 'filtering by current=true' do
+        let(:filters) { { current: 'true' } }
+
+        context 'when some apps have a current droplet set' do
+          before do
+            app1.update(droplet: staged_droplet_for_app1)
+            app2.update(droplet: staged_droplet_for_app2)
+          end
+
+          it 'returns only current droplets' do
+            results = fetcher.fetch_all(message).all
+            expect(results).to contain_exactly(staged_droplet_for_app1, staged_droplet_for_app2)
+          end
+
+          it 'does not return non-current droplets' do
+            results = fetcher.fetch_all(message).all
+            expect(results).not_to include(failed_droplet_for_app1)
+          end
+        end
+
+        context 'when no apps have a current droplet set' do
+          it 'returns an empty list' do
+            results = fetcher.fetch_all(message).all
+            expect(results).to be_empty
+          end
+        end
+
+        context 'when combined with app_guids filter' do
+          before do
+            app1.update(droplet: staged_droplet_for_app1)
+            app2.update(droplet: staged_droplet_for_app2)
+          end
+
+          let(:filters) { { current: 'true', app_guids: [app1.guid] } }
+
+          it 'returns only the current droplet for the specified app' do
+            results = fetcher.fetch_all(message).all
+            expect(results).to contain_exactly(staged_droplet_for_app1)
+          end
+        end
+
+        context 'when combined with space_guids filter' do
+          before do
+            app1.update(droplet: staged_droplet_for_app1)
+            app2.update(droplet: staged_droplet_for_app2)
+          end
+
+          let(:filters) { { current: 'true', space_guids: [app1.space.guid] } }
+
+          it 'returns only current droplets in the specified space' do
+            results = fetcher.fetch_all(message).all
+            expect(results).to contain_exactly(staged_droplet_for_app1)
+          end
+        end
+
+        context 'when combined with organization_guids filter' do
+          before do
+            app1.update(droplet: staged_droplet_for_app1)
+            app2.update(droplet: staged_droplet_for_app2)
+          end
+
+          let(:filters) { { current: 'true', organization_guids: [app1.organization.guid] } }
+
+          it 'returns only current droplets in the specified organization' do
+            results = fetcher.fetch_all(message).all
+            expect(results).to contain_exactly(staged_droplet_for_app1)
+          end
+        end
+      end
     end
 
     describe '#fetch_for_spaces' do

spec/unit/messages/droplets_list_message_spec.rb

@@ -125,8 +125,23 @@ module VCAP::CloudController
 
         context 'when the query is not nested under an app' do
           context 'when the request contains current field' do
-            it 'is invalid' do
+            it 'is valid' do
               message = DropletsListMessage.from_params({ current: 'true' })
+              expect(message).to be_valid
+            end
+
+            it 'validates current must be true' do
+              message = DropletsListMessage.from_params({ current: 'false' })
+              expect(message).not_to be_valid
+              expect(message.errors[:current]).to include("only accepts the value 'true'")
+            end
+          end
+        end
+
+        context 'when the query is nested under a package' do
+          context 'when the request contains current field' do
+            it 'is invalid' do
+              message = DropletsListMessage.from_params({ package_guid: 'some-package-guid', current: 'true' })
               expect(message).not_to be_valid
               expect(message.errors[:base][0]).to include("Unknown query parameter(s): 'current'")
             end