On Friday, October 5, 2018 at 6:51:21 PM UTC-5, Jeremy Evans wrote:
>
> I've no doubt that what you are describing is happening, but a simple
> example does not reproduce:
>
Alright, I seem to have hit some kind of a nightmarish edge case here. Bear
with me and I'll try to lay it out as clearly as possible. The problem only
occurs under these conditions:
- A (uniqueness?) validation is added to the :order_number field (tested
with both the :constraint_validations and :validation_helpers plugins) on
the model, regardless of the values of :allow_nil and/or :allow_missing and
whether or not there is actually a unique constraint on the column.
- The :defaults_setter plugin is loaded globally or on the model with
:cache=>true.
This combination of plugins and settings causes :order_number to take a nil
value on Model#create and fail the identity column's NOT NULL constraint.
The validation also breaks the Sequel.lit('DEFAULT') workaround, whether
it's specified at Model#create time or as a default value. It gives me the
following error:
/Users/mwp/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sequel-5.13.0/lib/
sequel/adapters/postgres.rb:152:in `async_exec': PG::SyntaxError: ERROR:
DEFAULT is not allowed in this context (Sequel::DatabaseError)
LINE 1: ...t(*) AS "count" FROM "bs" WHERE ("order_number" = DEFAULT) L...
Which makes sense. Let me know if you want the full backtrace.
I can't even begin to image what a fix for this would look like and let me
just state up-front that my expectations of this being fixed are low. In a
perfect world, I would like to add a unique constraint and validation to
this column in my migration (validate { unique :order_number }) and have it
work as expected with the :constraint_validations and :default_setters
plugins with :cache=>true. In the meantime, I have identified the following
alternatives:
- Disable the :default_setters cache on this particular model
- Add a unique constraint but no validation to the :order_number column
(and handle the constraint violation exception in my application framework)
Here's the full repro (which is very close to your original):
DB.create_table(:bs) do
primary_key :id
Integer :order_number, :identity=>true
Integer :n
end
class B < Sequel::Model
plugin :defaults_setter, :cache=>true
plugin :validation_helpers
def validate
super
validates_unique :order_number, :allow_missing=>true
end
end
B.create(:n=>1)
Thanks Jeremy!
P.S. If you don't already know, it is possible to insert duplicate values
for identity columns that are GENERATED BY DEFAULT (vs. GENERATED ALWAYS),
thus the need for a unique constraint and/or validation.
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