View the Project on GitHub ankane/groupdate


The simplest way to group by:

:tada: Time zones supported!! the best part

:cake: Get the entire series - the other best part

Works with Rails 3.1+

Supports PostgreSQL and MySQL, plus Arrays and Hashes

Build Status

:cupid: Goes hand in hand with Chartkick

Get Started

Group by day

# {
#   2013-04-16 00:00:00 UTC => 50,
#   2013-04-17 00:00:00 UTC => 100,
#   2013-04-18 00:00:00 UTC => 34
# }

Results are returned in ascending order by default, so no need to sort.

You can also group by:


Use it anywhere you can use group.

Time Zones

The default time zone is Change this with:

Groupdate.time_zone = "Pacific Time (US & Canada)"


User.group_by_week(:created_at, time_zone: "Pacific Time (US & Canada)").count
# {
#   2013-03-10 00:00:00 PST => 70,
#   2013-03-17 00:00:00 PDT => 54,
#   2013-03-24 00:00:00 PDT => 80
# }

Time zone objects also work.

Week Start

Weeks start on Sunday by default. Change this with:

Groupdate.week_start = :mon # first three letters of day


User.group_by_week(:created_at, week_start: :mon).count

Day Start

You can change the hour days start with:

Groupdate.day_start = 2 # 2 am - 2 am


User.group_by_day(:created_at, day_start: 2).count

Time Range

To get a specific time range, use:

User.group_by_day(:created_at, range:

To get the most recent time periods, use:

User.group_by_week(:created_at, last: 8).count # last 8 weeks


You can order in descending order with:



User.group_by_day(:created_at).order("day desc").count

Pretty Keys

To get keys in a different format, use:

User.group_by_hour_of_day(:created_at, format: "%l %P").count.keys.first # 12 am

Takes a String, which is passed to strftime, or a Proc

Arrays and Hashes

users.group_by_day{|u| u.created_at } # or group_by_day(&:created_at)

Supports the same options as above

users.group_by_day(time_zone: time_zone){|u| u.created_at }


Add this line to your application’s Gemfile:

gem 'groupdate'


Time zone support must be installed on the server.

mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

For JRuby

Use the master version of your JDBC adapter. You will get incorrect results for versions before this commit.

# postgresql
gem "activerecord-jdbcpostgresql-adapter", :github => "jruby/activerecord-jdbc-adapter"

# mysql
gem "activerecord-jdbcmysql-adapter", :github => "jruby/activerecord-jdbc-adapter"

Upgrading to 2.0

Groupdate 2.0 brings a number a great improvements. Here are two things to be aware of:


View the changelog

Groupdate follows Semantic Versioning


Everyone is encouraged to help improve this project. Here are a few ways you can help: