add model and DB constraint for Movement#amount (can't be equal to 0)

Author: markets

app/models/movement.rb

@@ -18,6 +18,8 @@ class Movement < ActiveRecord::Base
           where(created_at: month.beginning_of_month..month.end_of_month)
         }
 
+  validates :amount, numericality: { other_than: 0 }
+
   after_create do
     account.update_balance
   end

db/migrate/20181004200104_add_amount_constraint_to_movements.rb

@@ -0,0 +1,10 @@
+class AddAmountConstraintToMovements < ActiveRecord::Migration
+  def change
+    # Destroy movements (and parent transfer) with amount equal to 0
+    Movement.includes(:transfer).where(amount: 0).find_each do |movement|
+      movement.transfer&.destroy
+    end
+
+    execute 'ALTER TABLE movements ADD CONSTRAINT non_zero_amount CHECK(amount != 0)'
+  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: 20180924164456) do
+ActiveRecord::Schema.define(version: 20181004200104) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"