Grouping by week/month/etc & ActiveRecord?

by

In Postgres you can do:

@user.comments.group("DATE_TRUNC('month', created_at)").count

to get:

{"2012-08-01 00:00:00"=>152, "2012-07-01 00:00:00"=>57, "2012-09-01 00:00:00"=>132}

It accepts values from “microseconds” to “millennium” for grouping:
http://www.postgresql.org/docs/8.1/static/functions-datetime.html#FUNCTIONS-DATETIME-TRUNC

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