Serializes time objects in a lossy fashion leading to failure to look up the record from the DB

[erikbelusic]

When passing a model instance with a CPK and a timestamp as part of the CPK into ActiveJobs an error is raised that the record cannot be found during deserialization. I tracked this down to lossy encoding of timestamps. Using to_s on the timestamp drops milli/micro/nano second precision which is often stored in the DB, which causes a failure to find the record.

➜ irb
3.3.5 :001 > require "active_support/all"
 => true
3.3.5 :002 > t1 = Time.current
 => 2024-12-12 22:48:28.030654 -0500
3.3.5 :003 > t2 = Time.parse(t1.to_s)
 => 2024-12-12 22:48:28 -0500
3.3.5 :004 > t1 == t2
 => false

I'd suggest converting time objects to a string with .iso8601(9) as that seems to be the highest precision we will encounter on timestamps. I am happy implement this fix if someone can provide guidance on a preference between checking the class type of the id part or checking if it responds to iso8601. Also if there is a preferred testing strategy for something like this.

Extra context on the use case. I have records in TimescaleDB hypertables that often have primary keys of [:created_at, :key].