Add heartbeat model, next_heartbeat_time and update_heartbeat_time on device registration

app/models/device.rb

@@ -2,8 +2,19 @@ class Device < ActiveRecord::Base
   validates :unique_id, :model, presence: true
   validates :unique_id, uniqueness: true
   before_create :generate_access_token
+  after_create :update_last_heartbeats_time
+  has_many :heartbeats, dependent: :destroy
 
   def generate_access_token
     self.access_token = SecureRandom.uuid
   end
+
+  def update_last_heartbeats_time
+    self.last_heartbeat_recd_time = self.updated_at
+    self.save
+  end
+
+  def next_heartbeat_time
+    (self.last_heartbeat_recd_time + HEARTBEAT_INTERVAL).to_i
+  end
 end

app/models/heartbeat.rb

@@ -0,0 +1,14 @@
+class Heartbeat < ActiveRecord::Base
+  belongs_to :device, counter_cache: :heartbeats_count
+
+  after_create :update_device_latest_heartbeat_recd_time
+
+  def update_device_latest_heartbeat_recd_time
+    self.device.last_heartbeat_recd_time = self.created_at
+    self.device.save
+  end
+
+  def next_heartbeat_time
+    device.next_heartbeat_time 
+  end
+end

config/environments/development.rb

@@ -38,4 +38,5 @@ Rails.application.configure do
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+  HEARTBEAT_INTERVAL = 1.hour
 end

config/environments/production.rb

@@ -76,4 +76,5 @@ Rails.application.configure do
 
   # Do not dump schema after migrations.
   config.active_record.dump_schema_after_migration = false
+  HEARTBEAT_INTERVAL = 1.hour
 end

config/environments/test.rb

@@ -39,4 +39,5 @@ Rails.application.configure do
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+  HEARTBEAT_INTERVAL = 1.hour
 end

db/migrate/20151109071857_create_heartbeats.rb

@@ -0,0 +1,9 @@
+class CreateHeartbeats < ActiveRecord::Migration
+  def change
+    create_table :heartbeats do |t|
+      t.references :device, index: true, foreign_key: true
+
+      t.timestamps null: false
+    end
+  end
+end

db/migrate/20151109072450_add_heartbeats_details_to_devices.rb

@@ -0,0 +1,6 @@
+class AddHeartbeatsDetailsToDevices < ActiveRecord::Migration
+  def change
+    add_column :devices, :heartbeats_count, :integer, default: 0
+    add_column :devices, :last_heartbeat_recd_time, :datetime
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20151016122334) do
+ActiveRecord::Schema.define(version: 20151109072450) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -56,6 +56,17 @@ ActiveRecord::Schema.define(version: 20151016122334) do
     t.string   "access_token"
     t.datetime "created_at",                           null: false
     t.datetime "updated_at",                           null: false
+    t.integer  "heartbeats_count",         default: 0
+    t.datetime "last_heartbeat_recd_time"
   end
 
+  create_table "heartbeats", force: :cascade do |t|
+    t.integer  "device_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  add_index "heartbeats", ["device_id"], name: "index_heartbeats_on_device_id", using: :btree
+
+  add_foreign_key "heartbeats", "devices"
 end

spec/factories/heartbeats.rb

@@ -0,0 +1,6 @@
+FactoryGirl.define do
+  factory :heartbeat do
+    association :device
+  end
+
+end

spec/models/device_spec.rb

@@ -1,7 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe Device, type: :model do
-  let(:device) { create(:device) }
+  let!(:device) { create(:device) }
 
   it { should validate_presence_of :unique_id }
   it { should validate_presence_of :model }
@@ -12,4 +12,14 @@ RSpec.describe Device, type: :model do
       expect(device.access_token).not_to be_nil
     end
   end
+
+  describe "heartbeat" do
+    it "last heartbeat time to updated with updated_at time" do
+      expect(Device.last.last_heartbeat_recd_time).not_to be_nil
+    end
+
+    it "next hearbeat time" do
+      expect(Device.last.next_heartbeat_time).not_to be_nil
+    end
+  end
 end

spec/models/heartbeat_spec.rb

@@ -0,0 +1,15 @@
+require 'rails_helper'
+
+RSpec.describe Heartbeat, type: :model do
+  let(:heartbeat){create(:heartbeat)}
+  
+  it "update device  heartbeat details" do
+    device = heartbeat.device
+    expect(device.last_heartbeat_recd_time).to eq(heartbeat.created_at)
+    expect(device.heartbeats_count).to eq(1)
+  end
+
+  it "next heartbeat" do
+    expect(heartbeat.next_heartbeat_time).not_to be_nil
+  end
+end