CODEWITHSUNDEEP
sqlruby-on-railsrubypostgresqlactiverecord
enjaku
enjaku

Reputation: 346

is it possible to work with the results of ActiveRecord group method directly

I have a model Event, it has an attribute ticket_id. I'm grouping my events by this attribute like this:

Event.group(:ticket_id).having('count(events.ticket_id) > 1')

and it is a perfectly working query, yet I don't understand how to work with the result of such a query directly.

I understand that I, for instance, may call method count on it and get a hash with ticket_ids and number of corresponding events. But I need to get a structure with ticket_ids as keys and arrays of events as values like this one:

{ 1 => [#<Event:1>, #<Event:2>], 2 => [#<Event:3>, #<Event:4>], ... }

I can achieve such a result using plain ruby group_by, but considering the fact that I have several millions of events it seems like not the best solution. Is it possible to achieve the result somehow using ActiveRecord or probably plain SQL?

P.S. I use PostgreSQL

Upvotes: 0

Views: 202

Answers (1)

spickermann
spickermann

Reputation: 106802

ActiveRecord#group creates a SQL GROUP BY clause and that will always return a single list of items and not a nested data structure. Therefore the answer is: No you cannot create such a nested structure just with ActiveRecord

You would need to run something like groub_by(:events_count) on the list returned from ActiveRecord to translate the list into a nested structure.

Upvotes: 1

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