Add timestamps to broadcasts (#8181)

* Add timestamps to broadcasts

* Update schema version

db/migrate/20200530084533_add_timestamps_to_broadcasts.rb

@@ -0,0 +1,7 @@
+class AddTimestampsToBroadcasts < ActiveRecord::Migration[5.2]
+  def change
+    # NOTE: we need to have nullable timestamps as the table is already
+    # populated. Will remove the NULL clause when data is safely backfilled
+    add_timestamps(:broadcasts, null: true)
+  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: 2020_05_26_151807) do
+ActiveRecord::Schema.define(version: 2020_05_30_084533) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -268,9 +268,11 @@ ActiveRecord::Schema.define(version: 2020_05_26_151807) do
   create_table "broadcasts", id: :serial, force: :cascade do |t|
     t.boolean "active", default: false
     t.text "body_markdown"
+    t.datetime "created_at"
     t.text "processed_html"
     t.string "title"
     t.string "type_of"
+    t.datetime "updated_at"
   end
 
   create_table "buffer_updates", force: :cascade do |t|

lib/data_update_scripts/20200530085153_backfill_broadcasts_timestamps.rb

@@ -0,0 +1,13 @@
+module DataUpdateScripts
+  class BackfillBroadcastsTimestamps
+    def run
+      # Broadcasts didn't have timestamps columns until
+      # 20200530084533_add_timestamps_to_broadcasts was created, thus we can
+      # safely assume that only those with `created_at IS NULL` need their
+      # timestamps overridden
+      Broadcast.where(created_at: nil).order(title: :asc).each do |cast|
+        cast.update(created_at: Time.current, updated_at: Time.current)
+      end
+    end
+  end
+end