<%= form.text_field :check_in_date  %>

ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS.merge!(
  :default => '%m/%d/%Y'
)

<%= f.text_field :some_date, :value => @model_instance.some_date.strftime("%d-%m-%Y") %>

# Default format for displaying dates and times
Date::DATE_FORMATS[:default] = "%m/%d/%Y"
Time::DATE_FORMATS[:default] = "%m/%d/%Y"

MyModel < ActiveRecord::Base
  # ...
  self.columns.each do |column|
    if column.type == :date
      define_method "#{column.name}_before_type_cast" do
        self.send(column.name).to_s
      end
    end
  end
end

def date_mdY(date)
  if date.nil?
    ""
  else
    date.strftime("%m-%d-%Y")
  end
end

<%= f.text_field :some_date, :value => date_mdY(@model_instance.some_date) %>

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

<%= form.text_field :check_in_date, value: model.check_in_date.to_s %>

<%= f.text_field :date3, value: ( l @model.date3 if @model.date3? ) %>

en:
  date:
    formats:
      default: "%d/%m/%Y"

ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS.merge!(
  :default => '%m-%d-%Y' )

def start_date
  super.strftime "%Y/%m/%d %H:%M"
end

<%= f.text_field :start_date, class: 'form-control' %>

after_initialize :init

  private
  def init
    unless time.nil?
      @attributes['time'] = I18n.l(time, format: :short)
    end
  end

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

class EasyDate < ActiveRecord::Type::Date
  def cast_value(value)
    default = super
    parsed = Chronic.parse(value)&.to_date if value.is_a?(String)
    parsed || default
  end
end

class Pony < ApplicationRecord
  attribute :birth_date, EasyDate.new
end

{ column_name: instance_of_a_type_object, ... }

#<ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Money:0x007ff974d62688

date_attributes = attribute_types.select { |_, type| ActiveRecord::Type::Date === type }

date_attributes.each do |attr_name, _type|
  attribute attr_name, EasyDate.new
end

def inherited(klass)
  super
  klass.attribute_types.select { |_, type| ActiveRecord::Type::Date === type }.each do |name, _type|
    klass.attribute name, EasyDate.new
  end
end

module FixDateFormatting
  # the above `inherited` method here
end

# Either this...
class ApplicationRecord < ActiveRecord::Base
  extend FixDateFormatting
end

# ...or this:
ActiveRecord::Base.extend(FixDateFormatting)

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

class EasyDate < ActiveRecord::Type::Date
  def cast_value(value)
    default = super
    parsed = Chronic.parse(value)&.to_date if value.is_a?(String)
    parsed || default
  end
end

module FixDateFormatting
  def inherited(subclass)
    super
    date_attributes = subclass.attribute_types.select { |_, type| ActiveRecord::Type::Date === type }
    date_attributes.each do |name, _type|
      subclass.attribute name, EasyDate.new
    end
  end
end

ActiveRecord::Base.extend(FixDateFormatting)