Miti

Converts between English (AD) and Nepali (BS) dates. Includes a CLI app, Rails helpers (date picker, calendar, model concern), and full Rails integration.

Installation

$ gem install miti

Or add to your Gemfile:

$ bundle add miti

CLI

All date arguments must be in YYYY-MM-DD or YYYY/MM/DD format.

$ miti today
# [2082-01-15 BS] Baisakh 15, 2082 Monday
# [2025-04-28 AD] April 28, 2025 Monday

$ miti to_bs 2025-04-28
# [2082-01-15 BS] Baisakh 15, 2082 Monday

$ miti to_ad 2082-01-15
# [2025-04-28 AD] April 28, 2025 Monday

$ miti next
# 17 days left until 1st Jestha
# Current month's last date => 31 Baisakh

Ruby API

require "miti"

Miti.to_bs("2025-04-28")
#=> #<Miti::NepaliDate:0x... @barsa=2082, @mahina=1, @gatey=15>

Miti.to_bs("2025-04-28").descriptive
#=> "Baisakh 15, 2082 Monday"

Miti.to_bs("2025-04-28").descriptive(nepali: true)
#=> "बैशाख 15, 2082 Monday(सोमबार)"

Miti.to_bs("2025-04-28").to_s
#=> "2082-01-15"

Miti.to_bs("2025-04-28").format("%g %b %m")
#=> "15 2082 01"

Miti.to_bs("2025-04-28").format("%B %g, %Y %A")
#=> "Baishakh 15, 2082 Monday"

Miti.to_bs("2025-04-28").format("%B %g, %Y %A", nepali: true)
#=> "वैशाख 15, 2082 सोमबार"

Miti.to_ad("2082-01-15")
#=> #<Date: 2025-04-28 ...>

format tokens. The named form (e.g. %<gatey>g) works too.

Token	Output
%g	Day, zero-padded (05)
%m	Month, zero-padded (01)
%b / %Y	Year (2082)
%B	Month name
%A	Weekday name

With nepali: true, %B and %A come out in Nepali.

Rails Integration

Setup

$ rails generate miti:install

The generator:

• adds import "miti" to app/javascript/application.js. Importmap apps get the pins from the gem automatically
• adds stylesheet_link_tag "miti/calendar" to your application layout
• copies the JS files into app/javascript/miti/ when it detects a bundler (esbuild, webpack, rollup or vite)

Options:

$ rails generate miti:install --copy-styles      # copy calendar.css into your app for customization
$ rails generate miti:install --copy-javascript  # force-copy the JS files into app/javascript/miti/

To undo: rails destroy miti:install

To set things up by hand, use miti_assets in your layout's <head>. It includes the calendar data and the stylesheet:

<%= miti_assets %>

Upgrading from 1.2.x

• nepali_date_field now submits the BS string (e.g. event[happened_on] = "2082-01-15") instead of a hidden AD input. has_nepali_date converts it to AD on assignment. Without the model concern, convert it in the controller (see Controller concern)
• The calendar data endpoint is now POST. Re-run rails generate miti:install --copy-javascript if you copied the JS files earlier

Date picker (popover calendar)

<%= form.nepali_date_field :happened_on %>
<!-- readonly text input with calendar icon that opens a month/year picker popover -->
<!-- submits as event[happened_on] — no _bs suffix needed -->

With a default value:

<%= form.nepali_date_field :happened_on, value: "2082-01-15" %>

Themes

<%= form.nepali_date_field :happened_on, theme: :dark %>
<%= form.nepali_date_field :happened_on, theme: :tokyo_night %>

Available themes: light (default), dark, indigo, midnight, tokyo_night, nord.

Use data-miti-theme on any ancestor to style a group of pickers:

<div data-miti-theme="dark">
  <%= form.nepali_date_field :start_date %>
  <%= form.nepali_date_field :end_date %>
</div>

Dark mode auto-detects prefers-color-scheme: dark. Set data-miti-theme-auto="false" on any ancestor to disable:

<div data-miti-theme-auto="false">
  <%= form.nepali_date_field :happened_on %>
</div>

Date range picker

<%= form.nepali_date_range_field :start_date, :end_date %>
<!-- Single clickable input + two hidden inputs; drag-to-select or click-to-select range -->

With defaults:

<%= form.nepali_date_range_field :start_date, :end_date,
      start_value: "2082-01-15", end_value: "2082-02-10" %>

Without a form builder:

<%= nepali_date_range_field :event, :start_date, :end_date %>

The display shows a friendly range like "Baisakh 15 – Jestha 3, 2082". Opens a single popover with drag-to-select. Fires miti:range-selected custom event on selection.

Options: theme, start_value, end_value, trigger_html.

Date select (3 dropdowns)

<%= form.nepali_date_select :happened_on %>
<!-- renders year, month, day select elements -->

Model concern

class Event < ApplicationRecord
  include Miti::Rails::ModelConcern
  has_nepali_date :happened_on
end

This defines:

• event.happened_on_bs — returns BS date as Miti::NepaliDate
• event.happened_on_bs = "2082-01-15" — sets the AD column from a BS string
• event.happened_on_bs_human — readable description (respects I18n.locale)
• event.happened_on = "2083-01-15" — auto-converts BS string to AD via custom type

Optional BS column storage

class Event < ApplicationRecord
  include Miti::Rails::ModelConcern
  has_nepali_date :happened_on, store_bs: true
end

The setter writes the BS string to the happened_on_bs column on assignment. Generate the migration:

$ rails generate miti:store_bs Event happened_on

With store_bs: true:

• event.happened_on_bs reads from the DB column directly (zero conversion cost)
• Falls back to converting from AD if the column is empty
• The setter writes the BS string to the column immediately
• If only the BS column is set, it is synced to the AD column in before_validation

Controller concern

Converts BS date params to AD Date objects before an action runs. Use it for params that don't go through has_nepali_date, such as filters:

class EventsController < ApplicationController
  include Miti::Rails::ControllerConcern
  auto_convert_bs_dates :from, :to, only: :index   # params[:from], params[:to] become AD Dates; invalid values are left as-is

  def index
    date = parse_date_param(params[:date])  # BS string -> AD Date, Date.current if blank or invalid
  end
end

Calendar grid

<%= nepali_calendar(year: 2082, month: 1) do |day| %>
  <%= day.gatey %>
<% end %>

Renders a monthly grid with Turbo Frame navigation.

Agenda view

<%= nepali_calendar_agenda(start_date, end_date, group_by: :week) do |day| %>
  <%= day.descriptive %>
<% end %>

Renders a grouped list of dates.

DayPresenter

Yielded to calendar/agenda blocks:

Method	Returns
day.gatey	Day of month (1-32)
day.barsa	Year
day.mahina	Month (1-12)
day.bar	Weekday index (0=Sunday)
day.tarik	Equivalent AD Date
day.to_s	BS date as yyyy-mm-dd
day.descriptive	Human readable
day.today? / day.sunday? / day.saturday?	Boolean checks

Ruby version

Supports Ruby 3.1 through 4.x. Rails integration loads automatically when Rails is defined.

Development

$ bin/setup
$ bundle exec rake spec
$ bin/console

Contributing

Bug reports and pull requests are welcome at github.com/xkshitizx/miti.

License

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