Deals with MySQL's inability of setting default values for text columns.

coupons.gemspec

@@ -32,6 +32,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'codeclimate-test-reporter'
   spec.add_development_dependency 'pry-meta'
   spec.add_development_dependency 'sqlite3'
+  spec.add_development_dependency 'mysql2', '~> 0.3.13'
   spec.add_development_dependency 'generator_spec'
   spec.add_development_dependency 'database_cleaner'
   spec.add_development_dependency 'globalid'

db/migrate/20150305230400_setup_coupons.rb

@@ -13,7 +13,7 @@ def change
 
       case ActiveRecord::Base.connection.adapter_name
       when 'Mysql2'
-        t.text :attachments, null: false
+        t.text :attachments
       else
         t.text :attachments, null: false, default: '{}'
       end

lib/coupons/models/coupon.rb

@@ -11,6 +11,9 @@ class Coupon < ActiveRecord::Base
       after_initialize do
         self.code ||= Coupons.configuration.generator.call
         self.valid_from ||= Date.current
+
+        attachments_will_change!
+        write_attribute :attachments, {} if attachments.empty?
       end
 
       has_many :redemptions, class_name: 'Coupons::Models::CouponRedemption'

spec/models/coupons/models/coupon_spec.rb

@@ -152,6 +152,18 @@
     expect(coupon.reload).not_to be_redeemable
   end
 
+  it 'sets default attachments object for new records' do
+    coupon = Coupons::Models::Coupon.new
+    expect(coupon.attachments).to eq({})
+  end
+
+  it 'saves default attachments object' do
+    coupon = create_coupon(amount: 10, type: 'amount')
+    coupon.reload
+
+    expect(coupon.attachments).to eq({})
+  end
+
   describe 'serialization' do
     let!(:category) { Category.create!(name: 'Books') }
     let!(:product) { category.products.create!(name: 'All about Rails', price: 29) }

spec/support/active_record.rb

@@ -1,4 +1,7 @@
 system 'rm spec/db/test.sqlite3 &> /dev/null'
+system 'mysqladmin -u root drop coupons_test --force &> /dev/null'
+system 'mysqladmin -u root create coupons_test --default-character-set=utf8'
+system 'dropdb coupons_test &> /dev/null; createdb coupons_test'
 
 ActiveRecord::Migrator.migrations_paths << File.expand_path('../db/migrate', __FILE__)
 ActiveRecord::Migrator.migrations_paths << File.expand_path('../../db/migrate', __FILE__)