Add timezone column to devices table

app/models/device.rb

@@ -2,6 +2,8 @@
 class Device < ActiveRecord::Base
   DEFAULT_MAX_LOGS   = 50
   DEFAULT_MAX_IMAGES = 100
+  TIMEZONES          = ActiveSupport::TimeZone.all.map(&:to_s)
+
   has_many  :users
   has_many  :farm_events,   dependent: :destroy
   has_many  :points,        dependent: :destroy

app/mutations/devices/create.rb

@@ -7,6 +7,7 @@ module Devices
     end
 
     optional do
+      string :timezone, in: Device::TIMEZONES
       string :name
       string :webcam_url
     end
@@ -23,7 +24,7 @@ module Devices
       device
     end
   private
-  
+
     def merge_default_values
       inputs[:name]  ||= random_name
     end

app/mutations/devices/update.rb

@@ -5,6 +5,7 @@ module Devices
     end
 
     optional do
+      string  :timezone, in: Device::TIMEZONES
       string  :name
       string  :webcam_url
     end

db/migrate/20170308231108_add_timezone_to_devices.rb

@@ -0,0 +1,6 @@
+class AddTimezoneToDevices < ActiveRecord::Migration[5.0]
+  def change
+    add_column :devices, :timezone, :string
+    add_index :devices, :timezone
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170213151834) do
+ActiveRecord::Schema.define(version: 20170308231108) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -37,7 +37,9 @@ ActiveRecord::Schema.define(version: 20170213151834) do
     t.string  "webcam_url"
     t.integer "max_log_count",    default: 100
     t.integer "max_images_count", default: 100
+    t.string  "timezone"
     t.index ["planting_area_id"], name: "index_devices_on_planting_area_id", using: :btree
+    t.index ["timezone"], name: "index_devices_on_timezone", using: :btree
   end
 
   create_table "farm_events", force: :cascade do |t|