How to achieve update "batching" in factorybot for traits - ruby

Question

Say you have a Factory in FactoryBot, and say that factory has several traits for associations, and that each trait will need to update the model being created by the factory. So, your main model is MainModel, and you have associations to A, B, C, D, etc...
FactoryBot.define do
factory :main_model
trait :with_a do
after(:create) do |main_model|
# Both sides refer to each other, so this must be done in after(:create).
main_model.update(a_id: create(:a, main_model_id: main_model.id).id)
end
end
trait :with_b do
after(:create) do |main_model|
# Both sides refer to each other, so this must be done in after(:create).
main_model.update(b_id: create(:b, main_model_id: main_model.id).id)
end
end
# More traits omitted...
end
Side note: We're not using ActiveRecord, so we cannot use the associations features built into FactoryBot. Associations must be explicitly registered using a call to update on both sides of the association. Even if I could, I'm not sure it would have any effect?
Now, if client code does the following:
create(:main_model, :with_a, :with_b, :with_c, :with_d)
This is going to result in the following writes to the db:
Create the main record
Create the A record that points to the main.
Update the main record to point to the new A.
Create the B record that points to the main.
Update the main record to point to the new B.
Create the C record that points to the main.
Update the main record to point to the new C.
Create the D record that points to the main.
Update the main record to point to the new D.
Of the above, Numbers 3, 5, 7, and 9 could all be done at the same time, at the very end, if I could simply build up a list of updates that are needed and find a "hook" that would allow me to do one more update after the final trait was applied, and factory bot was ready to return the final result to me. I cannot figure out a way to do that, but the ability to do this would save thousands (probably tens of thousands) of DB writes across my spec suite.
Anyone have any ideas?

Answer 1

You could define a transient variable (I used associations, but call it whatever) - and use this to store all of the associated record IDs for a single record update in an after(:create) block.
Something like this:
FactoryBot.define do
factory :main_model do
transient do
associations { {} }
end
trait :with_a do
associations { super.merge(a_id: create(:a, main_model_id: id).id) }
end
trait :with_a do
associations { super.merge(b_id: create(:b, main_model_id: id).id) }
end
after(:create) do |main_model|
main_model.update(associations)
end
end
end
Usage of the factory remains unchanged - e.g.
create(:main_model, :with_a, :with_b)
...So you shouldn't need to update any of the spec code.