Add this line to your application's Gemfile:

gem 'kalendar'

And then execute:

$ bundle

Or install it yourself as:

$ gem install kalendar

Use the calendar helper.

<%= calendar year: 2015, month: 10 %>

Or, if you want to register some events:

<%= calendar year: 2015, month: 10 do |day| %>
  <% for event in Schedule.find_by_date(day.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 |day| %>
  <% for event in day.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 :property:

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

You can set the HTML's id and class attributes:

<%= calendar id: 'cal', class: 'cal' %>

Use this CSS as your starting point:

.calendar {
  border-collapse: collapse;
  width: 100%;
}

.calendar td,
.calendar th {
  font-family: sans-serif;
  font-size: 14px;
  padding: 20px;
}

.calendar th {
  color: #666;
  text-align: right;
}

.calendar td {
  border: 1px solid #ddd;
  position: relative;
  width: 14.28%;
}

.calendar .not-current-month {
  background: #f5f5f5;
  color: #ccc;
}

.calendar span {
  display: block;
}

.calendar td.events {
  background: #fff;
}

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

.calendar caption {
  text-align: left;
  font-weight: bold;
  font-family: sans-serif;
  font-size: 36px;
}

.calendar .has-events time {
  position: absolute;
  right: 20px;
  top: 20px;
}

.calendar time {
  display: block;
  text-align: right;
}

.calendar td > ul {
  margin: 0;
  padding: 0;
  padding-left: 10px;
  margin-right: 30px;
}

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/fnando/kalendar. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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