use represent_concise instead of separate entity

app/controllers/projects/deployments_controller.rb

@@ -7,7 +7,7 @@ class Projects::DeploymentsController < Projects::ApplicationController
     deployments = deployments.where('created_at > ?', params[:after].to_time) if params[:after]&.to_time
 
     render json: { deployments: DeploymentSerializer.new(user: @current_user, project: project)
-                                  .represent(deployments) }
+                                  .represent_concise(deployments) }
   end
 
   private

app/serializers/deployment_entity.rb

@@ -9,9 +9,21 @@ class DeploymentEntity < Grape::Entity
     expose :name do |deployment|
       deployment.ref
     end
+
+    expose :ref_path do |deployment|
+      namespace_project_tree_path(
+        deployment.project.namespace,
+        deployment.project,
+        id: deployment.ref)
+    end
   end
 
   expose :created_at
   expose :tag
   expose :last?
+
+  expose :user, using: UserEntity
+  expose :commit, using: CommitEntity
+  expose :deployable, using: BuildEntity
+  expose :manual_actions, using: BuildEntity
 end

app/serializers/deployment_entity_detailed.rb

-class DeploymentEntityDetailed < DeploymentEntity
-  expose :ref do
-    expose :ref_path do |deployment|
-      namespace_project_tree_path(
-        deployment.project.namespace,
-        deployment.project,
-        id: deployment.ref)
-    end
-  end
-
-  expose :user, using: UserEntity
-  expose :commit, using: CommitEntity
-  expose :deployable, using: BuildEntity
-  expose :manual_actions, using: BuildEntity
-end

app/serializers/deployment_serializer.rb

 class DeploymentSerializer < BaseSerializer
   entity DeploymentEntity
+
+  def represent_concise(resource, opts = {})
+    opts[:only] = [:iid, :id, :sha, :created_at, :tag, :last?, :id, ref: [:name]]
+    represent(resource, opts)
+  end
 end

spec/serializers/deployment_entity_detailed_spec.rb

-require 'spec_helper'
-
-describe DeploymentEntityDetailed do
-  let(:user) { create(:user) }
-  let(:request) { double('request') }
-  let(:deployment) { create(:deployment) }
-  let(:entity) { described_class.new(deployment, request: request) }
-  subject { entity.as_json }
-
-  before do
-    allow(request).to receive(:user).and_return(user)
-  end
-
-  it 'exposes internal deployment id'  do
-    expect(subject).to include(:iid)
-  end
-
-  it 'exposes nested information about branch' do
-    expect(subject[:ref][:name]).to eq 'master'
-    expect(subject[:ref][:ref_path]).not_to be_empty
-  end
-
-  it 'exposes creation date' do
-    expect(subject).to include(:created_at)
-  end
-end