Created: 2008-09-16 14:39
Updated: 2019-02-12 06:16
License: mit



has_calendar is a view helper that creates a calendar using a table. You can easily add events with any content.

This plugin relies on the cal command, available on *nix systems. Instead of calculating dates, I parse the output.

NOTE: Only on Mac OS X (Unix?) the first day of week is Sunday; Linux (tested on Ubuntu) uses the argument -m, starting on Monday.

Want this to work on Windows systems? Make sure you have a command cal on your PATH that returns exactly the *nix output (haven't tested though).


  1. Install the plugin with script/plugin install git://github.com/fnando/has_calendar.git


<%= calendar :year => 2008, :month => 9 %>

or, if you want to register some events:

<% calendar :year => 2008, :month => 9 do |date| %>
	<% for event in Schedule.find_by_date(date) %>
		<%= link_to event.title, event_path(event) %>
	<% end %>
<% end %>

As you can see, this will hit your database up to 31 times (one hit for each day) if you don't optimize it. Fortunately, you can use the options :events:

<% calendar :events => Schedule.all do |date, events| %>
	<% for event in events %>
		<%= link_to event.title, event_path(event) %>
	<% end %>
<% end %>

By default, each record will use the created_at attribute as date grouping. You can specify a different attribute with the option :field:

<% calendar :events => Schedule.all, :field => :scheduled_at do |date, events| %>
	<!-- do something -->
<% end %>

By default, has_calendar will look for a date format called :day\_of\_week to use on the header of the calendar, you can change it using the :header_format option:

    <%= calendar :header_format => :short_day_name %>

You can also change the caption provided by has_calendar (that defaults to the :default format):

    <%= calendar :header_format => :short_day_name, :caption_format => :month_year %>

To set formats do something like this:

Date::DATE_FORMATS[:short_day_name] = '%a' # => (Sun..Sat)

Or on your locale file, if your application is internationalized.

You can set the HTML id: <%= calendar :id => 'cal' %>

Formatting the calendar

You can use this CSS to start:

#calendar {
	border-collapse: collapse;
	width: 100%;

#calendar td,
#calendar th {
	color: #ccc;
	font-family: "Lucida Grande",arial,helvetica,sans-serif;
	font-size: 10px;
	padding: 6px;

#calendar th {
	border: 1px solid #ccc;
	background: #ccc;
	color: #666;
	text-align: left;

#calendar td {
	background: #f0f0f0;
	border: 1px solid #ddd;

#calendar span {
	display: block;

#calendar td.events {
	background: #fff;

#calendar td.today {
	background: #ffc;
	color: #666;

#calendar caption {
  display: none;


  • Write some specs as soon as possible!


Copyright (c) 2008 Nando Vieira, released under the MIT license

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