v3: clients can order apps by state

[finishes #173475906]

Co-authored-by: Weyman Fung <wfung@pivotal.io>
Co-authored-by: Merric de Launey <mdelauney@pivotal.io>

Author: weymanf

app/controllers/v3/apps_controller.rb

@@ -49,10 +49,13 @@ def index
     decorators << IncludeSpaceDecorator if IncludeSpaceDecorator.match?(message.include)
     decorators << IncludeOrganizationDecorator if IncludeOrganizationDecorator.match?(message.include)
 
+    page_results = SequelPaginator.new.get_page(dataset, message.try(:pagination_options))
+    handle_order_by_presented_value(page_results)
+
     render status: :ok,
            json: Presenters::V3::PaginatedListPresenter.new(
              presenter: Presenters::V3::AppPresenter,
-             paginated_result: SequelPaginator.new.get_page(dataset, message.try(:pagination_options)),
+             paginated_result: page_results,
              path: '/v3/apps',
              message: message,
              decorators: decorators
@@ -352,6 +355,12 @@ def translate_error(e)
 
   private
 
+  def handle_order_by_presented_value(page_results)
+    if page_results.try(:pagination_options).try(:order_by) == 'desired_state'
+      page_results.pagination_options.order_by = 'state'
+    end
+  end
+
   def deployment_in_progress!
     unprocessable!(
       'Unable to assign current droplet while the app has a deployment in progress. Wait for the deployment to complete or cancel it.'

app/messages/apps_list_message.rb

@@ -23,11 +23,19 @@ class AppsListMessage < MetadataListMessage
     validates :stacks, array: true, allow_nil: true
 
     def valid_order_by_values
-      super + [:name]
+      super + [:name, :state]
     end
 
     def self.from_params(params)
       super(params, %w(names guids organization_guids space_guids stacks include))
     end
+
+    def pagination_options
+      super.tap do |po|
+        if po.order_by == 'state'
+          po.order_by = 'desired_state'
+        end
+      end
+    end
   end
 end

spec/request/apps_spec.rb

@@ -780,6 +780,31 @@
         expect(app_names).to eq(descending)
         expect(parsed_response['pagination']['first']['href']).to include('order_by=-name')
       end
+
+      it 'can order by state' do
+        VCAP::CloudController::AppModel.make(space: space, desired_state: 'STARTED')
+        VCAP::CloudController::AppModel.make(space: space, desired_state: 'STOPPED')
+        VCAP::CloudController::AppModel.make(space: space, desired_state: 'STARTED')
+        VCAP::CloudController::AppModel.make(space: space, desired_state: 'STOPPED')
+        ascending = ['STARTED', 'STARTED', 'STOPPED', 'STOPPED']
+        descending = ascending.reverse
+
+        # ASCENDING
+        get '/v3/apps?order_by=state', nil, user_header
+        expect(last_response.status).to eq(200)
+        parsed_response = MultiJson.load(last_response.body)
+        app_states = parsed_response['resources'].map { |i| i['state'] }
+        expect(app_states).to eq(ascending)
+        expect(parsed_response['pagination']['first']['href']).to include("order_by=#{CGI.escape('+')}state")
+
+        # DESCENDING
+        get '/v3/apps?order_by=-state', nil, user_header
+        expect(last_response.status).to eq(200)
+        parsed_response = MultiJson.load(last_response.body)
+        app_states = parsed_response['resources'].map { |i| i['state'] }
+        expect(app_states).to eq(descending)
+        expect(parsed_response['pagination']['first']['href']).to include('order_by=-state')
+      end
     end
 
     context 'labels' do