feat: Add APIs for Campaigns (#2175)

app/models/campaign.rb

@@ -0,0 +1,49 @@
+# == Schema Information
+#
+# Table name: campaigns
+#
+#  id            :bigint           not null, primary key
+#  content       :text             not null
+#  description   :text
+#  enabled       :boolean          default(TRUE)
+#  title         :string           not null
+#  trigger_rules :jsonb
+#  created_at    :datetime         not null
+#  updated_at    :datetime         not null
+#  account_id    :bigint           not null
+#  display_id    :integer          not null
+#  inbox_id      :bigint           not null
+#  sender_id     :integer
+#
+# Indexes
+#
+#  index_campaigns_on_account_id  (account_id)
+#  index_campaigns_on_inbox_id    (inbox_id)
+#
+# Foreign Keys
+#
+#  fk_rails_...  (account_id => accounts.id)
+#  fk_rails_...  (inbox_id => inboxes.id)
+#
+class Campaign < ApplicationRecord
+  validates :account_id, presence: true
+  validates :inbox_id, presence: true
+  belongs_to :account
+  belongs_to :inbox
+  belongs_to :sender, class_name: 'User', optional: true
+
+  has_many :conversations, dependent: :nullify, autosave: true
+
+  after_commit :set_display_id, unless: :display_id?
+
+  private
+
+  def set_display_id
+    reload
+  end
+
+  # creating db triggers
+  trigger.before(:insert).for_each(:row) do
+    "NEW.display_id := nextval('camp_dpid_seq_' || NEW.account_id);"
+  end
+end