Get guid,name of service broker in service plan single request

[#172379944](https://www.pivotaltracker.com/story/show/172379944)

Author: pivotal-marcela-campo

app/controllers/v3/service_plans_controller.rb

@@ -3,6 +3,7 @@
 require 'fetchers/service_plan_fetcher'
 require 'controllers/v3/mixins/service_permissions'
 require 'messages/service_plans_list_message'
+require 'messages/service_plans_show_message'
 require 'actions/service_plan_delete'
 require 'messages/metadata_update_message'
 require 'actions/transactional_metadata_update'
@@ -16,11 +17,17 @@ class ServicePlansController < ApplicationController
   def show
     not_authenticated! if user_cannot_see_marketplace?
 
+    message = ServicePlansShowMessage.from_params(query_params)
+    invalid_param!(message.errors.full_messages) unless message.valid?
+
     service_plan = ServicePlanFetcher.fetch(hashed_params[:guid])
     service_plan_not_found! if service_plan.nil?
     service_plan_not_found! unless visible_to_current_user?(plan: service_plan)
 
-    presenter = Presenters::V3::ServicePlanPresenter.new(service_plan)
+    decorators = []
+    decorators << FieldServicePlanServiceBrokerDecorator.new(message.fields) if FieldServicePlanServiceBrokerDecorator.match?(message.fields)
+
+    presenter = Presenters::V3::ServicePlanPresenter.new(service_plan, decorators: decorators)
     render status: :ok, json: presenter.to_json
   end
 

app/messages/service_plans_show_message.rb

@@ -0,0 +1,16 @@
+module VCAP::CloudController
+  class ServicePlansShowMessage < BaseMessage
+    register_allowed_keys [:fields]
+
+    validates_with NoAdditionalParamsValidator
+    validates :fields, allow_nil: true, fields: {
+      allowed: {
+        'service_offering.service_broker' => ['guid', 'name']
+      }
+    }
+
+    def self.from_params(params)
+      super(params, [], fields: %w(fields))
+    end
+  end
+end

app/presenters/v3/service_plan_presenter.rb

@@ -8,7 +8,7 @@ class ServicePlanPresenter < BasePresenter
         include VCAP::CloudController::Presenters::Mixins::MetadataPresentationHelpers
 
         def to_hash
-          {
+          hash = {
             guid: service_plan.guid,
             created_at: service_plan.created_at,
             updated_at: service_plan.updated_at,
@@ -43,6 +43,8 @@ def to_hash
             },
             links: links
           }
+
+          @decorators.reduce(hash) { |memo, d| d.decorate(memo, [service_plan]) }
         end
 
         private

docs/v3/source/includes/experimental_resources/service_plans/_get.md.erb

@@ -26,6 +26,19 @@ This endpoint retrieves the service plan by GUID.
 #### Definition
 `GET /v3/service_plans/:guid`
 
+#### Query parameters
+
+Name | Type | Description
+---- | ---- | ------------
+**fields** | [_fields parameter_](#fields-parameter) | [_Allowed values_](#service-plan-fields)
+
+##### Service Plan Fields
+
+Resource            | Allowed Keys
+------------------- | ----
+service_offering.service_broker| `guid`, `name`
+
+
 #### Permitted roles
  |
 --- | ---

spec/request/service_plans_spec.rb

@@ -127,6 +127,20 @@
         expect(parsed_response).to eq(link_response)
       end
     end
+
+    describe 'fields' do
+      let!(:service_plan) { VCAP::CloudController::ServicePlan.make }
+      let(:guid) { service_plan.guid }
+
+      it 'can include service broker name and guid' do
+        get "/v3/service_plans/#{guid}?fields[service_offering.service_broker]=name,guid", nil, admin_headers
+        expect(last_response).to have_status_code(200)
+
+        expect(parsed_response['included']['service_brokers']).to have(1).elements
+        expect(parsed_response['included']['service_brokers'][0]['guid']).to eq(service_plan.service.service_broker.guid)
+        expect(parsed_response['included']['service_brokers'][0]['name']).to eq(service_plan.service.service_broker.name)
+      end
+    end
   end
 
   describe 'GET /v3/service_plans' do

spec/unit/messages/service_plans_show_message_spec.rb

@@ -0,0 +1,58 @@
+require 'spec_helper'
+require 'messages/service_plans_show_message'
+require 'field_message_spec_shared_examples'
+
+module VCAP::CloudController
+  RSpec.describe ServicePlansShowMessage do
+    describe '.from_params' do
+      let(:params) do
+        {
+          'fields' => { 'service_offering.service_broker' => 'guid,name' },
+        }.with_indifferent_access
+      end
+
+      it 'returns the correct ServicePlansShowMessage' do
+        message = described_class.from_params(params)
+
+        expect(message).to be_valid
+        expect(message).to be_a(described_class)
+        expect(message.fields).to match({ 'service_offering.service_broker': ['guid', 'name'] })
+      end
+
+      it 'converts requested keys to symbols' do
+        message = described_class.from_params(params)
+        expect(message.requested?(:fields)).to be_truthy
+      end
+
+      it 'accepts an empty set' do
+        message = described_class.from_params({})
+        expect(message).to be_valid
+      end
+
+      it 'does not accept arbitrary parameters' do
+        message = described_class.from_params({ foobar: 'pants' }.with_indifferent_access)
+
+        expect(message).not_to be_valid
+        expect(message.errors[:base][0]).to include("Unknown query parameter(s): 'foobar'")
+      end
+
+      context 'fields' do
+        it 'validates `fields` is a hash' do
+          message = described_class.from_params({ 'fields' => 'foo' }.with_indifferent_access)
+          expect(message).not_to be_valid
+          expect(message.errors[:fields][0]).to include('must be an object')
+        end
+
+        it_behaves_like 'field query parameter', 'service_offering.service_broker', 'guid,name'
+
+        it 'does not accept fields resources that are not allowed' do
+          message = described_class.from_params({ 'fields' => { 'space.foo': 'name' } })
+          expect(message).not_to be_valid
+          expect(message.errors[:fields]).to include(
+            "[space.foo] valid resources are: 'service_offering.service_broker'"
+          )
+        end
+      end
+    end
+  end
+end

spec/unit/presenters/v3/service_plan_presenter_spec.rb

@@ -234,5 +234,22 @@
         })
       end
     end
+
+    context 'when a decorator is provided' do
+      class FakeDecorator
+        def self.decorate(hash, resources)
+          hash[:included] = { resource: { guid: resources[0].guid } }
+          hash
+        end
+      end
+
+      let(:result) { described_class.new(service_plan, decorators: [FakeDecorator]).to_hash.deep_symbolize_keys }
+
+      let(:service_plan) { VCAP::CloudController::ServicePlan.make }
+
+      it 'uses the decorator' do
+        expect(result[:included]).to match({ resource: { guid: service_plan.guid } })
+      end
+    end
   end
 end