Rails - Date Query using group by and count - sql

Question

I'm trying to get the number of calls by commercial week. I've written the sql:
select strftime('%W', date_time_origination) as week, count(*)
from calls
group by week;
I then tried to run this in rails, firstly using this:
calls_by_week = Call.select("strftime('%W',date_time_origination) as week, count(*) as total_number_of_calls").group("week")
This returned a collection of objects with the correct data but repeated multiple times (json representation):
[{ "total_number_of_calls": 5435, "week": 39 },.....]
Given that it should have returned one object, I tried changing the rails query structure:
calls_by_week = Call.select("strftime('%W', date_time_origination) as week").group("strftime('%W', date_time_origination)").count
This time, the query returned one hash, minus the named params:
{ "31": 3123, "32": 1231,... }
I'd like to have the data, in json, presented as follows:
{ "week": 31, "total_number_of_calls": 12412,.....}
Is there a way of eliminating the duplication produced by the first query?

Answer 1

First: if you use Call.select(...) rails will try to instanciate Call objects. What you want are not Call objects, just hashes. You can use Call.connection.execute("SELECT .... blah blah").to_enum.to_a and use the resulting array of arrays.
But to convert your result to hash form, use
returned_hash = { "31": 3123, "32": 1231,... }
what_you_want = returned_hash.collect do |k,v|
{"week" => k.to_i, "total_number_of_calls" => v.to_i}
end
Another way is to use .uniq applied to the query, it will still build Call objects, but at least they will not have repeated data.