The simplest way to group by:

• day
• week
• hour of the day
• and more (complete list below)

🎉 Time zones - including daylight saving time - supported!! the best part

🍰 Get the entire series - the other best part

Supports PostgreSQL, MySQL, MariaDB, and Redshift, plus arrays and hashes (and limited support for SQLite)

💘 Goes hand in hand with Chartkick

Add this line to your application’s Gemfile:

gem "groupdate"

For MySQL, MariaDB, and SQLite, also follow these instructions.

User.group_by_day(:created_at).count
# {
#   Wed, 01 Jan 2025 => 50,
#   Thu, 02 Jan 2025 => 100,
#   Fri, 03 Jan 2025 => 34
# }

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

You can group by:

• second
• minute
• hour
• day
• week
• month
• quarter
• year

and

• minute_of_hour
• hour_of_day
• day_of_week (Sunday = 0, Monday = 1, etc)
• day_of_month
• day_of_year
• month_of_year

Use it anywhere you can use group. Works with count, sum, minimum, maximum, and average. For median and percentile, check out ActiveMedian.

The default time zone is Time.zone. Change this with:

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

or

User.group_by_week(:created_at, time_zone: "Pacific Time (US & Canada)").count
# {
#   Sun, 05 Jan 2025 => 70,
#   Sun, 12 Jan 2025 => 54,
#   Sun, 19 Jan 2025 => 80
# }

Time zone objects also work. To see a list of available time zones in Rails, run rake time:zones:all.

Weeks start on Sunday by default. Change this with:

Groupdate.week_start = :monday

or

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

You can change the hour days start with:

Groupdate.day_start = 2 # 2 am - 2 am

or

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

To get a specific time range, use:

User.group_by_day(:created_at, range: 2.weeks.ago.midnight..Time.now).count

To expand the range to the start and end of the time period, use:

User.group_by_day(:created_at, range: 2.weeks.ago..Time.now, expand_range: true).count

To get the most recent time periods, use:

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

To exclude the current period, use:

User.group_by_week(:created_at, last: 8, current: false).count

You can order in descending order with:

User.group_by_day(:created_at, reverse: true).count

Keys are returned as date or time objects for the start of the period.

To get keys in a different format, use:

User.group_by_month(:created_at, format: "%b %Y").count
# {
#   "Jan 2025" => 10
#   "Feb 2025" => 12
# }

or

User.group_by_hour_of_day(:created_at, format: "%-l %P").count
# {
#    "12 am" => 15,
#    "1 am"  => 11
#    ...
# }

Takes a String, which is passed to strftime, or a Symbol, which is looked up by I18n.localize in i18n scope 'time.formats', or a Proc. You can pass a locale with the locale option.

The entire series is returned by default. To exclude points without data, use:

User.group_by_day(:created_at, series: false).count

Or change the default value with:

User.group_by_day(:created_at, default_value: "missing").count

User.group_by_period(:day, :created_at).count

Limit groupings with the permit option.

User.group_by_period(params[:period], :created_at, permit: ["day", "week"]).count

Raises an ArgumentError for unpermitted periods.

To group by a specific number of minutes or seconds, use:

User.group_by_minute(:created_at, n: 10).count # 10 minutes

If grouping on date columns which don’t need time zone conversion, use:

User.group_by_week(:created_on, time_zone: false).count

If you use Postgres and have a default scope that uses order, you may get a column must appear in the GROUP BY clause error (just like with Active Record’s group method). Remove the order scope with:

User.unscope(:order).group_by_day(:count).count

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 }

Get the entire series with:

users.group_by_day(series: true) { |u| u.created_at }

Count

users.group_by_day { |u| u.created_at }.to_h { |k, v| [k, v.count] }

Time zone support must be installed on the server.

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

You can confirm it worked with:

SELECT CONVERT_TZ(NOW(), ' 00:00', 'Pacific/Honolulu');

It should return the time instead of NULL.

Groupdate has limited support for SQLite.

• No time zone support
• No day_start option
• No group_by_quarter method

If your application’s time zone is set to something other than Etc/UTC (the default), create an initializer with:

Groupdate.time_zone = false

View the changelog

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

• Report bugs
• Fix bugs and submit pull requests
• Write, clarify, or fix documentation
• Suggest or add new features

To get started with development and testing, check out the Contributing Guide.