Introduce custom timezone configuration support for ActiveRecord enumerators

[yigitozkavci]

Background

Current implementation of column_value is prone to faulty serialisation if ActiveRecord's timezone differs from the timezone in the database.

In our case, we are using Eastern Time (US & Canada) in our Rails application but our database stores datas in UTC.

Following console log demonstrates the issue:

[2] pry(#<>)> Time.use_zone("UTC"){ OrderTransaction.select(:created_at).order(created_at: :desc).take(1).first.created_at.strftime("%Y-%m-%d %H:%M:%S.%N") }
D, [2024-10-09T16:54:28.648833 #17479] DEBUG -- :   CACHE OrderTransaction Load (0.2ms)  SELECT `order_transactions`.`created_at` FROM `order_transactions` ORDER BY `order_transactions`.`created_at` DESC LIMIT 1
D, [2024-10-09T16:54:28.649738 #17479] DEBUG -- :   ↳ (pry):2:in `block in build_enumerator'
=> "2024-10-09 08:02:49.000000000"
[3] pry(#<>)> OrderTransaction.select(:created_at).order(created_at: :desc).take(1).first.created_at.strftime("%Y-%m-%d %H:%M:%S.%N")
D, [2024-10-09T16:54:37.011976 #17479] DEBUG -- :   CACHE OrderTransaction Load (0.3ms)  SELECT `order_transactions`.`created_at` FROM `order_transactions` ORDER BY `order_transactions`.`created_at` DESC LIMIT 1
D, [2024-10-09T16:54:37.012498 #17479] DEBUG -- :   ↳ (pry):3:in `build_enumerator'
=> "2024-10-09 04:02:49.000000000"

Fix

Current implementation of column_value assumes that the database & the application are using the same timezone regardless of it being UTC or not. However, it is generally accepted that database column values that are of type date are assumed to be UTC unless explicitly stated otherwise. Therefore, any serialisation may assume as such instead of assuming them both having the same timezone.

To make this change not potentially a breaking change we've made it configurable with a default value of nil. This will allow users of this library to configure a custom timezone if need be.

[Mangara]

Just missing a change to enumerator_builder to pass through the timezone, LGTM otherwise.

[Mangara]

Just missing a change to enumerator_builder to pass through the timezone

Never mind, the splats take care of this. Good to merge!

[bdewater]

Not sure if this has to be configured explicitly. Active Job serializes and deserializes the timezone on the job, and sets it in an around_perform hook. Could this simply be:

value.in_time_zone(::Time.zone)

[Mangara]

Isn't that the default behaviour? I think the original issue is with a job enqueued (and running) in the local timezone, but reading data that was stored in a different time zone (UTC).