fix(coupon): Coupon code column missing NOT NULL constraint in database

app/graphql/types/coupons/create_input.rb

@@ -7,7 +7,7 @@ class CreateInput < Types::BaseInputObject
 
       argument :amount_cents, GraphQL::Types::BigInt, required: false
       argument :amount_currency, Types::CurrencyEnum, required: false
-      argument :code, String, required: false
+      argument :code, String, required: true
       argument :coupon_type, Types::Coupons::CouponTypeEnum, required: true
       argument :description, String, required: false
       argument :frequency, Types::Coupons::FrequencyEnum, required: true

app/graphql/types/coupons/object.rb

@@ -10,7 +10,7 @@ class Object < Types::BaseObject
 
       field :amount_cents, GraphQL::Types::BigInt, null: true
       field :amount_currency, Types::CurrencyEnum, null: true
-      field :code, String, null: true
+      field :code, String, null: false
       field :coupon_type, Types::Coupons::CouponTypeEnum, null: false
       field :description, String, null: true
       field :frequency, Types::Coupons::FrequencyEnum, null: false

app/graphql/types/coupons/update_input.rb

@@ -5,6 +5,7 @@ module Coupons
     class UpdateInput < Types::Coupons::CreateInput
       graphql_name "UpdateCouponInput"
 
+      argument :code, String, required: false
       argument :id, String, required: true
     end
   end

app/models/coupon.rb

@@ -49,7 +49,7 @@ class Coupon < ApplicationRecord
   monetize :amount_cents, disable_validation: true, allow_nil: true
 
   validates :name, presence: true
-  validates :code, uniqueness: {conditions: -> { where(deleted_at: nil) }, scope: :organization_id}
+  validates :code, presence: true, uniqueness: {conditions: -> { where(deleted_at: nil) }, scope: :organization_id}
 
   validates :amount_cents, presence: true, if: :fixed_amount?
   validates :amount_cents, numericality: {greater_than: 0}, allow_nil: true
@@ -101,7 +101,7 @@ def parent_and_overriden_plans
 #  id                       :uuid             not null, primary key
 #  amount_cents             :bigint
 #  amount_currency          :string
-#  code                     :string
+#  code                     :string           not null
 #  coupon_type              :integer          default("fixed_amount"), not null
 #  deleted_at               :datetime
 #  description              :text

db/migrate/20260512155310_backfill_coupon_codes.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class BackfillCouponCodes < ActiveRecord::Migration[8.0]
+  disable_ddl_transaction!
+
+  def up
+    Coupon.unscoped.where(code: nil).find_in_batches(batch_size: 1000) do |batch|
+      Coupon.unscoped.where(id: batch.pluck(:id))
+        .update_all("code = 'coupon-' || id::text") # rubocop:disable Rails/SkipsModelValidations
+    end
+  end
+
+  def down
+    # irreversible
+  end
+end

db/migrate/20260513105209_add_code_not_null_check_constraint_to_coupons.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddCodeNotNullCheckConstraintToCoupons < ActiveRecord::Migration[8.0]
+  def change
+    add_check_constraint :coupons, "code IS NOT NULL",
+      name: "coupons_code_not_null", validate: false, if_not_exists: true
+  end
+end

db/migrate/20260513105210_validate_coupons_code_not_null.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class ValidateCouponsCodeNotNull < ActiveRecord::Migration[8.0]
+  disable_ddl_transaction!
+
+  def up
+    validate_check_constraint :coupons, name: "coupons_code_not_null"
+    change_column_null :coupons, :code, false
+    remove_check_constraint :coupons, name: "coupons_code_not_null"
+  end
+
+  def down
+    add_check_constraint :coupons, "code IS NOT NULL", name: "coupons_code_not_null", validate: false
+    change_column_null :coupons, :code, true
+  end
+end

db/structure.sql

@@ -2109,7 +2109,7 @@ CREATE TABLE public.coupons (
     id uuid DEFAULT gen_random_uuid() NOT NULL,
     organization_id uuid NOT NULL,
     name character varying NOT NULL,
-    code character varying,
+    code character varying NOT NULL,
     status integer DEFAULT 0 NOT NULL,
     terminated_at timestamp(6) without time zone,
     amount_cents bigint,
@@ -12216,6 +12216,9 @@ SET search_path TO "$user", public;
 
 INSERT INTO "schema_migrations" (version) VALUES
 ('20260517101105'),
+('20260513105210'),
+('20260513105209'),
+('20260512155310'),
 ('20260512142543'),
 ('20260504134804'),
 ('20260430102814'),
@@ -13214,4 +13217,3 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20220530091046'),
 ('20220526101535'),
 ('20220525122759');
-

spec/graphql/types/coupons/object_spec.rb

@@ -10,7 +10,7 @@
     expect(subject).to have_field(:organization).of_type("Organization")
     expect(subject).to have_field(:amount_cents).of_type("BigInt")
     expect(subject).to have_field(:amount_currency).of_type("CurrencyEnum")
-    expect(subject).to have_field(:code).of_type("String")
+    expect(subject).to have_field(:code).of_type("String!")
     expect(subject).to have_field(:coupon_type).of_type("CouponTypeEnum!")
     expect(subject).to have_field(:description).of_type("String")
     expect(subject).to have_field(:frequency).of_type("CouponFrequency!")

spec/models/coupon_spec.rb

@@ -21,6 +21,7 @@
 
   describe "validations" do
     it { is_expected.to validate_presence_of(:name) }
+    it { is_expected.to validate_presence_of(:code) }
     it { is_expected.to validate_exclusion_of(:reusable).in_array([nil]) }
 
     describe "of amount cents" do