keep_defaults

Keep Defaults

Prevent ActiveRecord attributes for not null columns with default values from being set to nil.

Why is this necessary? Take this example:

class OrderItem < ApplicationRecord
  # Has column: total numeric(11,2) not null default 0
  # Validation etc...
end

class Order < ApplicationRecord
  # Has columns: total, subtotal, and taxes are all numeric(11,2) not null default 0
  # Validation etc...

  has_many :order_items

  def total
    order_items.sum(&:total) + subtotal + taxes
  end
end

The columns have a default value of 0, but the attributes can still be set to nil. This can make for code that is far from bulletproof:

o = Order.new
o.total  # 0
o.taxes = nil
o.total  # 💥 TypeError: nil can't be coerced into Fixnum

To fix you can do something like:

class OrderItem < ApplicationRecord
  def total
    super || 0
  end
end

class Order < ApplicationRecord
  def total
    order_items.sum(&:total).to_f + subtotal.to_f + taxes.to_f
  end
end

But what about the other contexts in which these can be called or the other attributes you have? This can get tedious.

With Keep Defaults:

class ApplicationRecord < ActiveRecord::Base
  include KeepDefaults
end

o = Order.new
o.total  # 0
o.taxes = nil
o.total  # 0
o.taxes  # 0

Now if an attribute is set to nil it will retain its default value instead.

Installation

Add this line to your application's Gemfile:

gem "keep_defaults"

Or

gem install keep_defaults

Usage

To use everywhere add to ApplicationRecord:

class ApplicationRecord < ActiveRecord::Base
  include KeepDefaults
end

To use for a specific class add it directly to that class:

class Order < ApplicationRecord
  include KeepDefaults
end

License

The gem is available as open source under the terms of the MIT License.