**V3** client can filter **feature flags** by **updated_ats**

* client will receive a user friendly error for trying to filter on **created_ats** because this resource does not surface created_at in the endpoint.

[finishes #173720279]

Co-authored-by: Mona Mohebbi <mmohebbi@pivotal.io>
Co-authored-by: Seth Boyles <sboyles@pivotal.io>
Co-authored-by: Sarah Weinstein <sweinstein@pivotal.io>
Co-authored-by: Harsha Nandiwada <hnandiwada@vmware.com>

Author: 4 people

app/controllers/v3/feature_flags_controller.rb

@@ -3,17 +3,14 @@
 require 'messages/feature_flags_update_message'
 require 'actions/feature_flag_update'
 require 'cloud_controller/paging/list_paginator'
+require 'fetchers/feature_flag_list_fetcher'
 
 class FeatureFlagsController < ApplicationController
   def index
     message = FeatureFlagsListMessage.from_params(query_params)
     invalid_param!(message.errors.full_messages) unless message.valid?
 
-    db_feature_flags = FeatureFlag.all
-    dataset = FeatureFlag::DEFAULT_FLAGS.collect do |feature_flag_name, default_enabled_state|
-      db_flag = db_feature_flags.find { |feature_flag| feature_flag.name == feature_flag_name.to_s }
-      db_flag || FeatureFlag.new(name: feature_flag_name, enabled: default_enabled_state)
-    end
+    dataset = FeatureFlagListFetcher.fetch_all(message)
 
     render status: :ok, json: Presenters::V3::PaginatedListPresenter.new(
       presenter: Presenters::V3::FeatureFlagPresenter,

app/fetchers/feature_flag_list_fetcher.rb

@@ -0,0 +1,28 @@
+require 'cloud_controller/paging/sequel_paginator'
+require 'cloud_controller/paging/paginated_result'
+require 'fetchers/label_selector_query_generator'
+require 'fetchers/base_list_fetcher'
+
+module VCAP::CloudController
+  class FeatureFlagListFetcher < BaseListFetcher
+    class << self
+      def fetch_all(message, eager_loaded_associations: [])
+        db_feature_flags = FeatureFlag.dataset
+        if message.updated_ats
+          db_feature_flags = filter(message, db_feature_flags).all
+        else
+          FeatureFlag::DEFAULT_FLAGS.collect do |feature_flag_name, default_enabled_state|
+            db_flag = db_feature_flags.find { |feature_flag| feature_flag.name == feature_flag_name.to_s }
+            db_flag || FeatureFlag.new(name: feature_flag_name, enabled: default_enabled_state)
+          end
+        end
+      end
+
+      private
+
+      def filter(message, dataset)
+        super(message, dataset, FeatureFlag)
+      end
+    end
+  end
+end

app/messages/base_message.rb

@@ -115,6 +115,14 @@ def validate(record)
       end
     end
 
+    class DisallowCreatedAtsParamValidator < ActiveModel::Validator
+      def validate(record)
+        if record.requested?(:created_ats)
+          record.errors[:base] << "Filtering by 'created_ats' is not allowed on this resource."
+        end
+      end
+    end
+
     class IncludeParamValidator < ActiveModel::Validator
       def validate(record)
         if record.requested?(:include)

app/messages/feature_flags_list_message.rb

@@ -3,6 +3,7 @@
 module VCAP::CloudController
   class FeatureFlagsListMessage < ListMessage
     validates_with NoAdditionalParamsValidator
+    validates_with DisallowCreatedAtsParamValidator
 
     def self.from_params(params)
       super(params, [])

spec/request/feature_flags_spec.rb

@@ -14,6 +14,39 @@
       flag_names_in_response = parsed_response['resources'].map { |flag| flag['name'] }
       expect(flag_names_in_response).to eq(flag_names_sorted.map(&:to_s))
     end
+
+    context 'filtering timestamps on update' do
+      # before must occur before the let! otherwise the resources will be created with
+      # update_on_create: true
+      before do
+        VCAP::CloudController::FeatureFlag.plugin :timestamps, update_on_create: false
+      end
+
+      let!(:resource_1) { VCAP::CloudController::FeatureFlag.make(name: 'set_roles_by_username', updated_at: '2020-05-26T18:47:01Z') }
+      let!(:resource_2) { VCAP::CloudController::FeatureFlag.make(name: 'task_creation', updated_at: '2020-05-26T18:47:02Z') }
+      let!(:resource_3) { VCAP::CloudController::FeatureFlag.make(name: 'user_org_creation', updated_at: '2020-05-26T18:47:03Z') }
+      let!(:resource_4) { VCAP::CloudController::FeatureFlag.make(name: 'unset_roles_by_username', updated_at: '2020-05-26T18:47:04Z') }
+
+      after do
+        VCAP::CloudController::FeatureFlag.plugin :timestamps, update_on_create: true
+      end
+
+      it 'filters' do
+        get '/v3/feature_flags?updated_ats[gt]=2020-05-26T18:47:02Z', nil, admin_headers
+
+        expect(last_response).to have_status_code(200)
+        expect(parsed_response['resources'].map { |r| r['name'] }).to contain_exactly('user_org_creation', 'unset_roles_by_username')
+      end
+    end
+
+    context 'filtering timestamps on created_ats' do
+      it 'filters' do
+        get '/v3/feature_flags?created_ats[gt]=2020-05-26T18:47:04Z', nil, admin_headers
+
+        expect(last_response).to have_status_code(400)
+        expect(last_response).to have_error_message("The query parameter is invalid: Filtering by 'created_ats' is not allowed on this resource.")
+      end
+    end
   end
 
   describe 'GET /v3/feature_flags/:name' do

spec/unit/fetchers/feature_flag_list_fetcher_spec.rb

@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+module VCAP::CloudController
+  RSpec.describe FeatureFlagListFetcher do
+    subject(:fetcher) { FeatureFlagListFetcher }
+    let(:message) { FeatureFlagsListMessage.from_params(filters) }
+    describe '#fetch_all' do
+      let(:filters) { {} }
+
+      before do
+        VCAP::CloudController::FeatureFlag.plugin :timestamps, update_on_create: false
+      end
+
+      let!(:resource_1) { VCAP::CloudController::FeatureFlag.make(name: 'set_roles_by_username', updated_at: '2020-05-26T18:47:01Z') }
+      let!(:resource_2) { VCAP::CloudController::FeatureFlag.make(name: 'task_creation', updated_at: '2020-05-26T18:47:02Z') }
+      let!(:resource_3) { VCAP::CloudController::FeatureFlag.make(name: 'user_org_creation', updated_at: '2020-05-26T18:47:03Z') }
+      let!(:resource_4) { VCAP::CloudController::FeatureFlag.make(name: 'unset_roles_by_username', updated_at: '2020-05-26T18:47:04Z') }
+
+      after do
+        VCAP::CloudController::FeatureFlag.plugin :timestamps, update_on_create: true
+      end
+
+      context 'when not filtering' do
+        it 'returns an array of all FeatureFlags' do
+          flag_names = VCAP::CloudController::FeatureFlag::DEFAULT_FLAGS.keys.sort.map(&:to_s)
+          expect(subject.fetch_all(message).map(&:name)).to contain_exactly(*flag_names)
+        end
+      end
+
+      context 'when filtering on updated_ats' do
+        let(:filters) {
+          { updated_ats: { gt: '2020-05-26T18:47:02Z' } }
+        }
+        it 'it only returns records that have been updated in the time range' do
+          expect(subject.fetch_all(message).map(&:name)).to contain_exactly('unset_roles_by_username', 'user_org_creation')
+        end
+      end
+    end
+  end
+end

spec/unit/messages/feature_flags_list_message_spec.rb

@@ -61,6 +61,12 @@ module VCAP::CloudController
         expect(message).to be_invalid
         expect(message.errors[:order_by].length).to eq 1
       end
+
+      it 'validates that created_ats is invalid' do
+        message = FeatureFlagsListMessage.from_params({ created_ats: 'created_at' })
+        expect(message).to be_invalid
+        expect(message.errors[:base][0]).to eq "Filtering by 'created_ats' is not allowed on this resource."
+      end
     end
   end
 end