GlobalID may have an issue with historical objects fetched via as_of

[tagliala]

It is not clear to me what is the correct behavior, but it is worth to mention the following:

Vendor.last.history.last.model_name.name
"Vendor::History"

Vendor.history.last.to_gid
#<GlobalID:0x00007fd3ba2ed9f8 @uri=#<URI::GID gid://app/Vendor::History/123>>

Vendor.as_of(1.day.ago).last.model_name.name
"Vendor"

Vendor.as_of(1.day.ago).last.to_gid
#<GlobalID:0x00007fd3bac4ba18 @uri=#<URI::GID gid://app/Vendor/1>>

[lleirborras]

the 2nd one does not point to historical record

[tagliala]

the 2nd one does not point to historical record

Yes, let me try to clarify

Vendor.last.history.last.model_name.name
"Vendor::History"

Vendor.history.last.to_gid
#<GlobalID:0x00007fd3ba2ed9f8 @uri=#<URI::GID gid://app/Vendor::History/123>>

Vendor.as_of(1.day.ago).last.model_name.name
"Vendor"

Vendor.as_of(1.day.ago).last.to_gid
#<GlobalID:0x00007fd3bac4ba18 @uri=#<URI::GID gid://app/Vendor/1>>

The second one is indeed a class of "Vendor" because it is how chronomodel works.

However, we can't support GlobalID properly because fetching gid://app/Vendor::History/123 will return a "Vendor::History", but Vendor.as_of instantiates a Vendor

[lleirborras]

I understood that, what I mean is that Vendor.as_of(1.day.ago).last.model_name.name should return a History record but I assume in this case that record is "current" and so it returns Vendor

[tagliala]

I understood that, what I mean is that Vendor.as_of(1.day.ago).last.model_name.name should return a History record but I assume in this case that record is "current" and so it returns Vendor

Correct. And it is correct to return a Vendor, so GlobalID should need a custom behavior for this kind of records 😞

I do not know GlobalID internals, so I will take note of this and implement a workaround for our specific use case

[lleirborras]

I do not think it's correct, there should be a convention that when you ask a historical query always get a historical record, even if it's the most recent one, while non-historical queries return normal models

[tagliala]

I do not think it's correct,

I think that Chronomodel itself is not correct, but in the specific case, unfortunately this behavior is correct.

If I'm getting a Vendor.as_of(time), I would like to use that vendor like it is a vendor itself, not its historical reference

Example: if the Vendor is returned as its historical reference with an instance of Vendor::History, a lot of things will fail in a Rails application using chronomodel

• Rails views (= render @vendor): Missing partial vendor/histories/_history
• Policies: Vendor::HistoryPolicy for #<Vendor::History

because everything is expecting an instance of Vendor class

However, here it is a prototype workaround:

GlobalID::Locator.use :chronolocator do |gid|
  collection = gid.model_class
  collection = collection.as_of(Time.parse.utc(gid.params[:as_of])) if gid.params[:as_of] # safe parse here
  collection.find(gid.model_id)
end

Then:

vendor.to_gid(app: 'chronolocator', as_of: vendor.as_of_time&.iso8601) # chronolocator should reflect app name

I don't want to provide a custom locator for chronomodel and override to_gid, but at least we have a working approach for some specific use cases