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Setting an enum attribute to nil fails with “Cannot determine type for nil values” #452
Description
Environment details
- Programming language: Ruby
- OS: Linux but also reproduces on macOS
- Language runtime version: Ruby 3.4.12, Rails/ActiveRecord 8.1.3.1
- Package version: activerecord-spanner-adapter 2.5.0 (the same code is on main), google-cloud-spanner 2.36.0
Steps to reproduce
- Define a model with an enum backed by a nullable STRING(MAX) column:
class Card < ActiveRecord::Base
enum :window_type, {
calendar_day: "calendar_day",
calendar_month: "calendar_month",
}
end
- Create a record with the enum set, then set it to nil:
card = Card.create!(limit_window: "calendar_month")
card.update!(limit_window: nil)
- The update raises Cannot determine type for nil values, and the record isn’t saved. Setting the attribute to a non-nil value works.
Expected: the column is set toNULL.
Thanks!
Activity
amy-found commentedon Nov 6, 2026
In case this is helpful, here's some more info from when I dug into the issue:
Cause
SpannerActiveRecordConverter.convert_active_model_type_to_spanner doesn’t recognize ActiveRecord::Enum::EnumType. That type isn’t in TYPE_MAP and isn’t handled in fallback_convert_active_model_type_to_spanner, so the method returns nil. The bind is then sent without a type, and the client library infers one from the value. That works for a string but not for nil.
Suggested fix
Unwrap the enum to its underlying column type before the lookup, the same way DelegateClass types are unwrapped now: