add fiat balance

app/models/fiat_balance.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: fiat_balances
+#
+#  id              :bigint           not null, primary key
+#  amount_cents    :integer          default(0), not null
+#  amount_currency :string           default("BRL"), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#  user_id         :bigint           not null
+#
+# Indexes
+#
+#  index_fiat_balances_on_user_id  (user_id)
+#
+# Foreign Keys
+#
+#  fk_rails_...  (user_id => users.id)
+#
+class FiatBalance < ApplicationRecord
+  belongs_to :user
+
+  monetize :amount_cents
+
+  validates :amount, presence: true
+end

app/models/user.rb

@@ -26,6 +26,7 @@ class User < ApplicationRecord
 
   has_many :documents, class_name: "UserDocument", dependent: :destroy
   has_many :balances, dependent: :restrict_with_error
+  has_one :fiat_balance, dependent: :restrict_with_error
 
   validates :first_name, :last_name, :email, presence: true
   validates :email, uniqueness: true