Group records by both month and year in Rails

Question

I\'m on Ruby 1.9.2, Rails 3.0.x and I use MySQL DB. I have a Messages Model, where one can post new messages every day.

I have an index action where I want to display t

Answer 1

In SQL:

select * from messages group by year(created_at), month(created_at);

In Rails:

Message.all.group_by { |m| m.created_at.beginning_of_month }

Answer 2

Use Group Date.

It supports time zones, so if you ever need to - the code will easily evolve.

https://github.com/ankane/groupdate

Answer 3

ModelName.all.group_by { |m| m.created_at.month }

This will work, however month will be returned as the index. Ex. Nov would refer to 11

Answer 4

Message.select("date_trunc('month', created_at) as month").group("month")

Answer 5

To group by year and by month (e.g. not having december 2020 with december 2021):

Message.group("date_trunc('year', created_at), date_trunc('month', created_at)")

Tested on PostgreSQL