How do I group by day instead of date?

Question

ok so i have

 >> list = Request.find_all_by_artist(\"someBand\")
=> [#

        

Answer 1

you can use GROUP BY DATE(created_at) in MySQL

On ruby code you can use like this

list.group('DATE(created_at)').map {|k,v| [k, v.length]}.sort

Answer 2

There is a gem for that: groupdate.

Usage (from the docs):

User.group_by_day(:created_at).count
# {
#   2013-04-16 00:00:00 UTC => 50,
#   2013-04-17 00:00:00 UTC => 100,
#   2013-04-18 00:00:00 UTC => 34
# }

Answer 3

Group without extra gems:

def self.group_by_day items
   data = items.group_by{|x| x.created_at.to_date}
   chart_data = {}

   data.each do |a,b|
     chart_data.merge!({a => b.count})
   end

   return chart_data
end

Answer 4

Ipsum's answer is actually good and probably the best:

In Arel:

requests = Arel::Table.new(:requests)
query = requests.project("COUNT(*), CAST(requests.created_at AS DATE) as created_at")
query = query.group("CAST (requests.created_at AS DATE)")
Request.find_by_sql(query.to_sql)

Answer 5

I think this is a much more elegant and simple solution

list.group_by{|x| x.created_at.strftime("%Y-%m-%d")} 

Answer 6

Time is a quite complex object to group by. Assuming you want to group by the creation date, instead of the full Time, start creating a custom method in your model to return the group criteria.

The method should return the creation date, possibly as string.

def group_by_criteria
  created_at.to_date.to_s(:db)
end

Then, group by that method.

list.group_by(&:group_by_criteria).map {|k,v| [k, v.length]}.sort