Rails ignores the default date format after upgrading from 6.1 to 7.0

Question

Our application previously defined the default date format as DD/MM/YYYY in config/application.rb like so:

Date::DATE_FORMATS[:default] = '%d/%m/%Y'

This worked as expected in Rails 6.1, but after upgrading to Rails 7.0 it now appears to be ignored by .to_s:

Loading development environment (Rails 7.0.2.2)
3.0.1 :001 > Date::DATE_FORMATS[:default]
 => "%d/%m/%Y" 
3.0.1 :002 > Date.new(2022, 12, 31).to_s
 => "2022-12-31"
3.0.1 :003 > Date.new(2022, 12, 31).to_fs
 => "31/12/2022" 

How can I have .to_s implement this behaviour in Rails 7.0+?

Answer 1

Bear in mind, config.active_support.disable_to_s_conversion doesn't restore the original functionality of to_s on a date. Your dates will not hit the default formatter you have configured.

I'm not sure if any of this is intentional.

You have two options to fix this:

1. Find everywhere you need your date to display in your selected format and add .to_fs. This is probably the more correct way to fix this.
2. Or do what we did and defy the wishes of the rails devs. Add an initializer that overrides the .to_s method on a date because going to over 9000 different locations to add .to_fs to each date display in your code is just too much for you to think about right now.

./config/initializers/date_format_fix.rb

require "date"

class Date
  def to_s(format = :default)
    if formatter = DATE_FORMATS[format]
      if formatter.respond_to?(:call)
        formatter.call(self).to_s
      else
        strftime(formatter)
      end
    else
      to_default_s
    end
  end
end

The same can be done with Time and DateTime.