Add first? deployment check to see if a deployment is a first one for given environment

app/models/deployment.rb

@@ -30,6 +30,10 @@ class Deployment < ActiveRecord::Base
     self == environment.last_deployment
   end
 
+  def first?
+    self == environment.first_deployment
+  end
+
   def create_ref
     project.repository.create_ref(ref, ref_path)
   end

app/models/environment.rb

@@ -9,6 +9,7 @@ class Environment < ActiveRecord::Base
   has_many :deployments, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 
   has_one :last_deployment, -> { order('deployments.id DESC') }, class_name: 'Deployment'
+  has_one :first_deployment, -> { order('deployments.id ASC') }, class_name: 'Deployment'
 
   before_validation :nullify_external_url
   before_validation :generate_slug, if: ->(env) { env.slug.blank? }

app/serializers/deployment_entity.rb

@@ -18,6 +18,7 @@ class DeploymentEntity < Grape::Entity
   expose :created_at
   expose :tag
   expose :last?
+  expose :first?
 
   expose :user, using: UserEntity
   expose :commit, using: CommitEntity

app/serializers/deployment_serializer.rb

@@ -2,7 +2,7 @@ class DeploymentSerializer < BaseSerializer
   entity DeploymentEntity
 
   def represent_concise(resource, opts = {})
-    opts[:only] = [:iid, :id, :sha, :created_at, :tag, :last?, :id, ref: [:name]]
+    opts[:only] = [:iid, :id, :sha, :created_at, :tag, :last?, :first?, :id, ref: [:name]]
     represent(resource, opts)
   end
 end

spec/fixtures/api/schemas/deployments.json

@@ -17,6 +17,9 @@
           "last?": {
             "type": "boolean"
           },
+          "first?": {
+            "type": "boolean"
+          },
           "ref": {
             "additionalProperties": false,
             "properties": {
@@ -42,6 +45,7 @@
           "iid",
           "tag",
           "last?",
+          "first?",
           "ref",
           "id"
         ],

spec/models/deployment_spec.rb

@@ -29,6 +29,38 @@ describe Deployment do
     end
   end
 
+  describe '#last?' do
+    let(:environment) { create(:environment) }
+    let!(:first_deployment) { create(:deployment, environment: environment) }
+    let!(:middle_deployment) { create(:deployment, environment: environment) }
+    let!(:last_deployment) { create(:deployment, environment: environment) }
+
+    it 'is true for last deployment ' do
+      expect(last_deployment.last?).to be(true)
+    end
+
+    it 'is false for previous deployments' do
+      expect(middle_deployment.last?).to be(false)
+      expect(first_deployment.last?).to be(false)
+    end
+  end
+
+  describe '#first?' do
+    let(:environment) { create(:environment) }
+    let!(:first_deployment) { create(:deployment, environment: environment) }
+    let!(:second_deployment) { create(:deployment, environment: environment) }
+    let!(:last_deployment) { create(:deployment, environment: environment) }
+
+    it 'is true for first deployment' do
+      expect(first_deployment.first?).to be(true)
+    end
+
+    it 'is false for subsequent deployments' do
+      expect(second_deployment.first?).to be(false)
+      expect(last_deployment.first?).to be(false)
+    end
+  end
+
   describe '#includes_commit?' do
     let(:project) { create(:project, :repository) }
     let(:environment) { create(:environment, project: project) }

spec/models/environment_spec.rb

@@ -154,6 +154,36 @@ describe Environment do
     end
   end
 
+  describe '#first_deployment' do
+    let(:project)       { create(:project, :repository) }
+    let!(:deployment)   { create(:deployment, environment: environment) }
+    let!(:deployment1)  { create(:deployment, environment: environment) }
+    let(:empty_environment) { create(:environment) }
+
+    it 'returns deployment id for the environment' do
+      expect(environment.first_deployment).to eq(deployment)
+    end
+
+    it 'return nil when no deployment is found' do
+      expect(empty_environment.first_deployment).to eq(nil)
+    end
+  end
+
+  describe '#last_deployment' do
+    let(:project) { create(:project, :repository) }
+    let!(:deployment) { create(:deployment, environment: environment) }
+    let!(:deployment1) { create(:deployment, environment: environment) }
+    let(:empty_environment) { create(:environment) }
+
+    it 'returns deployment id for the environment' do
+      expect(environment.last_deployment).to eq(deployment1)
+    end
+
+    it 'return nil when no deployment is found' do
+      expect(empty_environment.last_deployment).to eq(nil)
+    end
+  end
+
   describe '#environment_type' do
     subject { environment.environment_type }